fix(telemetry): one-shot setup events never sweep other sessions' pending markers

gstack-telemetry-log finalizes every .pending-<session> marker that is not
the caller's own as outcome:unknown and deletes it. setup's onboarding
events (_setup_welcome, _setup_playwright) have no session of their own, so
a Chromium bootstrap failure during a live skill session recorded a false
unknown for that session and removed its marker.

New --no-sweep flag skips the stale-marker pass; both setup call sites use
it (the synthetic --session-id did not prevent the sweep). Surfaced by the
Codex adversarial pass.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

bin/gstack-telemetry-log

@@ -10,6 +10,11 @@
 #   gstack-telemetry-log --skill qa --duration 142 --outcome success \
 #     --used-browse true --session-id "12345-1710756600"
 #
+#   --no-sweep  one-shot events with no session of their own (setup's
+#               onboarding events) must not finalize OTHER sessions' in-flight
+#               .pending markers as outcome:unknown — only a skill's own
+#               epilogue may sweep.
+#
 # Env overrides (for testing):
 #   GSTACK_STATE_DIR  — override ~/.gstack state directory
 #   GSTACK_DIR        — override auto-detected gstack root
@@ -48,9 +53,11 @@ SEC_PAYLOAD_HASH=""
 SEC_CONFIDENCE=""
 SEC_LAYER=""
 SEC_VERDICT=""
+NO_SWEEP=""
 
 while [ $# -gt 0 ]; do
   case "$1" in
+    --no-sweep)      NO_SWEEP=1; shift ;;
     --skill)         SKILL="$2"; shift 2 ;;
     --duration)      DURATION="$2"; shift 2 ;;
     --outcome)       OUTCOME="$2"; shift 2 ;;
@@ -93,7 +100,10 @@ fi
 # ─── Finalize stale .pending markers ────────────────────────
 # Each session gets its own .pending-$SESSION_ID file to avoid races
 # between concurrent sessions. Finalize any that don't match our session.
+# --no-sweep (one-shot events from setup) skips this: a marker that is not
+# ours is another live session's, not a stale one.
 for PFILE in "$PENDING_DIR"/.pending-*; do
+  [ -z "$NO_SWEEP" ] || break
   [ -f "$PFILE" ] || continue
   # Skip our own session's marker (it's still in-flight)
   PFILE_BASE="$(basename "$PFILE")"

setup

@@ -2021,7 +2021,7 @@ if [ ! -f "$HOME/.gstack/.welcome-seen" ]; then
   log ""
   # Best-effort onboarding telemetry (respects telemetry!=off; never blocks setup).
   if [ -x "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" ]; then
-    "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" --event-type onboarding --skill _setup_welcome --outcome shown >/dev/null 2>&1 || true
+    "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" --event-type onboarding --skill _setup_welcome --outcome shown --no-sweep >/dev/null 2>&1 || true
   fi
   touch "$HOME/.gstack/.welcome-seen"
 fi
@@ -2641,9 +2641,16 @@ if [ -n "${_PW_FAIL_REASON:-}" ]; then
   case "$_PW_FAIL_REASON" in
     *post-install-launch*) log "  Ubuntu 24.04+ (AppArmor user namespaces): GSTACK_CHROMIUM_NO_SANDBOX=1 ./setup (#2157)" ;;
   esac
-  # Reason code only — never a path or command line — so a support thread can
+  # Reason code only — never a path, hostname, or the installer's output. The
-  # be matched to a code. Telemetry-gated inside gstack-telemetry-log.
+  # event is a one-shot with no session of its own, so --no-sweep keeps it
+  # from finalizing other live sessions' in-flight .pending markers as
+  # outcome:unknown. Telemetry-gated inside gstack-telemetry-log.
   if [ -x "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" ]; then
-    "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" --event-type onboarding --skill _setup_playwright --outcome "$_PW_FAIL_REASON" >/dev/null 2>&1 || true
+    "$SOURCE_GSTACK_DIR/bin/gstack-telemetry-log" --event-type onboarding --skill _setup_playwright --outcome "$_PW_FAIL_REASON" --no-sweep >/dev/null 2>&1 || true
   fi
 fi
+if [ ${#_FOREIGN_SKIPPED_ENTRIES[@]} -gt 0 ]; then
+  log ""
+  log "Not registered (a skill you own already uses the name; left untouched): ${_FOREIGN_SKIPPED_ENTRIES[*]}"
+  log "  Rename or move yours, or switch modes (./setup --prefix / --no-prefix) so the names no longer collide."
+fi

test/telemetry.test.ts

@@ -332,6 +332,20 @@ describe('gstack-telemetry-log', () => {
 });
 
 describe('.pending marker', () => {
+  test('--no-sweep (one-shot setup events) leaves other sessions\' in-flight markers untouched', () => {
+    setConfig('telemetry', 'anonymous');
+    const analyticsDir = path.join(tmpDir, 'analytics');
+    fs.mkdirSync(analyticsDir, { recursive: true });
+    const marker = path.join(analyticsDir, '.pending-live-456');
+    fs.writeFileSync(marker, '{"skill":"ship","ts":"2026-09-04T00:00:00Z","session_id":"live-456","gstack_version":"1.79.0.0"}');
+    run(`${BIN}/gstack-telemetry-log --event-type onboarding --skill _setup_playwright --outcome chromium-install --no-sweep`);
+    expect(fs.existsSync(marker)).toBe(true);
+    const events = parseJsonl();
+    expect(events).toHaveLength(1);
+    expect(events[0].event_type).toBe('onboarding');
+    expect(events[0].outcome).toBe('chromium-install');
+  });
+
   test('finalizes stale .pending from another session as outcome:unknown', () => {
     setConfig('telemetry', 'anonymous');