Merge pull request 'Let the harness declare what it runs on the host' (#141) from harness-host-exec into harness-guard-registration

Reviewed-on: #141
Reviewed-by: branderson <brad@branderson.io>

README.md

@@ -339,7 +339,7 @@ dejima ~/repos/some-project
 
 By default the container's entry point is bare `claude` (always running with
 `--dangerously-skip-permissions`, regardless of how it's invoked; see
-`docker/claude-wrapper.sh`), so a fresh clone of this repo works with no
+`docker/harness-wrapper.sh`), so a fresh clone of this repo works with no
 editor setup at all.
 
 The loop, in the part every workflow shares: point it at a project, ask for a

bin/dejima

@@ -25,6 +25,8 @@ source "$SCRIPT_DIR/dejima-provider-lib.sh"
 source "$SCRIPT_DIR/dejima-color-lib.sh"
 # shellcheck source=dejima-slug-lib.sh
 source "$SCRIPT_DIR/dejima-slug-lib.sh"
+# shellcheck source=dejima-harness-lib.sh
+source "$SCRIPT_DIR/dejima-harness-lib.sh"
 # fd 2: everything this script says for itself goes to stderr, so the
 # session's own stdout stays exactly what the container wrote.
 color_init 2
@@ -310,6 +312,13 @@ if [ -z "$DEJIMA_HARNESS_NAME" ]; then
 fi
 provider_validate_selection "$DEJIMA_FORGE_NAME" "$DEJIMA_WORKFLOW_NAME" "$DEJIMA_HARNESS_NAME" || exit 1
 
+# The selected harness's plugin: what dejima does for this harness that no
+# manifest value could state. Loaded once the selection is validated, and
+# before anything that calls a hook. A manifest without a plugin is refused
+# rather than treated as a lighter kind of support - see "Adding a new
+# harness" in docs/development.md.
+harness_plugin_load "$DEJIMA_HARNESS_NAME"
+
 # Whether GitHub is a push destination this session, which the briefing tells
 # the agent about. Two ways in: the per-launch flag, or a forge whose hosts
 # core allowlists (github) under a workflow that pushes. Derived from the
@@ -747,7 +756,6 @@ SANDBOX_AUDIT_STATE="$(mktemp "${TMPDIR:-/tmp}/dejima-audit.XXXXXX")"
 # and SANDBOX_DERIVED_CONTEXT is one of the `rm -rf` arguments.
 DEJIMA_NOTIFY_DIR=""
 DEJIMA_SESSION_FILE=""
-SANDBOX_REMOTE_SETTINGS_TMP=""
 SANDBOX_NVIM_LOCKFILE=""
 SANDBOX_DERIVED_DOCKERFILE=""
 SANDBOX_DERIVED_CONTEXT=""
@@ -805,7 +813,7 @@ cleanup() {
     fi
     rm -f "$SANDBOX_SETTINGS_FILE" "$SANDBOX_CLAUDE_JSON_FILE" "${SANDBOX_NVIM_LOCKFILE:-}" "${SANDBOX_FAKE_CREDENTIALS_FILE:-}" "${SANDBOX_DERIVED_DOCKERFILE:-}" "${SANDBOX_BRIEFING_FILE:-}" || true
     rm -rf "${SANDBOX_GITCONFIG_DIR:-}" "${SANDBOX_ANTHROPIC_PROXY_DIR:-}" "${SANDBOX_DERIVED_CONTEXT:-}" || true
-    rm -f "${DEJIMA_SESSION_FILE:-}" "${SANDBOX_REMOTE_SETTINGS_TMP:-}" || true
+    rm -f "${DEJIMA_SESSION_FILE:-}" || true
     # Unlike the silent `|| true` guards above, this removal (and, before
     # the audit below was moved in, the last command of an EXIT trap) warns
     # out loud when it fails: the marker directory is bind-mounted
@@ -912,6 +920,42 @@ case "$SANDBOX_CMD" in
         ;;
 esac
 export SANDBOX_CMD
+
+# What the wrapper inside the container needs to shadow the harness's binary
+# and pin its flags, resolved here because the manifests are host-side data
+# the container never sees. Every value is the selected harness's own; none
+# of it is written down in the image.
+#
+# SANDBOX_HARNESS_COMMAND is the name to shadow, and is the manifest's rather
+# than [core] command: overriding the latter to `nvim` changes what dejima
+# launches, not which harness is wrapped, and an editor-driven session that
+# then runs the harness from a terminal must still get the flags.
+SANDBOX_HARNESS_COMMAND="$(manifest_get harness "$DEJIMA_HARNESS_NAME" command)"
+SANDBOX_HARNESS_REAL="$(manifest_get harness "$DEJIMA_HARNESS_NAME" command_path)"
+SANDBOX_HARNESS_ARGS="$(manifest_get harness "$DEJIMA_HARNESS_NAME" no_confirm_args)"
+# Named in full rather than templated: the settings layer's container-side
+# path is dejima's own fixed contract (docker-compose.yml mounts it there),
+# not a value that varies per run, and {{...}} in a manifest belongs to the
+# briefing composer's substitution rather than to a second mechanism that
+# merely looks like it.
+SANDBOX_HARNESS_SETTINGS="$(manifest_get harness "$DEJIMA_HARNESS_NAME" settings_args)"
+# Unattended operation is R1 of the capability bar, and a harness whose
+# manifest names no way to ask for it would run asking for confirmation on
+# every tool call, against a container built on the premise that it does not.
+# That fails silently and looks like the harness hanging, so refuse instead.
+if [ -z "$SANDBOX_HARNESS_ARGS" ]; then
+    echo "Harness '$DEJIMA_HARNESS_NAME' declares no no_confirm_args." >&2
+    echo "dejima runs unattended; a harness that stops to ask cannot be run that" >&2
+    echo "way. See \"What a harness must be able to do\" in docs/development.md." >&2
+    exit 1
+fi
+export SANDBOX_HARNESS_COMMAND SANDBOX_HARNESS_REAL SANDBOX_HARNESS_ARGS \
+    SANDBOX_HARNESS_SETTINGS
+
+# [core] command defaults to the selected harness's own command rather than
+# to a literal in core's schema, which is where `claude` used to sit.
+[ -n "$SANDBOX_CMD" ] || SANDBOX_CMD="$SANDBOX_HARNESS_COMMAND"
+export SANDBOX_CMD
 # docker-compose.yml/entrypoint.sh compare these against "1"/"0", not
 # "on"/"off" - config_get_bool is what produces that, config_get would pass
 # "on"/"off" straight through and (among other things) silently disable the
@@ -1082,34 +1126,14 @@ if [ -d "$WORKSPACE_DIR/.git/hooks" ]; then
     extra_mounts+=(-v "$WORKSPACE_DIR/.git/hooks:$WORKSPACE_DIR/.git/hooks:ro")
 fi
 
-# ~/.claude/projects, one slug at a time: the tree is every project's
-# transcripts and memory, and memory is loaded into context at session start,
-# so a write into another slug is background a future session there believes
-# (#104). projects/ itself stays container-local, so an unmounted slug is
-# still writable and just does not survive - which is how Claude Code creates
-# a slug it does not find. Existing slugs only, apart from the workspace's
-# own, so a checkout full of worktrees does not litter the host with empty
-# directories for worktrees nothing has run in.
-mkdir -p "$HOME/.claude/projects/$(ws_slug "$WORKSPACE_DIR")"
-while IFS= read -r _slug; do
-    [ -n "$_slug" ] || continue
-    [ -d "$HOME/.claude/projects/$_slug" ] || continue
-    extra_mounts+=(-v "$HOME/.claude/projects/$_slug:$HOME/.claude/projects/$_slug")
-done < <(workspace_slugs_sorted "$WORKSPACE_DIR")
-
-# ~/.claude/file-history, same shape, sharper reason: `<session>/<hash>@v1`
-# is a verbatim copy of an edited file, so the tree is other projects' source
-# rather than a record of it, and it was writable - tampering there puts
-# chosen content into a later restore. Keyed by session id, so there is no
-# slug to match on; workspace_session_ids resolves it through the transcript
-# names. The starting session's id cannot be known yet, so its directory is
-# container-local: undo history for it is lost if it is resumed on the host.
-mkdir -p "$HOME/.claude/file-history"
-while IFS= read -r _sid; do
-    [ -n "$_sid" ] || continue
-    [ -d "$HOME/.claude/file-history/$_sid" ] || continue
-    extra_mounts+=(-v "$HOME/.claude/file-history/$_sid:$HOME/.claude/file-history/$_sid")
-done < <(workspace_session_ids "$HOME/.claude/projects" "$WORKSPACE_DIR")
+# The state this harness keeps on the host, and which of it this workspace
+# is entitled to see. Harness-specific by nature - which directories exist,
+# and what decides that one of their entries belongs to this workspace, is a
+# fact about the harness rather than about dejima - so it lives in the
+# harness plugin, which declares each mount through emit_mount. The guarded-
+# store refusal runs there, at the point of declaration, rather than being
+# something each plugin has to remember. See bin/dejima-harness-lib.sh.
+harness_hook harness_state_mounts "$WORKSPACE_DIR"
 
 # statusline.sh is executed on the host by Claude Code (settings.json's
 # statusLine.command), so it is staged for entrypoint.sh to copy rather than
@@ -1351,24 +1375,23 @@ if remote_enabled; then
     # own ID.
     extra_mounts+=(-e "DEJIMA_RUN_ID=$DEJIMA_RUN_ID")
 
-    # The notify hook is registered per session, into the override layer from
-    # above and nowhere else: registering it in the operator's real
-    # settings.json would run it for every sandbox and for the host's own
-    # Claude Code, which share that file, when it is only meaningful for a
-    # session that has a marker directory. $SANDBOX_SETTINGS_FILE is
-    # already a throwaway mktemp file, so this rewrite cannot reach the
-    # operator's real settings.json; it is mounted read-only, so the
-    # session cannot unregister itself either. Claude Code merges hooks
-    # across settings layers rather than letting the higher one replace the
-    # lower, so these are added to whatever the operator already has rather
-    # than displacing it. $HOME is left unexpanded for Claude Code to resolve
-    # at hook-run time - inside the container, not here - matching the
-    # convention install.sh already uses.
-    SANDBOX_REMOTE_SETTINGS_TMP="$(mktemp "${TMPDIR:-/tmp}/dejima-settings-remote.XXXXXX.json")"
-    jq '.hooks.Notification = ((.hooks.Notification // []) + [{"matcher": "", "hooks": [{"type": "command", "command": "$HOME/.claude/hooks/dejima-notify.sh waiting"}]}])
-      | .hooks.Stop = ((.hooks.Stop // []) + [{"matcher": "", "hooks": [{"type": "command", "command": "$HOME/.claude/hooks/dejima-notify.sh done"}]}])' \
-        "$SANDBOX_SETTINGS_FILE" > "$SANDBOX_REMOTE_SETTINGS_TMP"
-    mv "$SANDBOX_REMOTE_SETTINGS_TMP" "$SANDBOX_SETTINGS_FILE"
+    # Registered per session, into the override layer from above and nowhere
+    # else: putting it in the operator's real settings.json would run it for
+    # every sandbox and for the host's own agent, which share that file, when
+    # it is only meaningful for a session that has a marker directory.
+    # $SANDBOX_SETTINGS_FILE is already a throwaway mktemp file, so this
+    # rewrite cannot reach the operator's real settings; it is mounted
+    # read-only, so the session cannot unregister itself either.
+    #
+    # How a harness is told to run something on those two events is the
+    # harness's own business - Claude Code merges hook entries across
+    # settings layers, another harness may take a config key or an
+    # environment variable - so the writing is the plugin's. Whether it
+    # happens at all is core's, and is gated on the harness having declared
+    # the notify guard.
+    if harness_has_guard notify; then
+        harness_hook harness_register_notify "$SANDBOX_SETTINGS_FILE"
+    fi
 fi
 
 # Everything from here to the container's own first output is silent: the
@@ -1382,6 +1405,12 @@ printf '%sdejima%s is starting, please wait...\n' "$C_KEY" "$C_RESET" >&2
 printf '%sA first run builds the container image, which takes several minutes.%s\n' \
     "$C_DIM" "$C_RESET" >&2
 
+# Named here, once, at the moment the operator is choosing to proceed. Silent
+# when the harness hosts every guard, so this is not a line anyone learns to
+# scroll past - it appears only when a protection they have elsewhere is
+# genuinely not in force here.
+harness_report_guards "$DEJIMA_HARNESS_NAME"
+
 # Snapshot host-persistence surfaces so the post-run audit can report
 # anything that changed while this session ran (advisory - see bin/dejima-audit).
 "$SCRIPT_DIR/dejima-audit" snapshot "$WORKSPACE_DIR" "$SANDBOX_AUDIT_STATE" || true

bin/dejima-audit

@@ -14,6 +14,8 @@ source "$(dirname "$(readlink -f "$0")")/dejima-provider-lib.sh"
 source "$(dirname "$(readlink -f "$0")")/dejima-color-lib.sh"
 # shellcheck source=dejima-slug-lib.sh
 source "$(dirname "$(readlink -f "$0")")/dejima-slug-lib.sh"
+# shellcheck source=dejima-harness-lib.sh
+source "$(dirname "$(readlink -f "$0")")/dejima-harness-lib.sh"
 # Defined empty here so every interpolation below is safe before a surface
 # picks its stream; compare (stderr) and ack (stdout) each re-init for theirs.
 color_init 1
@@ -21,17 +23,36 @@ config_validate || exit 1
 
 cmd="${1:-}"; ws_arg="${2:-}"; state="${3:-}"
 
-PROJECTS_DIR="$(config_get harness.claude-code projects_dir)"
+PROJECTS_DIR="$(harness_config_get projects_dir)"
 
-# The one top-level ~/.claude entry docker-compose.yml's read-only overlays
-# don't cover (settings.json/CLAUDE.md/plugins/hooks/skills/commands/agents/
-# output-styles all are) - settings.json's statusLine.command runs it on the
-# HOST, unsandboxed, and bin/dejima's own read-only mount onto it
-# doesn't reliably protect it when it's a symlink (the common case - runc
-# resolves the mount destination through the symlink; confirmed against a
-# live container, see test/runtime.bats). Detection here is the compensating
-# control for that gap. Overridable for tests.
-STATUSLINE_PATH="$(config_get harness.claude-code statusline_path)"
+# The paths the selected harness causes to run ON THE HOST, unsandboxed,
+# from configuration a session can reach - Claude Code's statusline is the
+# instance that exists. Each is watched on its own rather than folded into
+# hash_paths, because bin/dejima's read-only mount does not reliably protect
+# one that is a symlink (the common case - runc resolves the mount
+# destination through the link; confirmed against a live container, see
+# test/runtime.bats), so detection here is the compensating control.
+#
+# Declared by the harness's plugin, not by its manifest: the labels below
+# are the fixed prefixes `ack` strips to recover an id, which makes them
+# part of a parser's grammar rather than data. See bin/dejima-harness-lib.sh.
+harness_plugin_load "$(config_get core harness)"
+host_exec_load
+
+# With no harness selected there is no statusline path to watch, and the
+# compensating control above quietly covers nothing. bin/dejima refuses to
+# start without [core] harness, so a snapshot in this state means the audit
+# was driven by hand against a config dejima itself would reject - say so
+# rather than reporting a clean run over a surface that was never examined.
+# A silently narrower audit is worse than a noisy one.
+if [ "${#DEJIMA_HOST_EXEC[@]}" -eq 0 ] && [ -z "$(config_get core harness)" ]; then
+    case "$cmd" in
+        snapshot|compare)
+            echo "dejima audit: no [core] harness is set, so harness-specific surfaces" >&2
+            echo "              (whatever this harness runs on the host) are NOT checked." >&2
+            ;;
+    esac
+fi
 
 # This script's own repo root - the sandbox's trusted computing base (see
 # tcb_snapshot below) is only monitored when the workspace being audited IS
@@ -369,11 +390,14 @@ withhold() { printf '%s\n' "$2" > "$1" 2>/dev/null || true; }
 # compare against.
 existed_before() {
     local rid="$1" range enc
+    if host_exec_is_id "$rid"; then
+        range='/^### hostexec/,$p'; enc="$(enc_id "${rid#*:}")"
+    else
     case "$rid" in
-        statusline:*) range='/^### statusline/,$p';           enc="$(enc_id "${rid#statusline:}")" ;;
-        tcb:*)        range='/^### tcb/,/^### statusline/p';   enc="$(enc_id "${rid#tcb:}")" ;;
+        tcb:*)        range='/^### tcb/,/^### hostexec/p';    enc="$(enc_id "${rid#tcb:}")" ;;
         *)            range='/^### paths/,/^### projects/p';   enc="$(enc_id "$rid")" ;;
     esac
+    fi
     sed -n "$range" "$state" | grep -v '^### ' | cut -f1 | grep -qxF -- "$enc"
 }
 
