diff --git a/.changeset/proud-geese-caper.md b/.changeset/proud-geese-caper.md
new file mode 100644
index 000000000..d925cf412
--- /dev/null
+++ b/.changeset/proud-geese-caper.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 2227
+---
+**`/gsd-debug` no longer stalls on a phantom background handoff** — the orchestrator treated the foreground session-manager spawn as a background task and queried its agent ID via TaskOutput (which needs a task ID), then waited on a handoff that was never queryable. The workflow now states the spawn is foreground/blocking, forbids passing an agent ID to TaskOutput, and gives a lost-handoff recovery path. (#2196)
diff --git a/gsd-core/workflows/debug.md b/gsd-core/workflows/debug.md
index f3ae29109..7bd7a78d4 100644
--- a/gsd-core/workflows/debug.md
+++ b/gsd-core/workflows/debug.md
@@ -190,6 +190,8 @@ Create `.planning/debug/{slug}.md` with initial state using the Write tool (neve
 
 After initial context setup, spawn the session manager to handle the full checkpoint/continuation loop. The session manager handles specialist_hint dispatch internally: when gsd-debugger returns ROOT CAUSE FOUND it extracts the specialist_hint field and invokes the matching skill (e.g. typescript-expert, swift-concurrency) before offering fix options.
 
+> **Foreground, blocking spawn — #2196.** The `Agent(subagent_type="gsd-debug-session-manager", …)` call below is FOREGROUND and BLOCKING — it returns the compact session summary directly. Wait for it; do not background it, and do not poll for it. Never pass an agent or session identifier to `TaskOutput` — an agent ID is NOT a task ID, so `TaskOutput <agent-id>` always returns `No task found with ID`. If the spawn returns no usable result (the handoff is lost), do NOT claim the session is still running: preserve the checkpoint at `.planning/debug/{slug}.md`, report the failed handoff plainly, and resume by re-spawning the session manager or via `/gsd:debug continue {slug}`.
+
 Print before spawning (runs in a subagent — no output until it returns, ~1–5 min; expected, not a freeze):
 ```
 [debug] Delegating loop to session manager...
diff --git a/tests/fix-2196-debug-agent-handoff.test.cjs b/tests/fix-2196-debug-agent-handoff.test.cjs
new file mode 100644
index 000000000..623533aaf
--- /dev/null
+++ b/tests/fix-2196-debug-agent-handoff.test.cjs
@@ -0,0 +1,52 @@
+'use strict';
+
+/**
+ * #2194… no — #2196: the /gsd-debug orchestrator misused the foreground
+ * session-manager Agent() spawn as a background task, then queried the returned
+ * agent ID via TaskOutput (which expects a task ID) — yielding "No task found
+ * with ID" and leaving the workflow waiting on a handoff that was never
+ * queryable, with no recovery.
+ *
+ * The fix makes debug.md state explicitly that the spawn is foreground/blocking,
+ * that an agent ID must never be passed to TaskOutput, and that a lost handoff
+ * must be recovered (preserve checkpoint + resume). debug.md IS the product the
+ * runtime loads, so this asserts the deployed text carries that contract.
+ */
+
+const { describe, test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const DEBUG_MD = path.join(__dirname, '..', 'gsd-core', 'workflows', 'debug.md');
+
+describe('#2196 debug.md session-manager spawn contract', () => {
+  const content = fs.readFileSync(DEBUG_MD, 'utf-8');
+  const sectionStart = content.indexOf('Session Management');
+  const section = sectionStart !== -1 ? content.slice(sectionStart) : '';
+
+  test('debug.md has the Session Management section', () => {
+    assert.notEqual(sectionStart, -1, 'debug.md must contain the Session Management section');
+  });
+
+  test('the session-manager spawn is declared foreground/blocking (not backgrounded)', () => {
+    assert.ok(/foreground/i.test(section) && /blocking/i.test(section),
+      'the Agent() spawn must be declared foreground and blocking so it is not polled');
+  });
+
+  test('an agent ID must not be passed to TaskOutput', () => {
+    assert.ok(/TaskOutput/.test(section),
+      'the contract must mention TaskOutput by name');
+    assert.ok(/agent ID is NOT a task ID|agent ID is not a task ID/i.test(section),
+      'the contract must state an agent ID is not a task ID');
+  });
+
+  test('a lost handoff has a recovery path (preserve checkpoint + resume)', () => {
+    // Pin the CANONICAL colon form — the retired /gsd-debug hyphen syntax is
+    // rejected by the slash-command-namespace guard, so this must be /gsd:debug.
