fix(#3795): read the interrupted agent id before clearing the stale marker (#4006)

* test(#3795): the interrupted-agent read must precede the stale-id clear

* fix(#3795): read the interrupted agent id before clearing the stale marker

execute-plan's init_agent_tracking step ran `rm -f
.planning/current-agent-id.txt` BEFORE the existence check that read it,
so the interrupted-agent branch and the Task resume prompt it exists to
offer were unreachable (#3795) — a kill -9 mid-executor left the file,
and the next run deleted it before looking. The read now precedes the
clear; fresh-run semantics (no stale id leaking into the new spawn) are
preserved. A structural guard pins the order.

Emitted-Drift-Ack-Growth: execute-plan.md — #3795: +bytes from reordering the interrupted-agent read before the rm plus the explaining comment

* chore(#3795): changeset fragment (pr number backfilled after PR creation)

* chore(#3795): backfill changeset PR number (4006)

---------

Co-authored-by: sim <sim@local>

.changeset/jolly-yaks-click.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 4006
+---
+**Interrupted executors can be resumed again** — execute-plan deleted `current-agent-id.txt` before the check that read it, so the interrupted-agent detection and its Task `resume` prompt were unreachable after a kill; the id is now captured before the stale marker is cleared. (#3795)

gsd-core/workflows/execute-plan.md

@@ -155,11 +155,14 @@ Fresh context per subagent preserves peak quality. Main context stays lean.
 if [ ! -f .planning/agent-history.json ]; then
   echo '{"version":"1.0","max_entries":50,"entries":[]}' > .planning/agent-history.json
 fi
-rm -f .planning/current-agent-id.txt
+# #3795: read a SURVIVING id before clearing it — the clear used to run
+# first, so the check below was always false and the resume prompt at this
+# step's tail was never offered.
 if [ -f .planning/current-agent-id.txt ]; then
   INTERRUPTED_ID=$(cat .planning/current-agent-id.txt)
   echo "Found interrupted agent: $INTERRUPTED_ID"
 fi
+rm -f .planning/current-agent-id.txt
 ```
 
 If interrupted: ask user to resume (Task `resume` parameter) or start fresh.

tests/execute-plan-interrupted-agent-guard.test.cjs

@@ -0,0 +1,50 @@
+'use strict';
+
+// ─────────────────────────────────────────────────────────────────────────────
+// #3795 — execute-plan's interrupted-agent detection must be REACHABLE.
+//
+// The init_agent_tracking step cleared `.planning/current-agent-id.txt`
+// BEFORE the existence check that read it, so the interrupted-agent branch
+// and the Task `resume` prompt it exists to offer could never execute: a
+// kill -9 mid-executor left the file, and the very next run deleted it
+// before looking. The read must precede the clear.
+// ─────────────────────────────────────────────────────────────────────────────
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const EXECUTE_PLAN_MD = path.join(__dirname, '..', 'gsd-core', 'workflows', 'execute-plan.md');
+
+// execute-plan.md is shipped workflow text — the bytes ARE what the runtime
+// loads; a structural scan over the step's own fenced block tests the
+// deployed contract (same shape as tests/config-get-raw-guard.test.cjs).
+function initAgentTrackingBlock() {
+  const md = fs.readFileSync(EXECUTE_PLAN_MD, 'utf-8');
+  const step = md.indexOf('<step name="init_agent_tracking">');
+  assert.ok(step > 0, 'execute-plan.md must contain the init_agent_tracking step');
+  const end = md.indexOf('</step>', step);
+  assert.ok(end > step, 'init_agent_tracking step must close');
+  return md.slice(step, end);
+}
+
+test('#3795: the interrupted-agent read must precede the stale-id clear', () => {
+  const block = initAgentTrackingBlock();
+  const readCheck = block.indexOf('[ -f .planning/current-agent-id.txt ]');
+  const clear = block.indexOf('rm -f .planning/current-agent-id.txt');
+  assert.ok(readCheck > 0, 'the step must probe for a surviving current-agent-id.txt');
+  assert.ok(clear > 0, 'the step must clear the stale id for the fresh run');
+  assert.ok(
+    readCheck < clear,
+    '#3795: the existence check must run BEFORE the rm — delete-first made the interrupted-agent branch and its Task resume prompt unreachable',
+  );
+  assert.ok(
+    /INTERRUPTED_ID=\$\(/.test(block),
+    'the surviving id must be captured while the file still exists',
+  );
+  assert.ok(
+    /resume/.test(block),
+    'the resume-or-fresh prompt the read enables must stay present',
+  );
+});

tests/no-bare-gsd-tools-command-position.test.cjs

@@ -107,7 +107,7 @@ const PROSE_ALLOWLIST = [
   { file: 'agents/gsd-phase-researcher.md', line: 33, reason: 'package-legitimacy provenance rule names the command as the source of an OK verdict; descriptive' },
   { file: 'agents/gsd-roadmapper.md', line: 642, reason: 'parenthetical "e.g." naming SDK queries a user *could* run; not an agent instruction' },
   { file: 'agents/gsd-intel-updater.md', line: 40, reason: 'cross-platform note names the `gsd-tools intel <subcommand>` CLI surface descriptively ("CLI invocations go through..."); not an agent instruction' },
-  { file: 'gsd-core/workflows/execute-plan.md', line: 416, reason: 'describes the downstream SDK validation step (`validated downstream by ...`); names the mechanism, does not instruct the agent to type it' },
+  { file: 'gsd-core/workflows/execute-plan.md', line: 419, reason: 'describes the downstream SDK validation step (`validated downstream by ...`); names the mechanism, does not instruct the agent to type it' },
 ];
 
 // Resolver-snippet definition lines / probes that must never be flagged. A line