@@ -518,11 +542,15 @@ promote_finding() {
     # Mirrors current_content_for_id's dispatch; gitconfig ids never reach
     # here (promote_gitconfig returned above), and stat does not follow a
     # symlink, whose rendering is its target string rather than its content.
+    # A host-execution surface's path comes from the harness plugin that
+    # declared it, not from the workspace.
+    local _hp
+    if _hp="$(host_exec_path_for_id "$rid")"; then src="$_hp"; else
     case "$rid" in
-        statusline:*) src="$STATUSLINE_PATH" ;;
         tcb:*)        src="$ws/${rid#tcb:}" ;;
         *)            src="$ws/$rid" ;;
     esac
+    fi
     csz="$(stat -c %s "$src" 2>/dev/null)" || csz=0
     if [ "$csz" -gt "$STAGE_FILE_CAP" ]; then
         withhold "$sc/$key.withheld" "change too large to retain - compare by hand"
@@ -661,7 +689,7 @@ id_severity() {
         gitconfig:*) k="${1#gitconfig:}"; k="${k#worktree:}"
                      is_exec_key "$k" && { echo CRITICAL; return; }
                      case "$k" in alias.*) echo CRITICAL ;; *) echo WARNING ;; esac ;;
-        statusline:*|tcb:*) echo CRITICAL ;;
+        tcb:*) echo CRITICAL ;;
         *) path_severity "$1" ;;
     esac
 }
@@ -897,13 +925,14 @@ gitconfig_sha_for_key() {
 # that namespace, so the id/sha pair ack records is exactly what
 # baseline_suppresses will later compare against.
 current_sha_for_id() {
-    local id="$1" f
+    local id="$1" f _hp
+    if _hp="$(host_exec_path_for_id "$id")"; then f="$_hp"; else
     case "$id" in
         gitconfig:*)  gitconfig_sha_for_key "$ws" "${id#gitconfig:}"; return ;;
-        statusline:*) f="$STATUSLINE_PATH" ;;
         tcb:*)        f="$ws/${id#tcb:}" ;;
         *)            f="$ws/$id" ;;
     esac
+    fi
     # -e alone follows a symlink and misses one whose target is gone - but a
     # dangling symlink is exactly what hash_entry() below can still hash (the
     # link's target string, never the target's content), so excluding it here
@@ -924,13 +953,14 @@ DISPLAY_LINE_CAP=40
 # as their target, because that is what hash_entry() hashes for them - the
 # link's own content is not what changed.
 current_content_for_id() {
-    local id="$1" f
+    local id="$1" f _hp
+    if _hp="$(host_exec_path_for_id "$id")"; then f="$_hp"; else
     case "$id" in
         gitconfig:*)  gitconfig_value_for_key "$ws" "${id#gitconfig:}" ;;
-        statusline:*) f="$STATUSLINE_PATH" ;;
         tcb:*)        f="$ws/${id#tcb:}" ;;
         *)            f="$ws/$id" ;;
     esac
+    fi
     case "$id" in gitconfig:*) return ;; esac
     [ -e "$f" ] || [ -L "$f" ] || return 1
     if [ -L "$f" ]; then
@@ -999,10 +1029,13 @@ show_capped() {
 # Never sanitized through a path that would make it unfindable: it is the
 # audit's OWN text about a location, not workspace-controlled content.
 source_hint() {
-    local id="$1"
+    local id="$1" _hp
+    if _hp="$(host_exec_path_for_id "$id")"; then
+        printf '%s\n' "    (full text: $(sanitize "$_hp"))"
+        return
+    fi
     case "$id" in
         gitconfig:*)  printf '%s\n' "    (full value: git -C $ws config --get $(sanitize "${id#gitconfig:}"))" ;;
-        statusline:*) printf '%s\n' "    (full text: $STATUSLINE_PATH)" ;;
         tcb:*)        printf '%s\n' "    (full text: $ws/$(sanitize "${id#tcb:}"))" ;;
         *)            printf '%s\n' "    (full text: $ws/$(sanitize "$id"))" ;;
     esac
@@ -1050,20 +1083,33 @@ render_finding() {
     return 0
 }
 
-statusline_snapshot() {
-    # path<TAB>sha for $HOME/.claude/statusline.sh, or nothing if this host
-    # has none - see STATUSLINE_PATH above for why this one path is
-    # monitored on its own rather than as part of hash_paths.
-    local f="$1"
-    [ -e "$f" ] || return 0
-    stage_entry "statusline:statusline.sh" "$f"
-    printf 'statusline.sh\t%s\n' "$(hash_entry "$f")"
+host_exec_snapshot() {
+    # leaf<TAB>sha for every host-execution surface the harness declared, or
+    # nothing where the host has none. One line per surface, keyed by the
+    # leaf so the id a baseline stores ("<namespace>:<leaf>") is unchanged
+    # for a harness already in use.
+    local rec ns leaf path label
+    for rec in ${DEJIMA_HOST_EXEC[@]+"${DEJIMA_HOST_EXEC[@]}"}; do
+        IFS=$'\t' read -r ns leaf path label <<< "$rec"
+        [ -n "$path" ] && [ -e "$path" ] || continue
+        stage_entry "$ns:$leaf" "$path"
+        printf '%s\t%s\n' "$leaf" "$(hash_entry "$path")"
+    done
 }
 
 case "$cmd" in
     --print-paths)
-        printf 'projects_dir=%s\nstatusline_path=%s\naudit_dir=%s\nbaselines_dir=%s\nkeep=%s\n' \
-            "$PROJECTS_DIR" "$STATUSLINE_PATH" "$AUDIT_DIR" "$BASELINE_DIR" "$AUDIT_KEEP"
+        # statusline_path is still named, because it is the surface this
+        # harness declares and existing callers read it by that name. It
+        # comes from the declaration now rather than from a global of its
+        # own, so a harness declaring none prints an empty value and one
+        # declaring several prints a line each.
+        printf 'projects_dir=%s\naudit_dir=%s\nbaselines_dir=%s\nkeep=%s\n' \
+            "$PROJECTS_DIR" "$AUDIT_DIR" "$BASELINE_DIR" "$AUDIT_KEEP"
+        for _rec in ${DEJIMA_HOST_EXEC[@]+"${DEJIMA_HOST_EXEC[@]}"}; do
+            IFS=$'\t' read -r _ns _leaf _path _label <<< "$_rec"
+            printf '%s_path=%s\n' "$_ns" "$_path"
+        done
         exit 0
         ;;
     snapshot)
@@ -1081,7 +1127,7 @@ case "$cmd" in
           # version unparseable by the other across an upgrade mid-session.
           echo "### projects";
           echo "### tcb";       tcb_snapshot "$ws";
-          echo "### statusline"; statusline_snapshot "$STATUSLINE_PATH"; } > "$state" 2>/dev/null || true
+          echo "### hostexec"; host_exec_snapshot; } > "$state" 2>/dev/null || true
         exit 0
         ;;
     compare)
@@ -1120,7 +1166,7 @@ case "$cmd" in
                            echo "### paths";     hash_paths "$ws";
                            echo "### projects";
                            echo "### tcb";       tcb_snapshot "$ws";
-                           echo "### statusline"; statusline_snapshot "$STATUSLINE_PATH"; } > "$new" 2>/dev/null || {
+                           echo "### hostexec"; host_exec_snapshot; } > "$new" 2>/dev/null || {
             echo "dejima audit: could not complete, skipping." >&2; rm -f "$new"; exit 0; }
 
         # One raw namespaced id per finding whose surface has retainable
@@ -1225,7 +1271,7 @@ case "$cmd" in
         # tcb diffs: any change under the sandbox's own trusted computing
         # base, only populated when this session's workspace IS the
         # sandbox's own repo (see tcb_snapshot) - empty/no-op otherwise.
-        # Bounded at ### statusline (not $p, the last section now) so this
+        # Bounded at ### hostexec (not $p, the last section now) so this
         # doesn't also swallow that section's lines.
         # Split on whether git can see the change, because that decides
         # whether this finding is telling the operator anything.
@@ -1252,25 +1298,39 @@ case "$cmd" in
             fi
             crit+=("TCB (sandbox self) modified, INVISIBLE to git: $line")
             finding_ids+=("$tid")
-        done < <(comm -3 <(sed -n '/^### tcb/,/^### statusline/p' "$state" | grep -v '^### ') \
-                         <(sed -n '/^### tcb/,/^### statusline/p' "$new"   | grep -v '^### ') \
+        done < <(comm -3 <(sed -n '/^### tcb/,/^### hostexec/p' "$state" | grep -v '^### ') \
+                         <(sed -n '/^### tcb/,/^### hostexec/p' "$new"   | grep -v '^### ') \
                  | sed 's/^\t//' | cut -f1 | sort -u )
         if [ "$tcb_visible" -gt 0 ]; then
             info+=("$tcb_visible change(s) under the sandbox's own bin/, hooks/, docker/, test/ - this workspace IS dejima; review them with git")
         fi
 
-        # statusline diff: ~/.claude/statusline.sh added/changed/removed/
-        # repointed - see STATUSLINE_PATH above for why this gets its own
-        # section instead of folding into hash_paths. Worded at least as
-        # strongly as COMMAND-EXECUTION/TCB above: this is unsandboxed host
-        # code execution, not just a config change.
+        # host-execution diff: a path the harness runs on the HOST added,
+        # changed, removed or repointed. Its own section rather than folded
+        # into hash_paths for the reason given where the surfaces are loaded,
+        # and worded at least as strongly as COMMAND-EXECUTION/TCB above:
+        # this is unsandboxed host code execution, not just a config change.
+        #
+        # The label is the plugin's, because it is the fixed prefix `ack`
+        # strips to recover the id and so belongs in trusted code rather than
+        # in manifest data. A leaf with no declaring surface cannot happen
+        # from a snapshot this run wrote, but it can from a state file
+        # written before the harness changed - such a line is skipped rather
+        # than reported under a label nothing owns.
         while IFS= read -r line; do
-            sid="statusline:$line"; ssha=""; [ -e "$STATUSLINE_PATH" ] && ssha="$(hash_entry "$STATUSLINE_PATH")"
+            _hl=""; _hns=""; _hpath=""
+            for _rec in ${DEJIMA_HOST_EXEC[@]+"${DEJIMA_HOST_EXEC[@]}"}; do
+                IFS=$'\t' read -r _ns _leaf _path _label <<< "$_rec"
+                [ "$_leaf" = "$line" ] || continue
+                _hns="$_ns"; _hpath="$_path"; _hl="$_label"; break
+            done
+            [ -n "$_hl" ] || continue
+            sid="$_hns:$line"; ssha=""; [ -e "$_hpath" ] && ssha="$(hash_entry "$_hpath")"
             baseline_suppresses "$sid" "$ssha" && continue
-            crit+=("HOST-CODE-EXECUTION statusline.sh changed (runs UNSANDBOXED on the host via settings.json statusLine.command): $(enc_id "$line")")
+            crit+=("$_hl$(enc_id "$line")")
             finding_ids+=("$sid")
-        done < <(comm -3 <(sed -n '/^### statusline/,$p' "$state" | grep -v '^### ') \
-                         <(sed -n '/^### statusline/,$p' "$new"   | grep -v '^### ') \
+        done < <(comm -3 <(sed -n '/^### hostexec/,$p' "$state" | grep -v '^### ') \
+                         <(sed -n '/^### hostexec/,$p' "$new"   | grep -v '^### ') \
                  | sed 's/^\t//' | cut -f1 | sort -u )
 
         rm -f "$new"
@@ -1544,6 +1604,27 @@ case "$cmd" in
             # from $id because a gitconfig body carries `key=value` while its
             # id is the key alone.
             ackable=0; id=""; rid=""; lbl=""; surface=""
+            # Host-execution surfaces first, because their labels come from
+            # the harness plugin rather than from a literal here. Matched by
+            # an exact prefix strip - "$body" with the label removed differs
+            # from "$body" only when the label really is at position 0 -
+            # rather than by a `case` pattern, which would treat a label's
+            # own characters as globs. Anchoring is the whole point (#45):
+            # an unanchored match lets chosen text derive an id in the wrong
+            # namespace, and approving it baselines an id that never matches
+            # while the real finding counts as acknowledged.
+            for _rec in ${DEJIMA_HOST_EXEC[@]+"${DEJIMA_HOST_EXEC[@]}"}; do
+                IFS=$'\t' read -r _ns _leaf _path _label <<< "$_rec"
+                _rest="${body#"$_label"}"
+                [ "$_rest" != "$body" ] || continue
+                ackable=1; lbl="$_label"; surface="$_rest"
+                id="$_ns:$_rest"; rid="$_ns:$(dec_id "$_rest")"
+                break
+            done
+            # Only if none of them claimed it: a host-exec label that
+            # matched has already derived the id, and the arms below must
+            # not get a second go at the same text.
+            if [ -z "$id" ]; then
             case "$body" in
                 "HOST-CODE-EXECUTION workspace file: "*)
                     ackable=1; lbl="HOST-CODE-EXECUTION workspace file: "
@@ -1571,11 +1652,6 @@ case "$cmd" in
                     cfgline="${body#changed git config: }"
                     ekey="${cfgline%%=*}"; surface="$ekey"
                     id="gitconfig:$ekey"; rid="gitconfig:$(dec_id "$ekey")" ;;
-                "HOST-CODE-EXECUTION statusline.sh changed (runs UNSANDBOXED on the host via settings.json statusLine.command): "*)
-                    ackable=1; lbl="HOST-CODE-EXECUTION statusline.sh changed (runs UNSANDBOXED on the host via settings.json statusLine.command): "
-                    esl="${body#HOST-CODE-EXECUTION statusline.sh changed (runs UNSANDBOXED on the host via settings.json statusLine.command): }"
-                    surface="$esl"
-                    id="statusline:$esl"; rid="statusline:$(dec_id "$esl")" ;;
                 "TCB (sandbox self) modified, INVISIBLE to git: "*)
                     ackable=1; lbl="TCB (sandbox self) modified, INVISIBLE to git: "
                     etcb="${body#TCB (sandbox self) modified, INVISIBLE to git: }"
@@ -1583,6 +1659,7 @@ case "$cmd" in
                     id="tcb:$etcb"; rid="tcb:$(dec_id "$etcb")" ;;
                 *) ackable=0 ;;
             esac
+            fi
             # Defence in depth: even an anchored arm above should never
             # leave id empty while claiming ackable, but don't trust that -
             # crit_acked (and thus whether a report can shed -CRITICAL.txt)

bin/dejima-config-lib.sh

@@ -42,7 +42,7 @@ _config_table() {
 core.harness	provider:harness
 core.forge	provider:forge	none
 core.workflow	provider:workflow	local-only
-core.command	identifier	claude
+core.command	?identifier
 core.firewall	bool	on
 core.share_dir	path	~/.local/share/dejima/shared
 core.ssh_key	?path

bin/dejima-epitaph

@@ -29,7 +29,7 @@ cmd="${1:-}"; ws_arg="${2:-}"; transcripts="${3:-}"
 