+    assert.ok(/\/gsd:debug continue \{slug\}/.test(section),
+      'the contract must point to /gsd:debug continue {slug} (canonical colon form) as the resume path');
+    assert.ok(/do not claim|do NOT claim/i.test(section),
+      'the contract must forbid claiming a lost-handoff session is still running');
+  });
+});
diff --git a/tests/fixtures/golden-install-parity/antigravity.json b/tests/fixtures/golden-install-parity/antigravity.json
index 2529f592e..c81c1c0ee 100644
--- a/tests/fixtures/golden-install-parity/antigravity.json
+++ b/tests/fixtures/golden-install-parity/antigravity.json
@@ -211,7 +211,7 @@
   "gsd-core/workflows/code-review-fix.md": "60640e633b0a124b",
   "gsd-core/workflows/code-review.md": "5c40505c01871153",
   "gsd-core/workflows/complete-milestone.md": "aaf272074acec69d",
-  "gsd-core/workflows/debug.md": "68f1ddc74886ebe5",
+  "gsd-core/workflows/debug.md": "af2d1ae03b24fc71",
   "gsd-core/workflows/diagnose-issues.md": "c8c41993c277363c",
   "gsd-core/workflows/discovery-phase.md": "3de990caffdde4f8",
   "gsd-core/workflows/discuss-phase-assumptions.md": "8581fd77def7ce84",
diff --git a/tests/fixtures/golden-install-parity/augment.json b/tests/fixtures/golden-install-parity/augment.json
index 9715eb856..8b4b9e282 100644
--- a/tests/fixtures/golden-install-parity/augment.json
+++ b/tests/fixtures/golden-install-parity/augment.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "2e113d1f4350a075",
   "gsd-core/workflows/code-review.md": "334c90c401f291f8",
   "gsd-core/workflows/complete-milestone.md": "c1f91b77f4ace7f2",
-  "gsd-core/workflows/debug.md": "849d7e5b9c12dcae",
+  "gsd-core/workflows/debug.md": "c581e89aa9d9d71e",
   "gsd-core/workflows/diagnose-issues.md": "6cc3900891dfb927",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "f5b765d33eba4f88",
diff --git a/tests/fixtures/golden-install-parity/claude-local.json b/tests/fixtures/golden-install-parity/claude-local.json
index e825323e6..ec1bd721d 100644
--- a/tests/fixtures/golden-install-parity/claude-local.json
+++ b/tests/fixtures/golden-install-parity/claude-local.json
@@ -281,7 +281,7 @@
   "gsd-core/workflows/code-review-fix.md": "78c716068ccdf820",
   "gsd-core/workflows/code-review.md": "2d21452eb0449fdd",
   "gsd-core/workflows/complete-milestone.md": "9962377cddee50d7",
-  "gsd-core/workflows/debug.md": "3354c726abbfd75b",
+  "gsd-core/workflows/debug.md": "18c97b804f2dd5dd",
   "gsd-core/workflows/diagnose-issues.md": "db6a599674efbc4d",
   "gsd-core/workflows/discovery-phase.md": "a20dfb32adec51de",
   "gsd-core/workflows/discuss-phase-assumptions.md": "35a3b2d1285565d8",
diff --git a/tests/fixtures/golden-install-parity/claude.json b/tests/fixtures/golden-install-parity/claude.json
index 89a1f3e6f..c2f7e3af9 100644
--- a/tests/fixtures/golden-install-parity/claude.json
+++ b/tests/fixtures/golden-install-parity/claude.json
@@ -210,7 +210,7 @@
   "gsd-core/workflows/code-review-fix.md": "722416b71b31c5fc",
   "gsd-core/workflows/code-review.md": "506412604f767adc",
