plasmoid/package/contents/ui/logic.js

@@ -23,6 +23,23 @@ function baseCmd(linkctl, device) {
     return c;
 }
 
+/*
+ * Make a command string unique by appending a shell comment.
+ *
+ * Plasma's executable data engine keys its containers by the command string.
+ * DataEngine::connectSource hands back a pre-existing container and delivers
+ * its *cached* data rather than running the command again; the process only
+ * starts when the container is first created. So re-issuing an identical
+ * command can report success without the camera moving at all, which is
+ * exactly what a stick held at full deflection produces every tick.
+ *
+ * `#` starts a comment in sh, so the trailing counter changes the key the
+ * engine sees without changing what runs.
+ */
+function uniqueify(cmd, seq) {
+    return cmd + " # " + seq;
+}
+
 // Directories searched for the binary, in order. Mirrors the resolver in
 // bin/linkctl-macro. $HOME is left for the shell to expand.
 var SEARCH_DIRS = [

plasmoid/package/contents/ui/main.qml

@@ -31,7 +31,9 @@ PlasmoidItem {
     // a login shell adds to PATH, so a bare name often cannot be run here
     // even when it works in a terminal.
     property string resolvedBin: ""
-    property string probeSource: ""
+    property bool resolving: false
+    // Incremented per command so no two command strings are ever identical.
+    property int seq: 0
     readonly property bool ready: root.resolvedBin !== ""
     readonly property int stepMax: Plasmoid.configuration.maxStep
     readonly property int tickMs: Plasmoid.configuration.tickInterval
@@ -113,8 +115,8 @@ PlasmoidItem {
             return;
         }
         root.statusText = "Looking for linkctl...";
-        root.probeSource = Logic.resolveCommand(root.configuredBin);
-        sh.exec(root.probeSource);
+        root.resolving = true;
+        sh.exec(Logic.resolveCommand(root.configuredBin));
     }
 
     function absorb(stdout) {
@@ -148,8 +150,8 @@ PlasmoidItem {
             disconnectSource(source);
             root.busy = false;
 
-            if (source === root.probeSource) {
-                root.probeSource = "";
+            if (root.resolving) {
+                root.resolving = false;
                 const found = String(out).trim().split("\n")[0].trim();
                 if (found !== "") {
                     root.resolvedBin = found;
@@ -171,7 +173,10 @@ PlasmoidItem {
 
         function exec(cmd) {
             root.busy = true;
-            connectSource(cmd);
+            root.seq += 1;
+            // Never reuse a command string: the engine would serve the
+            // previous run's cached output and not run anything.
+            connectSource(Logic.uniqueify(cmd, root.seq));
         }
     }
 

tests/test_joystick_logic.js

@@ -125,6 +125,21 @@ deep(ctx.absorb('{"pan":1}\nbroken {\n{"tilt":2}'), { pan: 1, tilt: 2 },
      "absorb survives a malformed line between good ones");
 deep(ctx.absorb('Pan: 12.3°'), {}, "absorb ignores human-readable output");
 
+// --- uniqueify ---------------------------------------------------------
+// Plasma's executable engine keys containers by command string and serves a
+// pre-existing container's cached output instead of re-running, so repeating
+// a command verbatim reports success without moving the camera.
+eq(ctx.uniqueify("'linkctl' --force 'center'", 1),
+   "'linkctl' --force 'center' # 1", "uniqueify appends a comment");
+eq(ctx.uniqueify("a", 1) === ctx.uniqueify("a", 2), false,
+   "successive sequence numbers differ");
+// The suffix must be a shell comment so it cannot alter what runs.
+eq(ctx.uniqueify("x", 7).includes(" # "), true, "suffix is a shell comment");
+// A diagonal tick is two chained commands; the suffix must land at the end
+// and so comment out nothing meaningful.
+const tc = ctx.tickCommand(B, 1, 1, 6, false, false);
+eq(ctx.uniqueify(tc, 3), tc + " # 3", "uniqueify appends after a chained command");
+
 // --- resolveCommand ----------------------------------------------------
 // Plasma runs applet commands through `sh -c` with plasmashell's environment,
 // which never sources a login profile. A bare name therefore has to be

tests/test_resolver.sh

@@ -93,5 +93,32 @@ make_exe "$TMP/preferred/linkctl"
 expect "prefers PATH over the search list" "$TMP/both" \
     "$TMP/preferred:/usr/bin:/bin" "$TMP/preferred/linkctl"
 
+# The uniqueness suffix exists only to change the string Plasma keys its
+# command containers by. It must not change what the shell actually runs.
+ask_logic() {
+    node -e '
+const fs = require("fs"), vm = require("vm");
+const src = fs.readFileSync(process.argv[1], "utf8");
+const ctx = { Math, JSON, String };
+vm.createContext(ctx);
+vm.runInContext(src.replace(/^\s*\.pragma\s+library\s*$/m, ""), ctx);
+const tick = ctx.tickCommand(ctx.baseCmd("echo", ""), 1, 1, 6, false, false);
+process.stdout.write(process.argv[2] === "unique"
+    ? ctx.uniqueify(tick, 42) : tick);
+' "$LOGIC" "$1"
+}
+
+checks=$((checks + 1))
+plain_out=$(sh -c "$(ask_logic plain)" 2>&1)
+unique_out=$(sh -c "$(ask_logic unique)" 2>&1)
+if [[ $plain_out == "$unique_out" && -n $plain_out ]]; then
+    printf 'ok   %s\n' "uniqueness suffix does not change what the shell runs"
+else
+    failures=$((failures + 1))
+    printf 'FAIL %s\n       plain:  %s\n       unique: %s\n' \
+        "uniqueness suffix does not change what the shell runs" \
+        "$plain_out" "$unique_out"
+fi
+
 printf '\n%d checks, %d failures\n' "$checks" "$failures"
 [[ $failures -eq 0 ]]