 [ "$(config_get epitaph enabled)" = "on" ] || exit 0
 STORE="$(config_get epitaph dir)"
-[ -n "$transcripts" ] || transcripts="$(config_get harness.claude-code projects_dir)"
+[ -n "$transcripts" ] || transcripts="$(harness_config_get projects_dir)"
 
 ws="$ws_arg"
 [ -n "$ws" ] || ws="$(pwd)"

bin/dejima-harness-lib.sh

@@ -0,0 +1,241 @@
+# Shared library: loading a harness plugin, and the interface it declares
+# through. Sourced by bin/dejima. Not on PATH and not executable.
+#
+# Three tiers, and which one a thing belongs in is the whole design:
+#
+#   core      - the mechanism, and every enforcement point.
+#   manifest  - data. harnesses/<name>/harness.conf. Never sourced, never
+#               executed. Selects among named core mechanisms, supplies paths.
+#   plugin    - bin/harness/<name>.sh. The harness-specific remainder, as
+#               code, in this repository, supported one harness at a time.
+#
+# A feature belongs in the manifest if it can be stated as a value. It moves
+# here only when it cannot: opencode resolving its state directory through a
+# database, Claude Code pairing file-history to transcripts by session id.
+# "Add a manifest key" is the answer until it demonstrably is not.
+#
+# Plugins live under bin/ rather than beside their manifest because
+# dejima-audit's tcb_snapshot covers install.sh, bin/, hooks/, docker/ and
+# test/ - and not harnesses/. Host-side plugin code under harnesses/ would be
+# code that runs on the host and that a session could edit in dejima's own
+# checkout without raising a CRITICAL, which is the exact class the audit
+# exists to catch. Under bin/ it is covered for free, and "manifests are
+# data, never executed" (docs/security.md) stays true word for word.
+#
+# Plugins are SOURCED, not invoked. They are part of the trusted computing
+# base, so the risk worth designing against is not a careless plugin - it is
+# three plugins implementing the security model three different ways.
+# Sourcing lets a plugin use core's own primitives (_refuse_guarded_mount,
+# sanitize, ws_slug, harness_config_get) rather than re-deriving them, which
+# is what keeps one security model instead of one per harness. An invoked
+# protocol would also put a new text parser on the launch path, and every
+# parsing bug this repository has had is in that family.
+#
+# The rule that replaces isolation: A PLUGIN COMPUTES, CORE ENFORCES.
+# A plugin declares through the emit_* functions below, which validate at the
+# point of declaration. It never touches extra_mounts itself - a static test
+# holds that, because a plugin that appended directly would skip the guarded-
+# store refusal, and would skip it differently in each harness.
+
+# The hooks core will call. A plugin defines the ones its harness needs and
+# omits the rest; anything else it defines is a name core does not call, and
+# the static test refuses it rather than letting it look wired up.
+DEJIMA_HARNESS_HOOKS="harness_state_mounts harness_register_notify harness_register_guards harness_host_exec_surfaces"
+
+# What an operator loses when a harness cannot host a given guard. The set
+# itself is DEJIMA_KNOWN_GUARDS in dejima-provider-lib.sh, next to the
+# manifest schema and the validation that rejects a name outside it: a
+# constant the validation depends on must live where the validation does, or
+# a caller that loads only provider-lib validates against an empty set and
+# rejects every guard there is.
+_guard_description() {
+    case "$1" in
+        bash-deny)   printf 'obviously destructive shell commands are not refused' ;;
+        push-guard)  printf 'pushes to hosts and branches outside the allowed set are not refused' ;;
+        merge-guard) printf 'the agent can merge its own pull requests' ;;
+        notify)      printf 'remote access gets no waiting/done notifications' ;;
+        *)           printf 'unknown guard' ;;
+    esac
+}
+
+# Whether the selected harness declared a given guard. Core gates the work
+# on this rather than on whether the plugin happens to define a hook: a
+# harness that forgot the declaration but implemented the hook would get a
+# guard the launch message has just told the operator it does not have.
+harness_has_guard() {
+    case " $(manifest_get harness "$DEJIMA_HARNESS_NAME" guards) " in
+        *" $1 "*) return 0 ;;
+        *) return 1 ;;
+    esac
+}
+
+# Says which guards the selected harness cannot host. Silent when it hosts
+# them all, which is the common case and must not become noise an operator
+# learns to scroll past - the point is that the line only appears when
+# something really is missing.
+harness_report_guards() {
+    local harness="$1" declared guard missing=()
+    declared="$(manifest_get harness "$harness" guards)"
+    for guard in $DEJIMA_KNOWN_GUARDS; do
+        case " $declared " in
+            *" $guard "*) ;;
+            *) missing+=("$guard") ;;
+        esac
+    done
+    [ "${#missing[@]}" -gt 0 ] || return 0
+    printf '  %sharness %s does not support %s of dejima'"'"'s guards:%s\n' \
+        "$C_WARN" "$harness" "${#missing[@]}" "$C_RESET" >&2
+    for guard in "${missing[@]}"; do
+        printf '    %s%s%s - %s\n' "$C_KEY" "$guard" "$C_RESET" "$(_guard_description "$guard")" >&2
+    done
+    printf '  The container still bounds this session; these are the fast-fail\n' >&2
+    printf '  guards it does not get. See docs/development.md.\n' >&2
+}
+
+# Sources the selected harness's plugin. Hard error when it is missing:
+# support is per harness and deliberate (see "Adding a new harness" in
+# docs/development.md), so a harness with a manifest and no plugin is a
+# half-finished integration rather than a lightweight one.
+harness_plugin_load() {
+    local name="$1" plugin
+    [ -n "$name" ] || return 0
+    # Resolved from this file's own location, not from a caller's SCRIPT_DIR:
+    # install.sh sets that to the repo root while bin/dejima sets it to bin/,
+    # and a library that only works for one of its callers is a trap for the
+    # next one.
+    plugin="$(cd "${BASH_SOURCE[0]%/*}" && pwd)/harness/$name.sh"
+    if [ ! -f "$plugin" ]; then
+        echo "No harness plugin for '$name' at $plugin." >&2
+        echo "A supported harness has both a manifest and a plugin; see" >&2
+        echo "\"Adding a new harness\" in docs/development.md." >&2
+        exit 1
+    fi
+    # shellcheck disable=SC1090
+    source "$plugin"
+}
+
+# Calls one hook of the loaded plugin, if it defines it. Absence is normal:
+# not every harness needs every hook, and the manifest is where a harness
+# says what it cannot do at all.
+harness_hook() {
+    local hook="$1"; shift
+    declare -F "$hook" >/dev/null 2>&1 || return 0
+    "$hook" "$@"
+}
+
+# --- what a plugin declares through --------------------------------------
+#
+# Each of these validates and then appends to core's own state. A plugin
+# calls them; it does not reach past them.
+
+# A host path mounted into the container at the same path. $2 is the mode
+# ("ro", or empty for read-write).
+#
+# The guarded-store refusal runs here, at the point of declaration, so it
+# cannot be skipped by a plugin that forgot it: a harness state directory
+# that overlapped the approval or audit or epitaph store would otherwise
+# hand a session exactly what those stores exist to withhold, and a harness
+# is precisely the kind of thing whose paths are computed rather than
+# written down.
+emit_mount() {
+    local path="$1" mode="${2:-}"
+    [ -n "$path" ] || return 0
+    case "$path" in
+        *:*)
+            echo "Harness plugin emitted a mount path containing a colon: $path" >&2
+            exit 1 ;;
+    esac
+    _guarded_stores
+    _refuse_guarded_mount "harness state mount" "$path" \
+        ${GUARDED_STORES[@]+"${GUARDED_STORES[@]}"}
+    if [ -n "$mode" ]; then
+        extra_mounts+=(-v "$path:$path:$mode")
+    else
+        extra_mounts+=(-v "$path:$path")
+    fi
+}
+
+# An environment variable for the container. Name-checked because it becomes
+# a `-e NAME=value` argument, and a name carrying a space or an `=` would
+# split into something else entirely.
+emit_env() {
+    local name="$1" value="${2:-}"
+    case "$name" in
+        ''|*[!A-Za-z0-9_]*)
+            echo "Harness plugin emitted an invalid environment variable name: $name" >&2
+            exit 1 ;;
+    esac
+    extra_mounts+=(-e "$name=$value")
+}
+
+# --- host-execution surfaces ---------------------------------------------
+#
+# Paths a harness causes to run ON THE HOST, unsandboxed, from configuration
+# a session can reach. Claude Code's statusline is the instance that exists:
+# settings.json's statusLine.command names a script the host runs, so a
+# session that can write that file has a way onto the host that no container
+# boundary sees.
+#
+# Declared by the plugin rather than by the manifest, and the reason is a
+# trust boundary rather than convenience. dejima-audit's `ack` derives a
+# finding's id by stripping a FIXED label from the front of the finding text
+# - anchored deliberately, because an unanchored match lets chosen text
+# derive an id in the wrong namespace and baseline an approval that never
+# matches while the real finding is counted as acknowledged (#45). Those
+# labels are therefore part of a parser's grammar. Manifests are data, and
+# provider directories are NOT in tcb_snapshot's list, so in the self-mount
+# case a session can edit one without raising a CRITICAL. A plugin is under
+# bin/, which the audit does watch. The label stays a literal in trusted
+# code; it just lives with the harness that owns it.
+#
+# Each surface carries its own namespace, so ids stay stable per harness and
+# no rename is forced on anyone's baseline.
+DEJIMA_HOST_EXEC=()
+
+# namespace, leaf, path, label. The id is "<namespace>:<leaf>", which is what
+# a baseline stores, so neither may change for a harness already in use.
+emit_host_exec() {
+    local ns="$1" leaf="$2" path="$3" label="$4"
+    [ -n "$path" ] || return 0
+    case "$ns" in
+        ''|*[!a-z0-9-]*)
+            echo "Harness plugin emitted an invalid host-exec namespace: $ns" >&2
+            exit 1 ;;
+    esac
+    # The leaf lands in an id, which is compared against baseline entries and
+    # written into a report; a tab or newline in either would split a record.
+    case "$leaf$label" in
+        *$'\t'*|*$'\n'*)
+            echo "Harness plugin emitted a host-exec leaf or label containing a tab or newline" >&2
+            exit 1 ;;
+    esac
+    [ -n "$leaf" ] && [ -n "$label" ] || {
+        echo "Harness plugin emitted a host-exec surface with no leaf or label" >&2
+        exit 1
+    }
+    DEJIMA_HOST_EXEC+=("$ns"$'\t'"$leaf"$'\t'"$path"$'\t'"$label")
+}
+
+# Asks the loaded plugin for its surfaces. Empty when no harness is selected
+# or the harness has none, which is a normal state rather than an error.
+host_exec_load() {
+    DEJIMA_HOST_EXEC=()
+    harness_hook harness_host_exec_surfaces
+}
+
+# The host path behind an id, or nothing if that id is not a host-exec one.
+host_exec_path_for_id() {
+    local id="$1" rec ns leaf path label
+    for rec in ${DEJIMA_HOST_EXEC[@]+"${DEJIMA_HOST_EXEC[@]}"}; do
+        IFS=$'\t' read -r ns leaf path label <<< "$rec"
+        [ "$id" = "$ns:$leaf" ] || continue
+        printf '%s' "$path"
+        return 0
+    done
+    return 1
+}
+
+# Whether an id names a host-execution surface. Used where severity is
+# decided: every one of these is CRITICAL, because the whole category is
+# "runs on the host, outside everything".
+host_exec_is_id() { host_exec_path_for_id "$1" >/dev/null; }

bin/dejima-provider-lib.sh

@@ -141,6 +141,10 @@ EOF
             ;;
         harness) cat <<'EOF'
 command	identifier	claude
+command_path	?path
+guards	?list:identifier
+no_confirm_args	?template
+settings_args	?template
 keys	?list:keyspec
 resume_command	?template
 briefing	?relpath
@@ -426,6 +430,37 @@ _config_extra_spec() {
     return 1
 }
 
+# One key of the SELECTED harness, rather than of a harness named literally
+# at the call site.
+#
+# `keys` is declared per harness, so reading one through a fixed section name
+# makes it a declaration only one harness can ever be read through: a second
+# harness gets selected, gets validated, and is then handed the first one's
+# paths with nothing erroring anywhere. That is a silent wrong answer rather
+# than a failure, which is why it is worth a helper rather than a longer
+# expression at each site.
+#
+# Empty when no harness is selected. bin/dejima refuses to start in that
+# state (there is no default, deliberately - see [core] harness), so it is
+# reachable only from the standalone tools, where a harness-specific path
+# that resolves to nothing is the honest answer for "no harness chosen".
+harness_config_get() {
+    local name
+    name="$(config_get core harness)"
+    [ -n "$name" ] || return 0
+    config_get "harness.$name" "$1"
+}
+
+# Every guard rail dejima knows how to apply. A harness declares which of
+# them it can host, in its manifest's `guards`; the ones it cannot are named
+# at launch (see harness_report_guards) rather than quietly absent.
+#
+# Here rather than in dejima-harness-lib.sh because provider_validate_selection
+# rejects a name outside this set, and a constant the validation depends on
+# has to live where the validation does - providers.bats sources only this
+# file, and against an empty set every guard is unknown.
+DEJIMA_KNOWN_GUARDS="bash-deny push-guard merge-guard notify"
+
 # Enumerates the keys of the SELECTED forge/harness (core.forge/core.harness,
 # falling back to their schema default when no config file exists yet to
 # read a selection from - e.g. an isolated call against a fresh checkout)
@@ -465,6 +500,25 @@ provider_validate_selection() {
     manifest_validate workflow "$workflow" || return 1
     manifest_validate harness "$harness" || return 1
 
+    # Every guard rail dejima knows how to apply. A harness declares which of
+    # them it can host; the ones it cannot are named at launch rather than
+    # quietly absent, because an operator who has them everywhere else would
+    # otherwise have to read a manifest to find out they are gone here.
+    #
+    # A name outside this set is a hard error rather than an unknown guard
+    # treated as absent: a typo would otherwise silently turn a guard off,
+    # which is the failure this whole declaration exists to prevent.
+    local guard
+    for guard in $(manifest_get harness "$harness" guards); do
+        case " $DEJIMA_KNOWN_GUARDS " in
+            *" $guard "*) ;;
+            *)
+                echo "harness '$harness' declares an unknown guard: $guard" >&2
+                echo "Known guards: $DEJIMA_KNOWN_GUARDS" >&2
+                return 1 ;;
+        esac
+    done
+
     caps="$(manifest_get forge "$forge" capabilities)"
     requires="$(manifest_get workflow "$workflow" requires)"
     for need in $requires; do