   "gsd-core/workflows/complete-milestone.md": "dcf1182398efb1ca",
-  "gsd-core/workflows/debug.md": "a9397fd35cca2240",
+  "gsd-core/workflows/debug.md": "7183935f8e145a01",
   "gsd-core/workflows/diagnose-issues.md": "75ffc381ac3059ff",
   "gsd-core/workflows/discovery-phase.md": "6161c60d752d0058",
   "gsd-core/workflows/discuss-phase-assumptions.md": "a8cd1db094fefd35",
diff --git a/tests/fixtures/golden-install-parity/cline.json b/tests/fixtures/golden-install-parity/cline.json
index d7f323bbc..2a41dd607 100644
--- a/tests/fixtures/golden-install-parity/cline.json
+++ b/tests/fixtures/golden-install-parity/cline.json
@@ -214,7 +214,7 @@
   "gsd-core/workflows/code-review-fix.md": "e4549af672e74e6f",
   "gsd-core/workflows/code-review.md": "a65e3e869508f89e",
   "gsd-core/workflows/complete-milestone.md": "c0808127038a8f86",
-  "gsd-core/workflows/debug.md": "f42e8e3cbc298694",
+  "gsd-core/workflows/debug.md": "337fc2076e7fc449",
   "gsd-core/workflows/diagnose-issues.md": "e616d0d730328d68",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "9efcb2ef6a9245b3",
diff --git a/tests/fixtures/golden-install-parity/codebuddy.json b/tests/fixtures/golden-install-parity/codebuddy.json
index 3ef9ae7aa..ebccb820a 100644
--- a/tests/fixtures/golden-install-parity/codebuddy.json
+++ b/tests/fixtures/golden-install-parity/codebuddy.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "2e113d1f4350a075",
   "gsd-core/workflows/code-review.md": "334c90c401f291f8",
   "gsd-core/workflows/complete-milestone.md": "c1f91b77f4ace7f2",
-  "gsd-core/workflows/debug.md": "849d7e5b9c12dcae",
+  "gsd-core/workflows/debug.md": "c581e89aa9d9d71e",
   "gsd-core/workflows/diagnose-issues.md": "77d98ac07c4a26ff",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "f5b765d33eba4f88",
diff --git a/tests/fixtures/golden-install-parity/codex.json b/tests/fixtures/golden-install-parity/codex.json
index 15d7132dd..cd6c6ccf2 100644
--- a/tests/fixtures/golden-install-parity/codex.json
+++ b/tests/fixtures/golden-install-parity/codex.json
@@ -317,7 +317,7 @@
   "gsd-core/workflows/code-review-fix.md": "ae7f9c6b39a23c12",
   "gsd-core/workflows/code-review.md": "eadada9e0a89adf2",
   "gsd-core/workflows/complete-milestone.md": "017df7443bd08da5",
-  "gsd-core/workflows/debug.md": "cc7b2d2fd4307a78",
+  "gsd-core/workflows/debug.md": "7c3b407470762585",
   "gsd-core/workflows/diagnose-issues.md": "e38bb21d06dff077",
   "gsd-core/workflows/discovery-phase.md": "71a4b78ff876a854",
   "gsd-core/workflows/discuss-phase-assumptions.md": "0d936ec25299917c",
diff --git a/tests/fixtures/golden-install-parity/copilot.json b/tests/fixtures/golden-install-parity/copilot.json
index 813333959..d24e717ad 100644
--- a/tests/fixtures/golden-install-parity/copilot.json
+++ b/tests/fixtures/golden-install-parity/copilot.json
@@ -212,7 +212,7 @@
   "gsd-core/workflows/code-review-fix.md": "fda53892ae4b17fc",
   "gsd-core/workflows/code-review.md": "f1c045ec4d33abc8",
   "gsd-core/workflows/complete-milestone.md": "470cf39261400ee2",