bin/harness/claude-code.sh

@@ -0,0 +1,232 @@
+# Harness plugin: Claude Code.
+#
+# Sourced by bin/dejima through harness_plugin_load when [core] harness names
+# this harness. Part of the trusted computing base - see the interface notes
+# in bin/dejima-harness-lib.sh for why plugins live here and why they are
+# sourced rather than invoked.
+#
+# What is here is what could not be stated as a manifest value. The paths
+# themselves come from the manifest ([harness.claude-code] projects_dir); the
+# reason this is code is the pairing in the second block, which resolves one
+# directory tree through the filenames of another.
+
+# Registers the waiting/done notification handlers into dejima's settings
+# layer, in the shape Claude Code reads them.
+#
+# Claude Code merges hook entries across settings layers rather than letting
+# the higher one replace the lower, so these are added to whatever the
+# operator already has rather than displacing it. $HOME is left unexpanded
+# for Claude Code to resolve at hook-run time - inside the container, not
+# here - matching the convention install.sh already uses.
+#
+# Written through a temp file and renamed: the destination is the settings
+# layer bin/dejima is about to mount, and a jq that failed partway would
+# otherwise leave the session with a truncated one.
+harness_register_notify() {
+    local settings="$1" tmp
+    tmp="$(mktemp "${TMPDIR:-/tmp}/dejima-settings-remote.XXXXXX.json")"
+    if jq '.hooks.Notification = ((.hooks.Notification // []) + [{"matcher": "", "hooks": [{"type": "command", "command": "$HOME/.claude/hooks/dejima-notify.sh waiting"}]}])
+      | .hooks.Stop = ((.hooks.Stop // []) + [{"matcher": "", "hooks": [{"type": "command", "command": "$HOME/.claude/hooks/dejima-notify.sh done"}]}])' \
+        "$settings" > "$tmp"; then
+        mv "$tmp" "$settings"
+    else
+        rm -f "$tmp"
+        echo "warning: could not register the notification hooks; remote access" >&2
+        echo "will not be told when this session wants attention." >&2
+    fi
+}
+
+# The per-project and per-session state this harness keeps on the host, and
+# which parts of it this workspace is entitled to see.
+harness_state_mounts() {
+    local ws="$1" projects slug sid
+    projects="$(harness_config_get projects_dir)"
+    [ -n "$projects" ] || return 0
+
+    # projects/, one slug at a time: the tree is every project's transcripts
+    # and memory, and memory is loaded into context at session start, so a
+    # write into another slug is background a future session there believes
+    # (#104). projects/ itself stays container-local, so an unmounted slug is
+    # still writable and just does not survive - which is how Claude Code
+    # creates a slug it does not find. Existing slugs only, apart from the
+    # workspace's own, so a checkout full of worktrees does not litter the
+    # host with empty directories for worktrees nothing has run in.
+    mkdir -p "$projects/$(ws_slug "$ws")"
+    while IFS= read -r slug; do
+        [ -n "$slug" ] || continue
+        [ -d "$projects/$slug" ] || continue
+        emit_mount "$projects/$slug"
+    done < <(workspace_slugs_sorted "$ws")
+
+    # file-history, same shape, sharper reason: `<session>/<hash>@v1` is a
+    # verbatim copy of an edited file, so the tree is other projects' source
+    # rather than a record of it, and it was writable - tampering there puts
+    # chosen content into a later restore. Keyed by session id, so there is
+    # no slug to match on; workspace_session_ids resolves it through the
+    # transcript names. The starting session's id cannot be known yet, so its
+    # directory is container-local: undo history for it is lost if it is
+    # resumed on the host.
+    #
+    # The pairing is why the plugin is code, and the split is the design in
+    # miniature: both directories are statable, so both are manifest keys.
+    # What cannot be stated is the rule that a name in one selects an entry
+    # in the other, so that is here.
+    local history
+    history="$(harness_config_get file_history_dir)"
+    [ -n "$history" ] || return 0
+    mkdir -p "$history"
+    while IFS= read -r sid; do
+        [ -n "$sid" ] || continue
+        [ -d "$history/$sid" ] || continue
+        emit_mount "$history/$sid"
+    done < <(workspace_session_ids "$projects" "$ws")
+}
+
+# Puts dejima's guard hooks where Claude Code will find them: symlinked into
+# ~/.claude/hooks, and registered in ~/.claude/settings.json. Run by
+# install.sh, not at launch - this writes the operator's own config, and the
+# operator is who decides to install.
+#
+# $1 is the repo root, $2 the directory to move a displaced file into. Every
+# change is printed as it happens, because it is someone's real config.
+#
+# Each guard is gated on the harness having declared it: a harness declares
+# what it can host (see `guards` in its manifest), and registering something
+# it did not declare would contradict the launch message that says so.
+harness_register_guards() {
+    local repo="$1" backup="$2" settings="$HOME/.claude/settings.json"
+
+    mkdir -p "$HOME/.claude/hooks"
+
+    _link_hook() {
+        local name="$1" src="$repo/hooks/$1" dest="$HOME/.claude/hooks/$1"
+        if [ -L "$dest" ] && [ "$(readlink -f "$dest")" = "$(readlink -f "$src")" ]; then
+            echo "Skipping: $name already linked to this repo's copy"
+            return
+        fi
+        if [ -e "$dest" ] || [ -L "$dest" ]; then
+            mkdir -p "$backup"
+            echo "Moving: existing ~/.claude/hooks/$name to $backup/$name"
+            mv "$dest" "$backup/$name"
+        fi
+        echo "Linking: $name ($src -> $dest)"
+        ln -s "$src" "$dest"
+    }
+
+    # Not a guard: this is R3, the briefing's delivery mechanism, and a
+    # session without it does not know it is in a sandbox.
+    _link_hook sandbox-context.sh
+    harness_has_guard push-guard  && _link_hook git-push-guard.sh
+    harness_has_guard merge-guard && _link_hook merge-guard.sh
+
+    # Symlink from before the gitea-merge-guard.sh -> merge-guard.sh rename
+    # points at a hooks/ path that no longer exists. Only remove it if it is
+    # actually dangling, so an operator's own file at this name is left alone.
+    local old_merge_guard="$HOME/.claude/hooks/gitea-merge-guard.sh"
+    if [ -L "$old_merge_guard" ] && [ ! -e "$old_merge_guard" ]; then
+        echo "Removing: dangling pre-rename symlink $old_merge_guard"
+        rm -f "$old_merge_guard"
+    fi
+
+    # Linked so it exists at a stable path for the read-only ~/.claude/hooks
+    # mount, but deliberately NOT registered below: bin/dejima registers it
+    # per session, into a throwaway settings copy, and only when remote
+    # access is configured. Registering it here would fire it for every
+    # unsandboxed host session too, where it has no marker directory to
+    # write to.
+    harness_has_guard notify && _link_hook dejima-notify.sh
+
+    # deny-dangerous-bash.sh is the one hook that is NOT sandbox-gated: it
+    # has no DEJIMA check, so it applies to the operator's own host sessions
+    # as well. That is deliberate, and it is why it may already be owned by
+    # another install (dotfiles, say) - only claim it if nothing else
+    # provides it, so this repo works standalone without clobbering an
+    # existing setup.
+    if harness_has_guard bash-deny; then
+        local deny_dest="$HOME/.claude/hooks/deny-dangerous-bash.sh"
+        if [ -e "$deny_dest" ] || [ -L "$deny_dest" ]; then
+            echo "Skipping: deny-dangerous-bash.sh already present at $deny_dest (leaving it as-is)"
+        else
+            echo "Linking: deny-dangerous-bash.sh ($repo/hooks/deny-dangerous-bash.sh -> $deny_dest)"
+            ln -s "$repo/hooks/deny-dangerous-bash.sh" "$deny_dest"
+        fi
+    fi
+    echo
+
+    if [ ! -f "$settings" ]; then
+        echo "Creating $settings"
+        echo '{}' > "$settings"
+    fi
+
+    # The registration that went with the symlink removed above. Two things
+    # depend on it going: Claude Code reports a missing hook command on every
+    # session start while it points at a path that no longer exists, and -
+    # until the dedupe below stopped matching it - it also stood in for the
+    # registration it was renamed from, so `_register merge-guard.sh` skipped
+    # and the merge guard was registered nowhere at all. Dropped only when
+    # the path it names is gone, so an operator's own file at that name keeps
+    # its registration, matching the symlink check above.
+    if [ ! -e "$old_merge_guard" ] && jq -e --arg s "/gitea-merge-guard.sh" \
+        '[.hooks.PreToolUse[]?.hooks[]?.command // empty] | any(endswith($s))' \
+        "$settings" >/dev/null 2>&1; then
+        echo "Removing: stale pre-rename gitea-merge-guard.sh registration from $settings"
+        local stale_tmp; stale_tmp=$(mktemp)
+        jq --arg s "/gitea-merge-guard.sh" \
+            '.hooks.PreToolUse = ((.hooks.PreToolUse // [])
+                | map(.hooks = ((.hooks // []) | map(select((.command // "") | endswith($s) | not))))
+                | map(select((.hooks | length) > 0)))' \
+            "$settings" > "$stale_tmp" && mv "$stale_tmp" "$settings"
+    fi
+
+    _register() {
+        local event="$1" matcher="$2" script_name="$3" description="$4"
+        # endswith on the leading slash, not test(): test() is an unanchored
+        # regex, so a hook whose name merely ends in another's - which is what
+        # a rename like gitea-merge-guard.sh -> merge-guard.sh produces - read
+        # as already registered, and the new hook was silently never added.
+        if jq -e --arg s "/$script_name" \
+            "[.hooks.${event}[]?.hooks[]?.command // empty] | any(endswith(\$s))" \
+            "$settings" >/dev/null 2>&1; then
+            echo "Skipping: $script_name already registered as a $event hook"
+            return
+        fi
+        echo "Registering $script_name as a $event hook in $settings ($description)"
+        local tmp
+        tmp=$(mktemp)
+        jq --arg matcher "$matcher" --arg cmd "\$HOME/.claude/hooks/$script_name" \
+            ".hooks.${event} = ((.hooks.${event} // []) + [{\"matcher\": \$matcher, \"hooks\": [{\"type\": \"command\", \"command\": \$cmd}]}])" \
+            "$settings" > "$tmp" && mv "$tmp" "$settings"
+    }
+
+    _register SessionStart "startup|resume|clear|compact" sandbox-context.sh \
+        "injects sandbox context on session start"
+    harness_has_guard push-guard && _register PreToolUse Bash git-push-guard.sh \
+        "blocks pushes outside the allowed host(s)/branches"
+    harness_has_guard merge-guard && _register PreToolUse Bash merge-guard.sh \
+        "blocks the configured forge's merge command inside the sandbox"
+    harness_has_guard bash-deny && _register PreToolUse Bash deny-dangerous-bash.sh \
+        "blocks obviously destructive Bash commands"
+    echo
+    return 0
+}
+
+# What Claude Code causes to run on the HOST, unsandboxed.
+#
+# settings.json's statusLine.command names a script the host executes on
+# every session, so a session that can write that file has a path onto the
+# host that no container boundary sees. bin/dejima stages the file rather
+# than mounting over it, because a :ro mount landing on a symlink - the
+# common case - protects the target and leaves the link replaceable;
+# detecting a change here is the compensating control for that.
+#
+# The namespace and leaf together form the id a baseline stores
+# ("statusline:statusline.sh"), so neither may change while anyone has
+# approvals recorded. The label is the fixed prefix `ack` strips to recover
+# that id, which is why it lives here as a literal rather than in the
+# manifest - see the host-exec notes in bin/dejima-harness-lib.sh.
+harness_host_exec_surfaces() {
+    local p
+    p="$(harness_config_get statusline_path)"
+    emit_host_exec statusline statusline.sh "$p" \
+        "HOST-CODE-EXECUTION statusline.sh changed (runs UNSANDBOXED on the host via settings.json statusLine.command): "
+}

docker/Dockerfile

@@ -265,10 +265,13 @@ RUN npm install -g playwright@${PLAYWRIGHT_VERSION} && \
   npx playwright install chromium
 
 # Copy and set up firewall + DNS-proxy + entrypoint scripts, every forge's
-# CLI helpers, and the claude wrapper that pins
-# --dangerously-skip-permissions. The launched application itself
-# (SANDBOX_CMD, default `claude`) and any editor config for it are supplied
-# at runtime, not baked into the image - see docker-compose.yml/entrypoint.sh.
+# CLI helpers, and the harness wrapper that pins whichever no-confirm flags
+# the selected harness needs. The wrapper is installed under a neutral name:
+# the image is shared across harnesses and the selection is per launch, so
+# entrypoint.sh is what links it into place as the harness's own command.
+# The launched application itself (SANDBOX_CMD) and any editor config for it
+# are supplied at runtime, not baked into the image - see
+# docker-compose.yml/entrypoint.sh.
 COPY docker/fixed-domains.sh /usr/local/bin/
 COPY docker/dns-proxy.sh /usr/local/bin/
 COPY docker/init-firewall.sh /usr/local/bin/
@@ -278,7 +281,7 @@ COPY docker/ulogd.conf /etc/ulogd-sandbox.conf
 COPY docker/sandbox-clipboard.lua /usr/local/share/nvim/runtime/plugin/sandbox-clipboard.lua
 COPY docker/entrypoint.sh /usr/local/bin/
 COPY docker/anthropic-proxy-forwarder.js /usr/local/bin/anthropic-proxy-forwarder.js
-COPY docker/claude-wrapper.sh /usr/local/bin/claude
+COPY docker/harness-wrapper.sh /usr/local/bin/dejima-harness-wrapper
 # Back to root before the first RUN that writes outside /home/node. The npm
 # installs above run as node deliberately; COPY writes as root regardless of
 # USER, so the copies above are unaffected, but the install(1) below is a RUN
@@ -292,7 +295,7 @@ COPY forges/ /tmp/forges/
 RUN find /tmp/forges -type f -path '*/bin/*' -exec install -m 755 {} /usr/local/bin/ \; \
     && rm -rf /tmp/forges
 
-RUN chmod +x /usr/local/bin/dns-proxy.sh /usr/local/bin/init-firewall.sh /usr/local/bin/log-shipper.sh /usr/local/bin/entrypoint.sh /usr/local/bin/claude && \
+RUN chmod +x /usr/local/bin/dns-proxy.sh /usr/local/bin/init-firewall.sh /usr/local/bin/log-shipper.sh /usr/local/bin/entrypoint.sh /usr/local/bin/dejima-harness-wrapper && \
   echo 'export PATH="$PATH:/usr/local/share/npm-global/bin"' > /etc/profile.d/npm-global-path.sh
 
 # Entrypoint runs as root (no USER node here) so it can set up the firewall

docker/claude-wrapper.sh

@@ -1,16 +0,0 @@
-#!/bin/bash
-# Shadows the real `claude` binary (installed under npm-global/bin, later on
-# PATH) so every invocation - interactive shell, or claudecode.nvim's
-# terminal - runs with --dangerously-skip-permissions, without callers
-# needing to know that.
-#
-# The sandbox's settings overrides arrive the same way: as an extra
-# --settings layer rather than by mounting over ~/.claude/settings.json (see
-# docker-compose.yml and #47). That only holds if every entry point passes
-# the flag, and shadowing the binary is what makes it true for the
-# invocations the entrypoint never sees. The file is absent when a container
-# is started without bin/dejima, as test/runtime.bats does.
-settings=()
-[ -f /etc/dejima-settings.json ] && settings=(--settings /etc/dejima-settings.json)
-
-exec /usr/local/share/npm-global/bin/claude --dangerously-skip-permissions "${settings[@]}" "$@"

docker/docker-compose.yml

@@ -68,9 +68,18 @@ services:
       # just live at ~/.gitconfig directly.
       GIT_CONFIG_GLOBAL: ${HOME}/.gitconfig-sandbox/.gitconfig
       ALLOWED_DOMAINS: ${ALLOWED_DOMAINS:-}
-      # What actually runs as the sandbox user - defaults to bare `claude`.
-      # See entrypoint.sh and bin/dejima's SANDBOX_NVIM_CONFIG.
+      # What actually runs as the sandbox user - the selected harness's own
+      # command unless [core] command overrides it. See entrypoint.sh and
+      # bin/dejima's SANDBOX_NVIM_CONFIG.
       SANDBOX_CMD: ${SANDBOX_CMD:-claude}
+      # The selected harness's manifest, resolved host-side: which command
+      # the wrapper shadows, the real binary behind it, the flags that make
+      # the session unattended, and how this harness is told to read dejima's
+      # settings layer. Nothing about a harness is baked into the image.
+      SANDBOX_HARNESS_COMMAND: ${SANDBOX_HARNESS_COMMAND:-}
+      SANDBOX_HARNESS_REAL: ${SANDBOX_HARNESS_REAL:-}
+      SANDBOX_HARNESS_ARGS: ${SANDBOX_HARNESS_ARGS:-}
+      SANDBOX_HARNESS_SETTINGS: ${SANDBOX_HARNESS_SETTINGS:-}
       # Opt-in escape hatch from the default hard GitHub-push block - see
       # init-firewall.sh and git-push-guard.sh. Off unless explicitly set.
       ALLOW_GITHUB_PUSH: ${ALLOW_GITHUB_PUSH:-0}
@@ -161,7 +170,7 @@ services:
       - ${HOME}/.claude/CLAUDE.md:/etc/dejima-claude/CLAUDE.md:ro
       # The sandbox's own settings overrides (sandbox.enabled off, plus the
       # remote-access notify hooks when that's on), generated per run by
-      # bin/dejima and reaching Claude Code as claude-wrapper.sh's
+      # bin/dejima and reaching the harness as harness-wrapper.sh's
       # --settings argument. A container-local path, like the staged config
       # above and for the same reason (#47) - and separate from that staging
       # directory because this file is generated per run rather than copied

docker/entrypoint.sh

@@ -103,6 +103,30 @@ if [ -s "$SANDBOX_SSH_KEY_SRC" ]; then
     export SSH_AUTH_SOCK
 fi
 