-  "gsd-core/workflows/debug.md": "36cb536be452d79e",
+  "gsd-core/workflows/debug.md": "505ed67d48b1fa9d",
   "gsd-core/workflows/diagnose-issues.md": "42acbe2a43fc886e",
   "gsd-core/workflows/discovery-phase.md": "8e99da61fb2b7074",
   "gsd-core/workflows/discuss-phase-assumptions.md": "ab0c432b84038681",
diff --git a/tests/fixtures/golden-install-parity/cursor.json b/tests/fixtures/golden-install-parity/cursor.json
index f16b51a78..dd01c479c 100644
--- a/tests/fixtures/golden-install-parity/cursor.json
+++ b/tests/fixtures/golden-install-parity/cursor.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "c57af378033b1b58",
   "gsd-core/workflows/code-review.md": "32c37bcbec8b8698",
   "gsd-core/workflows/complete-milestone.md": "1400a4856f592f3e",
-  "gsd-core/workflows/debug.md": "a73d8018986131ba",
+  "gsd-core/workflows/debug.md": "c02dec84c8a346b9",
   "gsd-core/workflows/diagnose-issues.md": "cd582747131726e3",
   "gsd-core/workflows/discovery-phase.md": "7dcf150998559c11",
   "gsd-core/workflows/discuss-phase-assumptions.md": "c25c6a6c633d71b6",
diff --git a/tests/fixtures/golden-install-parity/hermes.json b/tests/fixtures/golden-install-parity/hermes.json
index 7a187e3b0..57f4fee5d 100644
--- a/tests/fixtures/golden-install-parity/hermes.json
+++ b/tests/fixtures/golden-install-parity/hermes.json
@@ -211,7 +211,7 @@
   "gsd-core/workflows/code-review-fix.md": "e829d3baf9901b54",
   "gsd-core/workflows/code-review.md": "50a05ab8957bd05f",
   "gsd-core/workflows/complete-milestone.md": "f1866541148dc291",
-  "gsd-core/workflows/debug.md": "15cf6999e85dcc8c",
+  "gsd-core/workflows/debug.md": "639348c8657e7147",
   "gsd-core/workflows/diagnose-issues.md": "16f2d2a85335641f",
   "gsd-core/workflows/discovery-phase.md": "6161c60d752d0058",
   "gsd-core/workflows/discuss-phase-assumptions.md": "3a1e215890d2b3f4",
diff --git a/tests/fixtures/golden-install-parity/kilo.json b/tests/fixtures/golden-install-parity/kilo.json
index c363502d4..a2cc18051 100644
--- a/tests/fixtures/golden-install-parity/kilo.json
+++ b/tests/fixtures/golden-install-parity/kilo.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "722416b71b31c5fc",
   "gsd-core/workflows/code-review.md": "506412604f767adc",
   "gsd-core/workflows/complete-milestone.md": "59753bf44d4300da",
-  "gsd-core/workflows/debug.md": "a72d830ac3df74aa",
+  "gsd-core/workflows/debug.md": "28c964bceb6f03af",
   "gsd-core/workflows/diagnose-issues.md": "210b5b313e8a559a",
   "gsd-core/workflows/discovery-phase.md": "ca7b2be46e59e862",
   "gsd-core/workflows/discuss-phase-assumptions.md": "3ef1df313e715387",
diff --git a/tests/fixtures/golden-install-parity/kimi.json b/tests/fixtures/golden-install-parity/kimi.json
index 43ff9373a..eef41d3cd 100644
--- a/tests/fixtures/golden-install-parity/kimi.json
+++ b/tests/fixtures/golden-install-parity/kimi.json
@@ -275,7 +275,7 @@
   "gsd-core/workflows/code-review-fix.md": "2e113d1f4350a075",
   "gsd-core/workflows/code-review.md": "334c90c401f291f8",