+# Put the harness wrapper on PATH under the harness's own command name,
+# ahead of the real binary, so every invocation gets the no-confirm flags -
+# including the ones dejima never sees, an interactive shell or an editor
+# plugin's terminal. Linked here rather than COPYed at build time because
+# the image is shared across harnesses and the selection is per launch.
+#
+# Root-owned in a root-owned directory: the sandbox user must not be able to
+# replace the wrapper with something that drops the flags, or reinstate the
+# real binary's name ahead of it.
+#
+# Skipped when SANDBOX_HARNESS_COMMAND is unset, which is a container started
+# without bin/dejima (test/runtime.bats). Refused when it is set to anything
+# but a bare command name: it becomes a path under /usr/local/bin, and a
+# value with a slash in it would write somewhere else entirely.
+if [ -n "${SANDBOX_HARNESS_COMMAND:-}" ]; then
+    case "$SANDBOX_HARNESS_COMMAND" in
+        */*|.*|'')
+            echo "entrypoint: refusing harness command name: $SANDBOX_HARNESS_COMMAND" >&2
+            exit 1 ;;
+    esac
+    ln -sf /usr/local/bin/dejima-harness-wrapper \
+        "/usr/local/bin/$SANDBOX_HARNESS_COMMAND"
+fi
+
 # ~/.claude config files arrive staged read-only under /etc/dejima-claude
 # (see the mount inventory in docker-compose.yml) and get copied into place
 # here rather than bind-mounted at their real paths. A copy can't be
@@ -292,10 +316,8 @@ fi
 # sudo/setuid path back to root after this, so it can't re-run
 # init-firewall.sh itself to widen the allowlist mid-session.
 #
-# SANDBOX_CMD is what actually runs as that user - defaults to bare `claude`
-# (the wrapped binary on PATH, see claude-wrapper.sh) so a fresh clone of
-# this repo works with no editor setup at all. Override it (e.g. to `nvim`)
-# for a custom editor-driven workflow; pair with SANDBOX_NVIM_CONFIG (see
-# bin/dejima) to bring in a real config for it instead of running
-# unconfigured.
+# SANDBOX_CMD is what actually runs as that user - the selected harness's
+# own command unless [core] command overrides it (e.g. to `nvim`) for an
+# editor-driven workflow; pair that with SANDBOX_NVIM_CONFIG (see bin/dejima)
+# to bring in a real config for it instead of running unconfigured.
 exec gosu "$SANDBOX_USER" ${SANDBOX_CMD:-claude} "$@"

docker/harness-wrapper.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+# Shadows the selected harness's real binary on PATH, so every invocation -
+# the entrypoint's, an interactive shell's, an editor plugin's terminal -
+# runs with the flags dejima requires, without any caller needing to know
+# that.
+#
+# Installed by entrypoint.sh under the harness's own command name rather than
+# COPYed to a fixed one at build time: the image is shared across harnesses
+# and the selection is per launch, so which name to shadow is only known once
+# the container starts.
+#
+# Every value here comes from the selected harness's manifest, resolved on
+# the host (see bin/dejima) and passed in as environment. Nothing about any
+# one harness is written down in this file.
+#
+#   SANDBOX_HARNESS_REAL      the real binary this shadows
+#   SANDBOX_HARNESS_ARGS      the no-confirm flags, without which the agent
+#                             stops to ask and the arrangement becomes a
+#                             worse way of running it on the host
+#   SANDBOX_HARNESS_SETTINGS  how this harness is told to read dejima's own
+#                             settings layer, if it reads one at all
+#
+# The settings layer arrives as an extra layer rather than as a mount over
+# the harness's own config file (docker-compose.yml, #47). That only holds if
+# every entry point passes it, which is what shadowing the binary buys.
+# /etc/dejima-settings.json is absent when a container is started without
+# bin/dejima, as test/runtime.bats does, so its flag stays conditional on the
+# file rather than on the manifest key alone.
+#
+# Word-split deliberately: both carry flags, which have no spaces, and an
+# array is what exec needs. A harness whose flags need quoting has outgrown
+# this and should say so in its plugin.
+set -u
+
+if [ -z "${SANDBOX_HARNESS_REAL:-}" ] || [ ! -x "${SANDBOX_HARNESS_REAL:-}" ]; then
+    echo "dejima: no harness binary at '${SANDBOX_HARNESS_REAL:-<unset>}'." >&2
+    echo "dejima: command_path in the harness manifest is what names it." >&2
+    exit 127
+fi
+
+args=()
+# shellcheck disable=SC2206
+[ -n "${SANDBOX_HARNESS_ARGS:-}" ] && args=(${SANDBOX_HARNESS_ARGS})
+
+settings=()
+# shellcheck disable=SC2206
+[ -n "${SANDBOX_HARNESS_SETTINGS:-}" ] && [ -f /etc/dejima-settings.json ] \
+    && settings=(${SANDBOX_HARNESS_SETTINGS})
+
+exec "$SANDBOX_HARNESS_REAL" \
+    ${args[@]+"${args[@]}"} ${settings[@]+"${settings[@]}"} "$@"

docs/configuration.md

@@ -27,6 +27,7 @@ what a given launch will actually use.
 | `[core] ssh_key` | unset | dedicated deploy key for headless/unattended git push |
 | `[core] known_hosts` | `~/.ssh/known_hosts` | known-hosts file used for git-over-ssh |
 | `[harness.claude-code] projects_dir` | `~/.claude/projects` | where Claude Code session transcripts live |
+| `[harness.claude-code] file_history_dir` | `~/.claude/file-history` | Claude Code's edit-undo record, mounted per session rather than whole |
 | `[harness.claude-code] statusline_path` | `~/.claude/statusline.sh` | statusline script path |
 | `[forge.gitea] ssh_host` | unset | Gitea/Forgejo SSH hostname: skip if you only push to GitHub |
 | `[forge.gitea] api` | unset | `https://<gitea host>/api/v1`: skip if you only push to GitHub |

docs/development.md

@@ -17,7 +17,7 @@ run them.
 | `docker/ulogd.conf` | `ulogd2` config: turns `init-firewall.sh`'s NFLOG-tagged packets into JSON |
 | `docker/log-shipper.sh` | Tails the dnsmasq/ulogd2 logs and ships them to the configured Loki endpoint (`[logging] loki_url`); also ships session transcripts when conversation logging (`[logging] conversation`) is on |
 | `docker/entrypoint.sh` | Runs as root: DNS proxy, firewall, logging, drops to the sandbox user via `gosu`, then execs the session's command |
-| `docker/claude-wrapper.sh` | Shadows `claude` on `PATH` to always add `--dangerously-skip-permissions` |
+| `docker/harness-wrapper.sh` | Shadows the selected harness's command on `PATH` to add its no-confirm flags and dejima's settings layer. Named by no harness; `entrypoint.sh` links it into place |
 | `docker/docker-compose.yml` | Wires up mounts/env; invoked via `bin/dejima`, not directly |
 | `hooks/sandbox-context.sh` | `SessionStart` hook: injects sandbox context/workflow reminders, and any `.dejima.md` the project ships |
 | `.dejima.md` | Project-level agent instructions, harness-agnostic: `CLAUDE.md`'s role under a neutral name. dejima loads a project's into the session context; this one is dejima's own |
@@ -35,6 +35,8 @@ run them.
 | `bin/dejima-project` | Review and approve project domains and dependencies from the host |
 | `bin/dejima-project-lib.sh` | Shared library sourced by `bin/dejima-dep`, `bin/dejima-project`, `bin/dejima` and the remote-access scripts; not on PATH |
 | `bin/dejima-epitaph` | Host-side: keeps the summary a session leaves when its context is compacted away, in a store nothing mounts. Run from `bin/dejima`'s exit trap |
+| `bin/dejima-harness-lib.sh` | Loads the selected harness's plugin and provides the `emit_*` functions it declares through; the guarded-store refusal runs in `emit_mount`. Not on PATH |
+| `bin/harness/<name>.sh` | One per supported harness: what dejima does for that harness that no manifest value could state. Trusted computing base, sourced by `bin/dejima` |
 | `bin/dejima-slug-lib.sh` | The `~/.claude/projects` slug scheme and which slugs belong to a workspace; sourced by `bin/dejima` (what to mount) and `bin/dejima-epitaph` (whose transcripts to keep), so the two cannot disagree. Not on PATH |
 | `bin/dejima-ttyd` | Launches `ttyd` on loopback in front of `dejima-attach` |
 | `systemd/*.service` | User units for `dejima-ttyd` and `dejima-notify-watch`; ship disabled, installed by hand |
@@ -148,3 +150,208 @@ push to one, `runtime.bats` included. That job needs two things from the
 runner that an ordinary one doesn't (the host's Docker socket and the host
 network namespace), and it checks for both up front rather than failing
 obscurely partway through; the file says why each is needed.
+
+## Adding a new harness
+
+`[core] harness` picks a directory under `harnesses/`, and a harness manifest
+declares four things. Everything else dejima does for Claude Code is written
+against Claude Code, and this is the inventory of it: what a second harness
+has to supply, and where dejima has to stop assuming. Taken from a pass over
+the tree, so each row names the file to change rather than describing a
+sketch.
+
+### What a harness must be able to do
+
+Support is per harness and deliberate. A supported harness gets the same
+depth of integration Claude Code has - the same mounts, the same guards, the
+same audit surfaces - so a harness is not a manifest someone drops in. That
+is only possible if the harness can host what those protections need.
+
+These are the requirements. A harness that fails one of the first five
+cannot be supported, and that is a decision about the harness rather than a
+gap in dejima.
+
+| | Requirement | Why it is load-bearing |
+| --- | --- | --- |
+| **R1** | **Unattended execution.** A documented mode that runs tool calls without confirming each one. | The premise the project rests on. A harness that stops to ask is one an operator sits in front of, and the argument for accepting that mode is that the container makes being unattended survivable. |
+| **R2** | **Tool-call interception.** A supported mechanism to inspect a command before it runs and refuse it, without patching the harness. | The push guard, the merge guard and the dangerous-command denylist all live here. They are guards against an eager agent rather than a boundary against a hostile one, but a harness without them ships three protections short and the operator cannot add them back. |
+| **R3** | **Host-controlled context at session start.** A way to place text into the session's context at start, from a file the operator controls and the session cannot rewrite for the run in progress. | How the briefing and the project's `.dejima.md` arrive. It is also how the agent learns it is sandboxed, which is what makes it ask for a domain instead of working around the firewall. |
+| **R4** | **State dejima can locate or discard.** Per-project state must be computable on the host before launch, so it can be scoped per project - or safely discardable, so it can stay container-local. | #104. A store that is neither computable nor discardable cannot be scoped, and mounting it whole reintroduces cross-project context poisoning. |
+| **R5** | **A withholdable credential.** The model credential must live somewhere dejima can decline to mount, and the harness must accept a substitute: a staged fake, or an environment variable pointed at the host-side proxy. | The credential never entering the container is a headline property, not a nicety. |
+
+Three more are required, but may be declared absent in the manifest, in
+which case dejima says at launch what is not in force:
+
+| | Requirement | What is lost without it |
+| --- | --- | --- |
+| **D1** | Session lifecycle signals - something that fires when the agent wants attention and when it stops. | Remote access notifications. The session still runs and is still attachable. |
+| **D2** | A parseable record of the session. | Epitaph, and conversation logging. |
+| **D3** | An enumerable config directory whose extension points can be mounted read-only. | Config parity, and the read-only mounts that stop a session installing a persistent hook for the next one. |
+
+Declaring one absent is a real decision with a visible cost, not a
+formality. It is there so a harness can be supported honestly at a smaller
+guard set rather than shipped with three protections quietly missing.
+
+**The guard rails are declared in the manifest and reported at launch.**
+`guards` lists which of `bash-deny`, `push-guard`, `merge-guard` and
+`notify` the harness can host. A name outside that set is refused, because a
+typo would otherwise turn a guard off in silence. The ones a harness does
+not declare are named once at launch, with what each costs - and nothing is
+printed at all when it hosts them all, so the message stays a signal rather
+than a line to scroll past.
+
+Core gates the work on the declaration rather than on whether a plugin
+happens to define the hook: a harness that forgot to declare a guard but
+implemented it would otherwise get a protection the launch message has just
+told the operator it does not have.
+
+### Worked example: why aider is not supported
+
+aider clears R1 (`--yes-always`), R3 (`--read` places a file in context),
+R4 (its state is `.aider.*` inside the workspace, which is already mounted)
+and R5 (it takes an API key from the environment).
+
+It fails **R2**. aider has no hook or event system; the only occurrence of
+"hook" in its options is `--no-verify`, which controls git's own pre-commit
+hooks. There is no supported point at which a command can be inspected and
+refused, so `git-push-guard.sh`, `merge-guard.sh` and
+`deny-dangerous-bash.sh` have nowhere to live and no equivalent to be
+rebuilt from. It also fails D1.
+
+The container would still bound an aider session. But three guards an
+operator gets everywhere else would be missing with no way to restore them,
+and "supported" would mean something different for that one harness than
+for every other. So it is not supported, and this is the reason.
+
+### Where a harness's support lives: three tiers
+
+| Tier | What | Rule |
+| --- | --- | --- |
+| **Core** | the mechanism, and every enforcement point | harness-agnostic, always |
+| **Manifest** | `harnesses/<name>/harness.conf` | data. Never sourced, never executed. Selects among named core mechanisms and supplies paths |
+| **Plugin** | `bin/harness/<name>.sh` | the harness-specific remainder, as code, in this repository |
+
+**A feature belongs in the manifest if it can be stated as a value.** It only
+moves to a plugin when it cannot. `projects_dir` and `file_history_dir` are
+both paths, so both are manifest keys; the rule that a *name* in the first
+selects an *entry* in the second is Claude Code's own and could not be
+written as a value, so that is the plugin. "Add a manifest key" is the
+answer until it demonstrably is not.
+
+**Plugins live under `bin/`, not beside the manifest.** `dejima-audit`'s
+`tcb_snapshot` covers `install.sh`, `bin/`, `hooks/`, `docker/` and `test/`,
+and not the provider directories. Host-side plugin code under `harnesses/`
+would be code that runs on the host and that a session could edit in
+dejima's own checkout without raising a CRITICAL - the exact class the audit
+exists to catch. Under `bin/` it is covered for free, and "manifests are
+data, never executed" stays true word for word.
+
+**Plugins are sourced, not invoked**, and are part of the trusted computing
+base. The risk worth designing against is not a careless plugin but three
+plugins implementing the security model three ways, so a plugin uses core's
+own primitives rather than re-deriving them. An invoked protocol would also
+put a new text parser on the launch path, and every parsing bug this
+repository has had is in that family.
+
+**The manifest may carry values that are only used as paths or compared as
+data. It must not carry text that becomes part of a parser's grammar, or the
+identity of a security surface.** `dejima-audit`'s `ack` recovers a finding's
+id by stripping a fixed label from the front of the finding text, anchored
+deliberately (#45). Those labels are grammar. Provider directories are not in
+`tcb_snapshot`'s list, so in the self-mount case a session can edit a
+manifest without raising a CRITICAL - which is why host-execution surfaces
+are a plugin hook (`harness_host_exec_surfaces`) rather than a manifest key.
+The label stays a literal in code the audit watches; it just lives with the
+harness that owns it.
+
+**A plugin computes; core enforces.** A plugin declares through `emit_mount`
+and `emit_env`, which validate at the point of declaration - `emit_mount`
+runs the guarded-store refusal there, so a harness state directory that
+overlapped the approval, audit or epitaph store is refused without each
+plugin having to remember. A plugin never touches `extra_mounts` itself, and
+a static test holds that. A plugin may *classify* an audit path; it may never
+suppress a finding.
+
+Every shipped harness has both a manifest and a plugin - a static test
+refuses one without the other, because a manifest alone would present as a
+supported harness while none of the work had been done.
+
+### What the manifest already covers
+
+`harnesses/<name>/harness.conf`, and the full contract is in
+[providers.md](providers.md):
+
+| Key | What it decides |
+| --- | --- |
+| `command` | the container's main process |
+| `keys` | this harness's own `[harness.<name>]` config schema |
+| `resume_command` | what the briefing tells a session to hand the operator |
+| `briefing` | this harness's fragment of the session briefing |
+
+### Reading a harness's own config
+
+`harness_config_get <key>` resolves whichever harness `[core] harness`
+names. Use it; do not spell a `[harness.<name>]` section out at a call site.
+
+`keys` is declared per harness, so a literal section name makes it a
+declaration only one harness can ever be read through - a second harness
+gets selected, gets validated, and is then handed the first one's paths with
+nothing erroring anywhere. Three call sites did exactly that, in
+`bin/dejima-audit` (twice) and `bin/dejima-epitaph`. A static test now holds
+the rule.
+
+It returns empty when no harness is selected. `bin/dejima` refuses to start
+in that state, so that is reachable only from the standalone tools, where a
+harness-specific path resolving to nothing is the honest answer.
+
+### The inventory
+
+| Area | What is Claude Code specific | Where |
+| --- | --- | --- |
+| Install | `npm install -g @anthropic-ai/claude-code`, and a pinned `CLAUDE_CODE_VERSION` build arg | `docker/Dockerfile` |
+| Permission bypass | the flag itself, now `no_confirm_args` in the manifest; the wrapper is generic | `harnesses/<name>/harness.conf` |
+| Settings layering | that overrides arrive as an extra layer rather than a mount over the operator's file (#47) is core; the flag that carries them is `settings_args` in the manifest | `harnesses/<name>/harness.conf` |
+| Telemetry | `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1` | `docker/Dockerfile` |
+| Egress allowlist | `platform.claude.com` always, `api.anthropic.com` only when no credential proxy is in front of it | `docker/fixed-domains.sh` |
+| Credentials | the whole proxy exists because Claude Code authenticates from `~/.claude/.credentials.json` rather than an env var; the entrypoint seeds a well-formed fake so it has something to read | `bin/dejima-anthropic-proxy`, `docker/anthropic-proxy-forwarder.js`, `docker/entrypoint.sh` |
+| Hook protocol | the event payload arrives on stdin; `SessionStart` returns `hookSpecificOutput.hookEventName`/`additionalContext` as JSON, while a `PreToolUse` hook blocks by exiting 2 with its reason on stderr | `hooks/*.sh` |
+| Hook registration | four hooks written into `~/.claude/settings.json` in Claude Code's schema, one `SessionStart` with a `startup\|resume\|clear\|compact` matcher and three `PreToolUse` matching `Bash`. Now in the plugin, gated per declared guard | `bin/harness/claude-code.sh` |
+| Briefing delivery | the briefing and the project's `.dejima.md` reach the session *through* the `SessionStart` hook. No hooks, no briefing | `hooks/sandbox-context.sh` |
+| Notifications | `Notification`/`Stop` hooks, registered per session into the settings layer, are what drop the markers remote access watches | `hooks/dejima-notify.sh`, `bin/dejima` |
+| Config parity | every `~/.claude` subdirectory is enumerated and mounted by name: `plugins`, `hooks`, `skills`, `commands`, `agents`, `output-styles` read-only; `backups`, `tasks`, `plans`, `sessions` read-write | `docker/docker-compose.yml` |
+| Staged config | `settings.json`, `CLAUDE.md` and `statusline.sh` are staged read-only under `/etc/dejima-claude` and installed into place | `docker/entrypoint.sh`, `bin/dejima` |
+| App state | `~/.claude.json` is copied rather than mounted, because it mixes live state with `mcpServers` config | `bin/dejima` |
+| State layout | the project key - cwd with every non-alphanumeric replaced by `-` - is Claude Code's scheme, and dejima reproduces it in four places | `bin/dejima-slug-lib.sh`, `bin/dejima-project-lib.sh`, `docker/log-shipper.sh` |
+| Per-project scoping | `projects/` is mounted one slug at a time and `file-history/` one session at a time, the second resolved by pairing `projects/<slug>/<id>.jsonl` with `file-history/<id>` (#104). Now in the plugin | `bin/harness/claude-code.sh` |
+| Transcript format | conversation logging transforms Claude Code's JSONL line by line | `docker/log-shipper.sh` |
+| Compaction format | epitaph keys on `isCompactSummary` records and the `compact_boundary` that precedes them | `bin/dejima-epitaph` |
+| Audit surfaces | `.claude/settings.json` is CRITICAL and the rest of `.claude/` is a WARNING, because that is where this harness keeps things that run | `bin/dejima-audit` |
+| Host code execution | `statusline.sh` is audited as its own CRITICAL surface because `settings.json`'s `statusLine.command` runs it **unsandboxed on the host**. Declared by the plugin, since a finding's label is a parser's grammar rather than data | `bin/harness/claude-code.sh` |
+
+### Two things worth deciding early
+
+**What runs on the host when the harness is configured.** `statusLine.command`
+is the one that exists today, and it is not a quirk: a harness that will
+execute an operator-configured command outside the container hands a session
+that writes that file a way onto the host. Find that surface in the new
+harness before supporting it, because it belongs in the audit from the first
+release rather than after someone finds it.
+
+**What the harness keeps, and who else can read it.** The per-project
+scoping of `projects/` and `file-history/` exists because a session that can
+write another project's memory can plant text a later session there reads as
+established background (#104). A new harness's state directory needs the same
+question asked of it, one directory at a time. Anything mounted host-wide
+should be there because it is keyed by session rather than by project, and
+because nothing loads it into a session's context at startup - which is the
+reasoning that leaves `tasks`, `plans`, `sessions` and `backups` mounted
+whole today.
+
+### Testing a new harness
+
+`providers.bats` covers the manifest contract itself and is where a new
+`harness.conf` gets its parsing and validation tests. The suites that assert
+on Claude Code paths by name - `config.bats`, `audit.bats`, `static.bats`,
+`runtime.bats` - are the ones that will need a second set, and a green run
+against the existing harness proves nothing about a new one. Nothing in
+`test/` currently runs a second harness end to end.

docs/providers.md

@@ -211,7 +211,11 @@ A workflow's `briefing.md` is plain Markdown plus two marker forms that
 
 | Key | Type | Default | Meaning |
 | --- | --- | --- | --- |
-| `command` | `identifier` | `claude` | The container's main process for this harness. |
+| `command` | `identifier` | `claude` | The container's main process for this harness, and the name the wrapper shadows on `PATH`. `[core] command` defaults to it. |
+| `command_path` | `?path` | (empty) | Where the real binary lives, behind the shadow. |
+| `guards` | `?list:identifier` | (empty) | Which of dejima's guard rails this harness can host: `bash-deny`, `push-guard`, `merge-guard`, `notify`. A name outside that set is refused rather than treated as an unknown guard, since a typo would otherwise turn a guard off silently. The ones a harness does not declare are named at launch - see "What a harness must be able to do" in [development.md](development.md). |
+| `no_confirm_args` | `?template` | (empty) | The flags that make the harness run without confirming each tool call. Required in practice: dejima refuses to launch a harness that names none, because unattended operation is the premise the container is built on (R1 in [development.md](development.md)). |
+| `settings_args` | `?template` | (empty) | How this harness is told to read dejima's own settings layer, mounted at `/etc/dejima-settings.json`. Empty for a harness that takes its overrides some other way. |
 | `keys` | `?list:keyspec` | (empty) | This harness's own `[harness.<name>]` config schema - same grammar as a forge's `keys`. |
 | `resume_command` | `?template` | (empty) | Prose template (may use `{{session_id}}`) shown at the end of the briefing for resuming this exact session on the host. |
 | `briefing` | `?relpath` | (empty) | This harness's briefing fragment file, relative to its own directory. |
@@ -219,14 +223,22 @@ A workflow's `briefing.md` is plain Markdown plus two marker forms that
 Worked example, `harnesses/claude-code/harness.conf`:
 
 ```
-command        = claude
-keys           = projects_dir:path=~/.claude/projects statusline_path:path=~/.claude/statusline.sh
-resume_command = claude --resume {{session_id}}
-briefing       = briefing.md
+command         = claude
+command_path    = /usr/local/share/npm-global/bin/claude
+guards          = bash-deny push-guard merge-guard notify
+no_confirm_args = --dangerously-skip-permissions
+settings_args   = --settings /etc/dejima-settings.json
+keys            = projects_dir:path=~/.claude/projects file_history_dir:path=~/.claude/file-history statusline_path:path=~/.claude/statusline.sh
+resume_command  = claude --resume {{session_id}}
+briefing        = briefing.md
 ```
 
-Reading it: the container's main process is `claude`; `[harness.claude-code]`
-gets `projects_dir` and `statusline_path`, both `path`-typed with defaults;
+Reading it: the container's main process is `claude`, wrapped on `PATH` in
+front of the real binary at `command_path` so that every invocation - not
+only the one the entrypoint makes - gets `--dangerously-skip-permissions`
+and dejima's settings layer; `[harness.claude-code]`
+gets `projects_dir`, `file_history_dir` and `statusline_path`, all `path`-typed
+with defaults;
 resuming the session on the host is `claude --resume <session id>`, with
 `{{session_id}}` filled in at composition time; and its briefing fragment is
 `briefing.md`.

docs/remote-access.md

@@ -792,7 +792,8 @@ the next one is worth checking.
 2. **Is the hook registered?** The `Notification` and `Stop` entries live in
    the throwaway override layer, not in your real `settings.json`:
    `grep -c dejima-notify /etc/dejima-settings.json` from inside should be 2.
-   That file is passed to Claude Code as `--settings` by `claude-wrapper.sh`;
+   That file is passed to the harness by `harness-wrapper.sh`, as whatever
+   its manifest's `settings_args` names (`--settings` for Claude Code);
    if it is missing entirely, this container was not started by `dejima`.
 3. **Does the marker reach the host?** This is the one to check first: it
    splits the chain cleanly in half. From inside the sandbox:

harnesses/claude-code/harness.conf

@@ -1,4 +1,8 @@
-command        = claude
-keys           = projects_dir:path=~/.claude/projects statusline_path:path=~/.claude/statusline.sh
-resume_command = claude --resume {{session_id}}
-briefing       = briefing.md
+command         = claude
+command_path    = /usr/local/share/npm-global/bin/claude
+guards          = bash-deny push-guard merge-guard notify
+no_confirm_args = --dangerously-skip-permissions
+settings_args   = --settings /etc/dejima-settings.json
+keys            = projects_dir:path=~/.claude/projects file_history_dir:path=~/.claude/file-history statusline_path:path=~/.claude/statusline.sh
+resume_command  = claude --resume {{session_id}}
+briefing        = briefing.md

install.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
-# Idempotent installer for dejima. Symlinks this repo's hooks into
-# ~/.claude/hooks, registers them in ~/.claude/settings.json, and puts
+# Idempotent installer for dejima. Registers the selected harness's guard
+# hooks wherever that harness reads them from, and puts
 # bin/dejima, bin/dejima-allow, bin/dejima-dep, bin/dejima-project,
 # bin/dejima-audit and the opt-in remote-access scripts on PATH. Safe to
 # re-run - every step is a no-op if already done, and every change is
@@ -35,113 +35,6 @@ fi
 echo "Found required tools: docker, docker compose v2, jq, python3"
 echo
 
-mkdir -p "$HOME/.claude/hooks"
-
-link_hook() {
-    local name="$1" src="$SCRIPT_DIR/hooks/$1" dest="$HOME/.claude/hooks/$1"
-    if [ -L "$dest" ] && [ "$(readlink -f "$dest")" = "$(readlink -f "$src")" ]; then
-        echo "Skipping: $name already linked to this repo's copy"
-        return
-    fi
-    if [ -e "$dest" ] || [ -L "$dest" ]; then
-        mkdir -p "$BACKUP_DIR"
-        echo "Moving: existing ~/.claude/hooks/$name to $BACKUP_DIR/$name"
-        mv "$dest" "$BACKUP_DIR/$name"
-    fi
-    echo "Linking: $name ($src -> $dest)"
-    ln -s "$src" "$dest"
-}
-
-link_hook sandbox-context.sh
-link_hook git-push-guard.sh
-link_hook merge-guard.sh
-
-# Symlink from before the gitea-merge-guard.sh -> merge-guard.sh rename
-# points at a hooks/ path that no longer exists. Only remove it if it's
-# actually dangling - the same check the claude-sandbox-* cleanup below
-# uses for bin/, so an operator's own file at this name is left alone.
-old_merge_guard="$HOME/.claude/hooks/gitea-merge-guard.sh"
-if [ -L "$old_merge_guard" ] && [ ! -e "$old_merge_guard" ]; then
-    echo "Removing: dangling pre-rename symlink $old_merge_guard"
-    rm -f "$old_merge_guard"
-fi
-
-# Linked so it exists at a stable path for the read-only ~/.claude/hooks
-# mount, but deliberately NOT passed to register_hook below: bin/dejima
-# registers it per session, into a throwaway settings copy, and only when
-# remote access is configured. Registering it here would fire it for every
-# unsandboxed host session too, where it has no marker directory to write to.
-link_hook dejima-notify.sh
-
-# deny-dangerous-bash.sh is a general (non-sandbox-gated) hook that may
-# already be owned by another install (e.g. dotfiles) - only claim it if
-# nothing else already provides it, so this repo works fully standalone
-# without clobbering an existing setup.
-deny_dest="$HOME/.claude/hooks/deny-dangerous-bash.sh"
-if [ -e "$deny_dest" ] || [ -L "$deny_dest" ]; then
-    echo "Skipping: deny-dangerous-bash.sh already present at $deny_dest (leaving it as-is)"
-else
-    echo "Linking: deny-dangerous-bash.sh ($SCRIPT_DIR/hooks/deny-dangerous-bash.sh -> $deny_dest)"
-    ln -s "$SCRIPT_DIR/hooks/deny-dangerous-bash.sh" "$deny_dest"
-fi
-echo
-
-SETTINGS="$HOME/.claude/settings.json"
-if [ ! -f "$SETTINGS" ]; then
-    echo "Creating $SETTINGS"
-    echo '{}' > "$SETTINGS"
-fi
-
-# The registration that went with the symlink removed above. Two things
-# depend on it going: Claude Code reports a missing hook command on every
-# session start while it points at a path that no longer exists, and - until
-# the dedupe below stopped matching it - it also stood in for the
-# registration it was renamed from, so `register_hook merge-guard.sh`
-# skipped and the merge guard was registered nowhere at all. Dropped only
-# when the path it names is gone, so an operator's own file at that name
-# keeps its registration, matching the symlink check above.
-if [ ! -e "$old_merge_guard" ] && jq -e --arg s "/gitea-merge-guard.sh" \
-    '[.hooks.PreToolUse[]?.hooks[]?.command // empty] | any(endswith($s))' \
-    "$SETTINGS" >/dev/null 2>&1; then
-    echo "Removing: stale pre-rename gitea-merge-guard.sh registration from $SETTINGS"
-    settings_tmp=$(mktemp)
-    jq --arg s "/gitea-merge-guard.sh" \
-        '.hooks.PreToolUse = ((.hooks.PreToolUse // [])
-            | map(.hooks = ((.hooks // []) | map(select((.command // "") | endswith($s) | not))))
-            | map(select((.hooks | length) > 0)))' \
-        "$SETTINGS" > "$settings_tmp" && mv "$settings_tmp" "$SETTINGS"
-fi
-
-register_hook() {
-    local event="$1" matcher="$2" script_name="$3" description="$4"
-    # endswith on the leading slash, not test(): test() is an unanchored
-    # regex, so a hook whose name merely ends in another's - which is what a
-    # rename like gitea-merge-guard.sh -> merge-guard.sh produces - read as
-    # already registered, and the new hook was silently never added.
-    if jq -e --arg s "/$script_name" \
-        "[.hooks.${event}[]?.hooks[]?.command // empty] | any(endswith(\$s))" \
-        "$SETTINGS" >/dev/null 2>&1; then
-        echo "Skipping: $script_name already registered as a $event hook"
-        return
-    fi
-    echo "Registering $script_name as a $event hook in $SETTINGS ($description)"
-    local tmp
-    tmp=$(mktemp)
-    jq --arg matcher "$matcher" --arg cmd "\$HOME/.claude/hooks/$script_name" \
-        ".hooks.${event} = ((.hooks.${event} // []) + [{\"matcher\": \$matcher, \"hooks\": [{\"type\": \"command\", \"command\": \$cmd}]}])" \
-        "$SETTINGS" > "$tmp" && mv "$tmp" "$SETTINGS"
-}
-
-register_hook SessionStart "startup|resume|clear|compact" sandbox-context.sh \
-    "injects sandbox context on session start"
-register_hook PreToolUse Bash git-push-guard.sh \
-    "blocks pushes outside the allowed host(s)/branches"
-register_hook PreToolUse Bash merge-guard.sh \
-    "blocks the configured forge's merge command inside the sandbox"
-register_hook PreToolUse Bash deny-dangerous-bash.sh \
-    "blocks obviously destructive Bash commands"
-echo
-
 BIN_DIR="$HOME/.local/bin"
 if [[ ":$PATH:" != *":$BIN_DIR:"* ]]; then
     echo "Warning: $BIN_DIR is not on PATH - add it to your shell profile to run 'dejima' by name instead of the full path." >&2
@@ -295,6 +188,32 @@ else
     chmod 600 "$CONFIG_FILE"
 fi
 
+# Guard registration, after the starter config above rather than before it:
+# where dejima's guards go, and in what shape, is the selected harness's
+# business, and on a fresh install that selection is the one just seeded.
+# Registering before reading it would mean writing one harness's config for
+# an operator who has chosen another.
+#
+# Delegated to the harness's plugin, which is also what gates each guard on
+# the harness having declared it (see `guards` in its manifest).
+echo
+source "$SCRIPT_DIR/bin/dejima-harness-lib.sh"
+_harness="$(config_get core harness 2>/dev/null)" || _harness=""
+if [ -z "$_harness" ]; then
+    echo "No [core] harness is set in $CONFIG_FILE, so no guard hooks were"
+    echo "registered. Set one and re-run ./install.sh."
+else
+    DEJIMA_HARNESS_NAME="$_harness"
+    harness_plugin_load "$_harness"
+    if declare -F harness_register_guards >/dev/null 2>&1; then
+        echo "Registering $_harness's guard hooks"
+        harness_register_guards "$SCRIPT_DIR" "$BACKUP_DIR"
+    else
+        echo "Harness '$_harness' installs no guard hooks."
+        echo
+    fi
+fi
+
 if [ -f "$(config_root)/remote.conf" ]; then
     echo
     echo "Note: $(config_root)/remote.conf is no longer read - its keys moved to the"

test/audit.bats

@@ -23,6 +23,8 @@ setup() {
     CONFIG_DIR="$(mktemp -d)"
     export DEJIMA_CONFIG_DIR="$CONFIG_DIR"
     cat > "$CONFIG_DIR/config" <<EOF
+[core]
+harness = claude-code
 [harness.claude-code]
 projects_dir = $PROJDIR
 statusline_path = $DEJIMA_AUDIT_STATUSLINE
@@ -264,6 +266,24 @@ cmp_() { "$AUDIT" compare "$WS" "$STATE" 2>&1; }
     [ "$output" = "" ]
 }
 
+@test "says so when no harness is selected, rather than auditing a narrower surface in silence" {
+    # The statusline path comes from the selected harness, so with none
+    # selected there is nothing to watch and the compensating control for
+    # the symlink gap covers nothing. bin/dejima refuses to start without
+    # [core] harness, so this state means the audit was driven by hand - and
+    # a clean report over a surface that was never examined is worse than a
+    # noisy one.
+    printf '#!/bin/sh\necho original\n' > "$DEJIMA_AUDIT_STATUSLINE"
+    cat > "$CONFIG_DIR/config" <<EOF
+[audit]
+dir = $AUDITDIR
+baselines_dir = $BASEDIR
+EOF
+    run "$AUDIT" snapshot "$WS" "$STATE"
+    [[ "$output" == *"no [core] harness is set"* ]] || { echo "$output"; return 1; }
+    [[ "$output" == *"NOT checked"* ]] || { echo "$output"; return 1; }
+}
+
 @test "flags a plain regular-file statusline.sh replaced with different content" {
     printf '#!/bin/sh\necho original\n' > "$DEJIMA_AUDIT_STATUSLINE"
     snap
@@ -1381,9 +1401,9 @@ key_of() { printf '%s' "$1" | sha256sum | cut -d' ' -f1; }
     snap
     head -1 "$STATE" | grep -q '^### staging /'
     # The existing section ranges are anchored at ### gitconfig and
-    # ### statusline, so putting staging first must leave them untouched.
+    # ### hostexec, so putting staging first must leave them untouched.
     grep -q '^### gitconfig$' "$STATE"
-    grep -q '^### statusline$' "$STATE"
+    grep -q '^### hostexec$' "$STATE"
 }
 
 @test "denylisted surfaces are never staged, not even transiently" {
@@ -1910,3 +1930,43 @@ sidecar() { local r; r="$(find "$AUDITDIR" -name '*.txt' | sort | tail -1)"; r="
     run "$AUDIT" compare "$WS" "$STATE"
     [[ "$output" != *"writable"* ]]
 }
+
+@test "a host-execution finding still records the id existing baselines hold" {
+    # The id is what an approval is stored under. Generalising the mechanism
+    # must not rename it: every baseline an operator already has says
+    # "statusline:statusline.sh", and an id that no longer matches re-fires
+    # a CRITICAL they approved. The namespace and leaf come from the plugin
+    # for exactly this reason - they are the harness's to keep stable.
+    printf '#!/bin/sh\necho original\n' > "$DEJIMA_AUDIT_STATUSLINE"
+    snap
+    printf '#!/bin/sh\necho changed\n' > "$DEJIMA_AUDIT_STATUSLINE"
+    run cmp_
+    [[ "$output" == *"HOST-CODE-EXECUTION"* ]] || { echo "$output"; return 1; }
+    # Approve it, then confirm the baseline line is the historical id.
+    printf 'a\n' | "$AUDIT" ack "$WS" >/dev/null 2>&1 || true
+    run cat "$BASEDIR/$(printf '%s' "$WS" | sed 's/[^a-zA-Z0-9]/-/g')"
+    [[ "$output" == *"safe statusline:statusline.sh "* ]] \
+        || { echo "baseline id changed: $output"; return 1; }
+}
+
+@test "a harness declaring no host-execution surface is watched for none" {
+    # Not every harness runs something on the host from its own config. The
+    # absence must mean nothing is checked, not that the previous harness's
+    # path is.
+    printf '#!/bin/sh\necho original\n' > "$DEJIMA_AUDIT_STATUSLINE"
+    snap
+    cat > "$CONFIG_DIR/config" <<EOF
+[core]
+harness = claude-code
+[harness.claude-code]
+projects_dir = $PROJDIR
+statusline_path =
+[audit]
+dir = $AUDITDIR
+baselines_dir = $BASEDIR
+EOF
+    printf '#!/bin/sh\necho changed\n' > "$DEJIMA_AUDIT_STATUSLINE"
+    run cmp_
+    [[ "$output" != *"HOST-CODE-EXECUTION"* ]] \
+        || { echo "watched a surface the harness declares no path for: $output"; return 1; }
+}

test/config.bats

@@ -1727,3 +1727,144 @@ _epitaph_transcript() {
     run grep -nE 'extra_mounts\+=.*epitaph' "$REPO_ROOT/bin/dejima"
     [ "$status" -ne 0 ] || { echo "$output"; return 1; }
 }
+
+# --- harness plugins ------------------------------------------------------
+
+@test "a harness with a manifest but no plugin is refused" {
+    # Support is per harness and deliberate. A manifest alone would present
+    # as a supported harness while none of what dejima does for a harness
+    # had been written, which is the "thin drop-in manifest" this design
+    # exists to prevent.
+    _rw_setup
+    workspace="$(mktemp -d)"
+    # A provider root of its own, via the DEJIMA_PROVIDER_ROOT test hook,
+    # rather than a directory added to the checkout: a suite that writes into
+    # the repository it is testing leaves litter when it aborts and collides
+    # with a concurrent run.
+    proot="$(mktemp -d)"
+    cp -a "$REPO_ROOT/forges" "$REPO_ROOT/workflows" "$REPO_ROOT/harnesses" "$proot/"
+    mkdir -p "$proot/harnesses/test-no-plugin"
+    printf 'command = true\n' > "$proot/harnesses/test-no-plugin/harness.conf"
+    write_config '[core]' "ssh_key = $RW_KEY" 'forge = none' 'workflow = local-only' \
+                 'harness = test-no-plugin'
+    DEJIMA_PROVIDER_ROOT="$proot" _rw_launch "$workspace"
+    [ "$status" -ne 0 ] || { echo "launched anyway:"; echo "$output"; return 1; }
+    [[ "$output" == *"No harness plugin for 'test-no-plugin'"* ]] || { echo "$output"; return 1; }
+    rm -rf "$workspace" "$proot"
+}
+
+@test "emit_mount refuses a harness state directory that overlaps a guarded store" {
+    # The reason the refusal lives in emit_mount rather than in each plugin.
+    # A harness's state paths are computed from config rather than written
+    # down, so this is exactly the shape that reaches a mount without anyone
+    # having looked at the value - the same blind spot as #15.
+    _rw_setup
+    workspace="$(mktemp -d)"
+    audit_dir="$(mktemp -d)"
+    write_config '[core]' "ssh_key = $RW_KEY" 'forge = none' 'workflow = local-only' \
+                 '[audit]' "dir = $audit_dir" \
+                 '[harness.claude-code]' "projects_dir = $audit_dir/projects"
+    _rw_launch "$workspace"
+    [ "$status" -ne 0 ] || { echo "launched anyway:"; echo "$output"; return 1; }
+    [[ "$output" == *"Refusing harness state mount"* ]] || { echo "$output"; return 1; }
+    rm -rf "$workspace" "$audit_dir"
+}
+
+@test "a harness that cannot host a guard says so at launch" {
+    # The capability bar allows a harness to be supported at a smaller guard
+    # set. What it does not allow is that being invisible: an operator who
+    # has these everywhere else would otherwise have to read a manifest to
+    # find out they are gone here.
+    _rw_setup
+    workspace="$(mktemp -d)"
+    proot="$(mktemp -d)"
+    cp -a "$REPO_ROOT/forges" "$REPO_ROOT/workflows" "$REPO_ROOT/harnesses" "$proot/"
+    # Same harness, minus two guards, so the message is the only difference.
+    sed -i 's/^guards .*/guards          = bash-deny notify/' \
+        "$proot/harnesses/claude-code/harness.conf"
+    write_config '[core]' "ssh_key = $RW_KEY" 'forge = none' 'workflow = local-only'
+    DEJIMA_PROVIDER_ROOT="$proot" _rw_launch "$workspace"
+    [[ "$output" == *"does not support 2 of dejima's guards"* ]] || { echo "$output"; return 1; }
+    [[ "$output" == *"push-guard"* ]] || { echo "$output"; return 1; }
+    [[ "$output" == *"merge the agent"* || "$output" == *"merge its own pull requests"* ]] \
+        || { echo "$output"; return 1; }
+    rm -rf "$workspace" "$proot"
+}
+
+@test "a harness hosting every guard says nothing about guards" {
+    # The message must not become a line an operator learns to scroll past.
+    _rw_setup
+    workspace="$(mktemp -d)"
+    write_config '[core]' "ssh_key = $RW_KEY" 'forge = none' 'workflow = local-only'
+    _rw_launch "$workspace"
+    [[ "$output" != *"guards"* ]] || { echo "$output"; return 1; }
+    rm -rf "$workspace"
+}
+
+@test "a harness declaring a guard dejima does not know is refused" {
+    # A typo would otherwise turn a guard off silently, which is the failure
+    # the declaration exists to prevent.
+    _rw_setup
+    workspace="$(mktemp -d)"
+    proot="$(mktemp -d)"
+    cp -a "$REPO_ROOT/forges" "$REPO_ROOT/workflows" "$REPO_ROOT/harnesses" "$proot/"
+    sed -i 's/^guards .*/guards          = bash-deny push-gaurd/' \
+        "$proot/harnesses/claude-code/harness.conf"
+    write_config '[core]' "ssh_key = $RW_KEY" 'forge = none' 'workflow = local-only'
+    DEJIMA_PROVIDER_ROOT="$proot" _rw_launch "$workspace"
+    [ "$status" -ne 0 ] || { echo "launched anyway:"; echo "$output"; return 1; }
+    [[ "$output" == *"unknown guard: push-gaurd"* ]] || { echo "$output"; return 1; }
+    rm -rf "$workspace" "$proot"
+}
+
+@test "install.sh registers the selected harness's guards, gated on its declarations" {
+    # Which guards exist and how they are installed is the harness's, so a
+    # harness declaring fewer gets fewer - and dejima does not write a
+    # config belonging to a harness the operator did not choose.
+    local proot; proot="$(mktemp -d)"
+    cp -a "$REPO_ROOT/forges" "$REPO_ROOT/workflows" "$REPO_ROOT/harnesses" "$proot/"
+    sed -i 's/^guards .*/guards          = bash-deny/' \
+        "$proot/harnesses/claude-code/harness.conf"
+    run_install DEJIMA_PROVIDER_ROOT="$proot"
+    [ "$status" -eq 0 ] || { echo "$output"; return 1; }
+    run jq -r '[.hooks.PreToolUse[]?.hooks[]?.command] | join(" ")' \
+        "$CONFIG_DIR/.claude/settings.json"
+    [[ "$output" == *"deny-dangerous-bash.sh"* ]] || { echo "$output"; return 1; }
+    [[ "$output" != *"git-push-guard.sh"* ]] \
+        || { echo "registered an undeclared guard: $output"; return 1; }
+    [[ "$output" != *"merge-guard.sh"* ]] \
+        || { echo "registered an undeclared guard: $output"; return 1; }
+    rm -rf "$proot"
+}
+
+@test "install.sh registers every guard when the harness declares them all" {
+    # The shipped harness, unmodified: the behaviour this replaced, kept.
+    run_install
+    [ "$status" -eq 0 ] || { echo "$output"; return 1; }
+    local cmds
+    cmds="$(jq -r '[.hooks.PreToolUse[]?.hooks[]?.command,
+                    .hooks.SessionStart[]?.hooks[]?.command] | join(" ")' \
+        "$CONFIG_DIR/.claude/settings.json")"
+    local h
+    for h in sandbox-context.sh git-push-guard.sh merge-guard.sh deny-dangerous-bash.sh; do
+        [[ "$cmds" == *"$h"* ]] || { echo "$h not registered: $cmds"; return 1; }
+    done
+    # Linked for the read-only hooks mount, but registered per session by
+    # bin/dejima rather than here, where it would fire for host sessions too.
+    [ -L "$CONFIG_DIR/.claude/hooks/dejima-notify.sh" ]
+    [[ "$cmds" != *"dejima-notify.sh"* ]] \
+        || { echo "notify registered host-wide: $cmds"; return 1; }
+}
+
+@test "install.sh registers no guards when no harness is selected" {
+    # Writing one harness's config for an operator who has chosen another,
+    # or none, is the coupling this removed.
+    # A config that already exists is never overwritten, so this is how an
+    # operator upgrading from before [core] harness was required arrives.
+    printf '[core]\nforge = none\nworkflow = local-only\n' > "$CONFIG_DIR/config"
+    run_install
+    [ "$status" -eq 0 ] || { echo "$output"; return 1; }
+    [[ "$output" == *"No [core] harness is set"* ]] || { echo "$output"; return 1; }
+    [ ! -f "$CONFIG_DIR/.claude/settings.json" ] \
+        || { echo "wrote a harness config anyway"; return 1; }
+}

test/remote.bats

@@ -2498,14 +2498,17 @@ nginx_blocks() {
 }
 
 @test "install.sh links the remote scripts and the notify hook, registers neither, and enables nothing" {
-    grep -q '^link_hook dejima-notify.sh$' "$REPO_ROOT/install.sh"
+    # The hook is linked by the harness plugin now - which file it is, and
+    # where the harness reads it from, is the harness's business - while the
+    # CLIs stay install.sh's, being dejima's own.
+    grep -q '_link_hook dejima-notify.sh' "$REPO_ROOT/bin/harness/claude-code.sh"
     grep -q '^link_bin dejima-attach$' "$REPO_ROOT/install.sh"
     grep -q '^link_bin dejima-ttyd$' "$REPO_ROOT/install.sh"
     grep -q '^link_bin dejima-notify-watch$' "$REPO_ROOT/install.sh"
     # The notify hook is registered per session by bin/dejima, into a
     # throwaway settings copy. Registered here it would fire for every
     # unsandboxed host session too.
-    run grep -nE 'register_hook.*dejima-notify' "$REPO_ROOT/install.sh"
+    run grep -nE '_register .*dejima-notify' "$REPO_ROOT/bin/harness/claude-code.sh"
     [ "$status" -ne 0 ]
     # Standing up a front door is an explicit operator decision. Nothing in
     # the installer may start, enable or even copy a unit. Code only - the

test/static.bats

@@ -482,10 +482,15 @@ EOF
     }
 }
 
-@test "bin/dejima mounts ~/.claude/projects one slug at a time" {
-    grep -q 'workspace_slugs_sorted "$WORKSPACE_DIR"' "$REPO_ROOT/bin/dejima"
-    grep -q 'extra_mounts+=(-v "$HOME/.claude/projects/$_slug:$HOME/.claude/projects/$_slug")' \
-        "$REPO_ROOT/bin/dejima"
+@test "the claude-code plugin mounts projects/ one slug at a time" {
+    # Moved out of bin/dejima into the harness plugin: which directories a
+    # harness keeps, and what decides an entry belongs to this workspace, is
+    # a fact about the harness. The property is unchanged - the tree is
+    # every project's transcripts and memory, and memory is read into
+    # context at session start (#104).
+    local p="$REPO_ROOT/bin/harness/claude-code.sh"
+    grep -q 'workspace_slugs_sorted "$ws"' "$p"
+    grep -q 'emit_mount "$projects/$slug"' "$p"
 }
 
 # Docker creates the parents of a mount point root-owned when they do not
@@ -510,10 +515,10 @@ EOF
     }
 }
 
-@test "bin/dejima mounts ~/.claude/file-history one session at a time" {
-    grep -q 'workspace_session_ids "$HOME/.claude/projects" "$WORKSPACE_DIR"' "$REPO_ROOT/bin/dejima"
-    grep -q 'extra_mounts+=(-v "$HOME/.claude/file-history/$_sid:$HOME/.claude/file-history/$_sid")' \
-        "$REPO_ROOT/bin/dejima"
+@test "the claude-code plugin mounts file-history one session at a time" {
+    local p="$REPO_ROOT/bin/harness/claude-code.sh"
+    grep -q 'workspace_session_ids "$projects" "$ws"' "$p"
+    grep -q 'emit_mount "$history/$sid"' "$p"
 }
 
 @test "the image pre-creates ~/.claude/file-history so the session mounts have a writable parent" {
@@ -694,8 +699,13 @@ EOF
     # Which only takes effect if the flag is actually passed. It goes in the
     # wrapper rather than the entrypoint so it also covers invocations the
     # entrypoint never sees (an interactive shell, claudecode.nvim).
-    grep -qE -- '--settings /etc/dejima-settings\.json' "$SANDBOX_DIR/claude-wrapper.sh"
-    grep -qE -- '"\$\{settings\[@\]\}"' "$SANDBOX_DIR/claude-wrapper.sh"
+    # The flag itself is the harness's now, not the wrapper's: the wrapper
+    # is shared and a --settings it hardcoded would be handed to a harness
+    # that layers settings some other way.
+    grep -qE -- 'settings_args\s*=\s*--settings /etc/dejima-settings\.json' \
+        "$REPO_ROOT/harnesses/claude-code/harness.conf"
+    grep -q 'SANDBOX_HARNESS_SETTINGS' "$SANDBOX_DIR/harness-wrapper.sh"
+    grep -qE -- '\$\{settings\[@\]\+"\$\{settings\[@\]\}"\}' "$SANDBOX_DIR/harness-wrapper.sh"
 }
 
 @test "bin/dejima pre-creates the ~/.claude config files so neither is mounted as a directory" {
@@ -1166,9 +1176,13 @@ cli_payload() { cat "$BATS_TEST_TMPDIR/cli/payload"; }
     [ "$status" -eq 0 ]
 }
 
-@test "install.sh links and registers the merge guard" {
-    grep -qx 'link_hook merge-guard.sh' "$REPO_ROOT/install.sh"
-    grep -q 'register_hook PreToolUse Bash merge-guard.sh' "$REPO_ROOT/install.sh"
+@test "the merge guard is linked and registered" {
+    # In the harness plugin now: which file a guard is and where a harness
+    # reads it from is the harness's, while whether it is installed at all
+    # is gated on the manifest declaring the guard.
+    local p="$REPO_ROOT/bin/harness/claude-code.sh"
+    grep -q 'harness_has_guard merge-guard && _link_hook merge-guard.sh' "$p"
+    grep -q '_register PreToolUse Bash merge-guard.sh' "$p"
 }
 
 # Runs install.sh against a throwaway HOME, with a stub `docker` on PATH so
@@ -1611,9 +1625,12 @@ registered_commands() {
     # coverage (snapshot/compare
     # against real fixtures, including the symlink-swap exploit) lives in
     # test/audit.bats; this just confirms the wiring exists.
-    grep -q 'STATUSLINE_PATH=' "$REPO_ROOT/bin/dejima-audit"
-    grep -q 'statusline_snapshot' "$REPO_ROOT/bin/dejima-audit"
-    grep -q 'HOST-CODE-EXECUTION' "$REPO_ROOT/bin/dejima-audit"
+    # The path and its label are the harness plugin's now; the mechanism
+    # that snapshots and reports them is still the audit's.
+    grep -q 'host_exec_snapshot' "$REPO_ROOT/bin/dejima-audit"
+    grep -q 'host_exec_load' "$REPO_ROOT/bin/dejima-audit"
+    grep -q 'statusline_path' "$REPO_ROOT/bin/harness/claude-code.sh"
+    grep -q 'HOST-CODE-EXECUTION' "$REPO_ROOT/bin/harness/claude-code.sh"
 }
 
 @test "Dockerfile installs the sandbox clipboard fallback into nvim's VIMRUNTIME plugin dir" {
@@ -2042,6 +2059,46 @@ EOF
     done
 }
 
+@test "core never reads a harness's config by a literal harness name" {
+    # `keys` is declared per harness, so a fixed [harness.<name>] at a call
+    # site makes it a declaration only one harness can ever be read through:
+    # a second harness is selected, is validated, and is then handed the
+    # first one's paths with nothing erroring anywhere. A silent wrong
+    # answer, so it gets a test rather than a convention.
+    run grep -rn 'config_get["'"'"' ]*harness\.[a-z]' "$REPO_ROOT/bin"
+    [ "$status" -ne 0 ] || { echo "use harness_config_get instead:"; echo "$output"; return 1; }
+    grep -q '^harness_config_get()' "$REPO_ROOT/bin/dejima-provider-lib.sh"
+}
+
+@test "the harness guide states the bar a harness has to clear" {
+    # Support is per harness and deliberate, at the depth Claude Code has.
+    # That only holds if the requirements are written down: without them
+    # each new harness is argued about rather than measured, and the first
+    # one that cannot host a guard gets waved through.
+    local sec r
+    grep -q '^## Adding a new harness' "$REPO_ROOT/docs/development.md"
+    sec="$(sed -n '/^### What a harness must be able to do/,/^### What the manifest/p' \
+        "$REPO_ROOT/docs/development.md")"
+    [ -n "$sec" ] || { echo "the capability bar is gone"; return 1; }
+    for r in R1 R2 R3 R4 R5; do
+        grep -q "\*\*$r\*\*" <<< "$sec" || { echo "no $r in the bar"; return 1; }
+    done
+    # Unattended execution is the premise every other control is justified
+    # against, so it stays stated rather than assumed.
+    grep -qi 'without confirming each one' <<< "$sec"
+}
+
+@test "a harness dejima declines is declined against a stated requirement" {
+    # The reason has to point at a rule. Otherwise the bar is decoration and
+    # the next harness is decided on how much someone wants it.
+    local sec
+    sec="$(sed -n '/^### Worked example/,/^### What the manifest/p' \
+        "$REPO_ROOT/docs/development.md")"
+    [ -n "$sec" ] || { echo "no worked example of a refusal"; return 1; }
+    grep -q 'R2' <<< "$sec" \
+        || { echo "the refusal names no requirement it failed"; return 1; }
+}
+
 @test "docs/ci.md exists and is linked from the README and docs/security.md" {
     [ -f "$REPO_ROOT/docs/ci.md" ]
     grep -q 'docs/ci\.md' "$REPO_ROOT/README.md"
@@ -2920,3 +2977,192 @@ q
     run grep -n 'scope-flag) form\|scope-flag form' "$REPO_ROOT/README.md"
     [ "$status" -ne 0 ]
 }
+
+# --- harness plugins: a plugin computes, core enforces ---
+
+@test "no harness plugin touches the mount list directly" {
+    # A plugin that appended to extra_mounts itself would skip the
+    # guarded-store refusal emit_mount runs at the point of declaration -
+    # and would skip it differently in each harness, which is how one
+    # security model becomes one per harness. The plugins are trusted code,
+    # so this is held at review time rather than by isolating them.
+    run grep -rn 'extra_mounts' "$REPO_ROOT/bin/harness"
+    [ "$status" -ne 0 ] || { echo "a plugin bypasses emit_mount:"; echo "$output"; return 1; }
+}
+
+@test "a harness plugin defines only hooks core actually calls" {
+    # A function named something core never calls looks wired up and is
+    # dead. Worse, a near-miss of a real hook name (harness_state_mount for
+    # harness_state_mounts) reads as implemented and silently does nothing.
+    local hooks f fn
+    hooks="$(sed -n 's/^DEJIMA_HARNESS_HOOKS="\(.*\)"$/\1/p' \
+        "$REPO_ROOT/bin/dejima-harness-lib.sh")"
+    [ -n "$hooks" ] || { echo "the hook list is gone"; return 1; }
+    for f in "$REPO_ROOT"/bin/harness/*.sh; do
+        [ -f "$f" ] || continue
+        while IFS= read -r fn; do
+            [ -n "$fn" ] || continue
+            case " $hooks " in
+                *" $fn "*) ;;
+                *) echo "$(basename "$f") defines $fn, which core never calls"; return 1 ;;
+            esac
+        done < <(grep -oE '^[a-zA-Z_][a-zA-Z0-9_]*\(\)' "$f" | sed 's/()$//')
+    done
+}
+
+@test "every shipped harness has both a manifest and a plugin" {
+    # Support is per harness and deliberate. A manifest with no plugin is a
+    # half-finished integration that would present as a supported harness.
+    local d name
+    for d in "$REPO_ROOT"/harnesses/*/; do
+        [ -d "$d" ] || continue
+        name="$(basename "$d")"
+        [ -f "$d/harness.conf" ] || { echo "$name has no manifest"; return 1; }
+        [ -f "$REPO_ROOT/bin/harness/$name.sh" ] \
+            || { echo "$name has a manifest but no plugin"; return 1; }
+    done
+    for d in "$REPO_ROOT"/bin/harness/*.sh; do
+        [ -f "$d" ] || continue
+        name="$(basename "$d" .sh)"
+        [ -f "$REPO_ROOT/harnesses/$name/harness.conf" ] \
+            || { echo "$name has a plugin but no manifest"; return 1; }
+    done
+}
+
+@test "harness plugins are inside the trusted computing base the audit watches" {
+    # They run on the host, in the launch path. Under harnesses/ they would
+    # be host-executed code a session could edit in dejima's own checkout
+    # without raising a CRITICAL, because tcb_snapshot covers install.sh,
+    # bin/, hooks/, docker/ and test/ - and not the provider directories.
+    [ -d "$REPO_ROOT/bin/harness" ] || { echo "plugins are not under bin/"; return 1; }
+    run grep -rn 'harness_state_mounts\|harness_plugin_load' "$REPO_ROOT/harnesses"
+    [ "$status" -ne 0 ] || { echo "plugin code under harnesses/:"; echo "$output"; return 1; }
+    sed -n '/^tcb_snapshot()/,/^}/p' "$REPO_ROOT/bin/dejima-audit" | grep -q 'for dir in bin '
+}
+
+# --- the wrapper is the harness's, not Claude Code's ---
+
+@test "the wrapper names no harness, and the image installs it under a neutral name" {
+    # It is shadowed into place under the harness's own command by
+    # entrypoint.sh, because the image is shared across harnesses and the
+    # selection is per launch. A COPY to a fixed name would bake one
+    # harness's command into every image.
+    local w="$SANDBOX_DIR/harness-wrapper.sh"
+    [ -f "$w" ] || { echo "the generic wrapper is gone"; return 1; }
+    run grep -niE 'claude|anthropic' "$w"
+    [ "$status" -ne 0 ] || { echo "the shared wrapper names a harness:"; echo "$output"; return 1; }
+    grep -q 'COPY docker/harness-wrapper.sh /usr/local/bin/dejima-harness-wrapper' \
+        "$SANDBOX_DIR/Dockerfile"
+    run grep -n 'COPY docker/claude-wrapper' "$SANDBOX_DIR/Dockerfile"
+    [ "$status" -ne 0 ] || { echo "the old fixed-name copy is back"; return 1; }
+}
+
+@test "the entrypoint refuses a harness command name that is not a bare name" {
+    # It becomes a path under /usr/local/bin. A value with a slash would
+    # write the symlink somewhere else entirely, and this one arrives from
+    # the host as an environment variable.
+    sed -n '/SANDBOX_HARNESS_COMMAND:-/,/^fi/p' "$SANDBOX_DIR/entrypoint.sh" \
+        | grep -q '\*/\*'
+}
+
+@test "the no-confirm flags come from the harness manifest" {
+    # R1 of the capability bar. The flag was hardcoded in the wrapper, which
+    # made unattended operation a property of the image rather than of the
+    # selected harness.
+    grep -qE -- 'no_confirm_args\s*=\s*--dangerously-skip-permissions' \
+        "$REPO_ROOT/harnesses/claude-code/harness.conf"
+    grep -q 'no_confirm_args' "$REPO_ROOT/bin/dejima"
+    # And a harness that names none is refused rather than run asking for
+    # confirmation on every tool call, which presents as a hang.
+    grep -q 'declares no no_confirm_args' "$REPO_ROOT/bin/dejima"
+}
+
+@test "core's schema holds no harness's command as a default" {
+    # [core] command defaulted to the literal `claude`, so core carried one
+    # harness's command name while the manifest's own `command` key was read
+    # by nothing.
+    run grep -nE '^core\.command\s+identifier\s+claude' "$REPO_ROOT/bin/dejima-config-lib.sh"
+    [ "$status" -ne 0 ] || { echo "core still defaults to a harness command"; return 1; }
+    grep -qE '^core\.command\s+\?identifier' "$REPO_ROOT/bin/dejima-config-lib.sh"
+    grep -q 'SANDBOX_CMD="$SANDBOX_HARNESS_COMMAND"' "$REPO_ROOT/bin/dejima"
+}
+
+# --- guards are declared, not assumed ---
+
+@test "every shipped harness declares which guards it can host" {
+    # An absent `guards` reads as "hosts none", which for a harness that
+    # hosts all four would tell the operator at every launch that four
+    # protections are missing. Silence is not a valid declaration here.
+    local d name g known
+    known="$(sed -n 's/^DEJIMA_KNOWN_GUARDS="\(.*\)"$/\1/p' "$REPO_ROOT/bin/dejima-provider-lib.sh")"
+    [ -n "$known" ] || { echo "the known-guard set is gone"; return 1; }
+    for d in "$REPO_ROOT"/harnesses/*/; do
+        [ -f "$d/harness.conf" ] || continue
+        name="$(basename "$d")"
+        grep -qE '^\s*guards\s*=' "$d/harness.conf" \
+            || { echo "$name declares no guards"; return 1; }
+        for g in $(sed -n 's/^\s*guards\s*=\s*//p' "$d/harness.conf"); do
+            case " $known " in
+                *" $g "*) ;;
+                *) echo "$name declares unknown guard: $g"; return 1 ;;
+            esac
+        done
+    done
+}
+
+@test "the guard set core knows lives with the validation that rejects a name" {
+    # It was in dejima-harness-lib.sh while provider_validate_selection read
+    # it from dejima-provider-lib.sh, so a caller loading only the latter -
+    # providers.bats does - validated against an empty set and rejected
+    # every guard there is.
+    grep -q '^DEJIMA_KNOWN_GUARDS=' "$REPO_ROOT/bin/dejima-provider-lib.sh"
+    run grep -n '^DEJIMA_KNOWN_GUARDS=' "$REPO_ROOT/bin/dejima-harness-lib.sh"
+    [ "$status" -ne 0 ] || { echo "the set is defined in two places"; return 1; }
+}
+
+@test "core gates guard work on the declaration, not on the plugin defining a hook" {
+    # A harness that forgot the declaration but implemented the hook would
+    # get a guard the launch message has just said it does not have.
+    grep -q 'harness_has_guard notify' "$REPO_ROOT/bin/dejima"
+}
+
+@test "install.sh installs no harness's hooks itself" {
+    # Where dejima's guards go, and in what shape, is the selected harness's
+    # business. install.sh knowing ~/.claude/settings.json's schema is the
+    # coupling; it delegates to the harness's plugin now.
+    run grep -nE '\.claude/(settings\.json|hooks)' "$REPO_ROOT/install.sh"
+    [ "$status" -ne 0 ] || { echo "install.sh still writes a harness's config:"; echo "$output"; return 1; }
+    grep -q 'harness_register_guards' "$REPO_ROOT/install.sh"
+    grep -q '^harness_register_guards()' "$REPO_ROOT/bin/harness/claude-code.sh"
+}
+
+@test "the plugin loader does not depend on its caller's SCRIPT_DIR" {
+    # bin/dejima sets it to bin/ and install.sh sets it to the repo root. A
+    # library that resolves paths from one of those only works for one of
+    # its callers.
+    sed -n '/^harness_plugin_load()/,/^}/p' "$REPO_ROOT/bin/dejima-harness-lib.sh" \
+        | grep -q 'BASH_SOURCE'
+    run sed -n '/^harness_plugin_load()/,/^}/p' "$REPO_ROOT/bin/dejima-harness-lib.sh"
+    [[ "$output" != *'$SCRIPT_DIR'* ]] || { echo "$output"; return 1; }
+}
+
+@test "a finding's label lives in trusted code, never in a manifest" {
+    # `ack` recovers an id by stripping a fixed label from the front of a
+    # finding. Those labels are a parser's grammar, and provider directories
+    # are not in tcb_snapshot's list - in the self-mount case a session can
+    # edit a manifest without raising a CRITICAL. So the label stays a
+    # literal in code the audit does watch, which is why host-exec surfaces
+    # are a plugin hook rather than a manifest key.
+    grep -q 'HOST-CODE-EXECUTION' "$REPO_ROOT/bin/harness/claude-code.sh"
+    run grep -rn 'HOST-CODE-EXECUTION' "$REPO_ROOT/harnesses"
+    [ "$status" -ne 0 ] || { echo "a finding label is manifest data:"; echo "$output"; return 1; }
+    run grep -rniE 'host_exec_paths|host_exec_label' "$REPO_ROOT/harnesses" "$REPO_ROOT/bin/dejima-provider-lib.sh"
+    [ "$status" -ne 0 ] || { echo "host-exec surfaces leaked into the manifest schema:"; echo "$output"; return 1; }
+}
+
+@test "the audit resolves host-execution paths from the harness, not a hardcoded one" {
+    run grep -n 'STATUSLINE_PATH' "$REPO_ROOT/bin/dejima-audit"
+    [ "$status" -ne 0 ] || { echo "$output"; return 1; }
+    grep -q 'host_exec_load' "$REPO_ROOT/bin/dejima-audit"
+    grep -q '^harness_host_exec_surfaces()' "$REPO_ROOT/bin/harness/claude-code.sh"
+}