   "gsd-core/workflows/complete-milestone.md": "c1f91b77f4ace7f2",
-  "gsd-core/workflows/debug.md": "849d7e5b9c12dcae",
+  "gsd-core/workflows/debug.md": "c581e89aa9d9d71e",
   "gsd-core/workflows/diagnose-issues.md": "67c058fc7ae6026b",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "f5b765d33eba4f88",
diff --git a/tests/fixtures/golden-install-parity/opencode.json b/tests/fixtures/golden-install-parity/opencode.json
index 8cbf839b3..7c19f52c7 100644
--- a/tests/fixtures/golden-install-parity/opencode.json
+++ b/tests/fixtures/golden-install-parity/opencode.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "adb9388bb157610c",
   "gsd-core/workflows/code-review.md": "ae6bcbd1575aeec4",
   "gsd-core/workflows/complete-milestone.md": "614299b2c08e66c3",
-  "gsd-core/workflows/debug.md": "9d4a8afc8d36be93",
+  "gsd-core/workflows/debug.md": "437b47e14eba8786",
   "gsd-core/workflows/diagnose-issues.md": "2971c699d52f1b85",
   "gsd-core/workflows/discovery-phase.md": "724408336596c50c",
   "gsd-core/workflows/discuss-phase-assumptions.md": "92e43cd12200c610",
diff --git a/tests/fixtures/golden-install-parity/pi.json b/tests/fixtures/golden-install-parity/pi.json
index ece2925e8..bcf46ba88 100644
--- a/tests/fixtures/golden-install-parity/pi.json
+++ b/tests/fixtures/golden-install-parity/pi.json
@@ -178,7 +178,7 @@
   "gsd-core/workflows/code-review-fix.md": "2e113d1f4350a075",
   "gsd-core/workflows/code-review.md": "334c90c401f291f8",
   "gsd-core/workflows/complete-milestone.md": "c1f91b77f4ace7f2",
-  "gsd-core/workflows/debug.md": "849d7e5b9c12dcae",
+  "gsd-core/workflows/debug.md": "c581e89aa9d9d71e",
   "gsd-core/workflows/diagnose-issues.md": "d6d978fddfd5da8d",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "f5b765d33eba4f88",
diff --git a/tests/fixtures/golden-install-parity/qwen.json b/tests/fixtures/golden-install-parity/qwen.json
index f1213ed48..81c60c85f 100644
--- a/tests/fixtures/golden-install-parity/qwen.json
+++ b/tests/fixtures/golden-install-parity/qwen.json
@@ -211,7 +211,7 @@
   "gsd-core/workflows/code-review-fix.md": "f3725ae9d685bed2",
   "gsd-core/workflows/code-review.md": "29125604bed2c467",
   "gsd-core/workflows/complete-milestone.md": "40085d32b15805c8",
-  "gsd-core/workflows/debug.md": "c23d067580b09f63",
+  "gsd-core/workflows/debug.md": "a4e4c2f6d004460e",
   "gsd-core/workflows/diagnose-issues.md": "652ae26975f82242",
   "gsd-core/workflows/discovery-phase.md": "6161c60d752d0058",
   "gsd-core/workflows/discuss-phase-assumptions.md": "18712f78bb960ec8",
diff --git a/tests/fixtures/golden-install-parity/trae.json b/tests/fixtures/golden-install-parity/trae.json
index aa3551cf0..027a8b0ac 100644
--- a/tests/fixtures/golden-install-parity/trae.json
+++ b/tests/fixtures/golden-install-parity/trae.json
@@ -211,7 +211,7 @@
   "gsd-core/workflows/code-review-fix.md": "f2761f7f8c4a5674",
   "gsd-core/workflows/code-review.md": "47663a2922756c5e",
   "gsd-core/workflows/complete-milestone.md": "6e918b72bd885426",
-  "gsd-core/workflows/debug.md": "197d3642a6704de5",
+  "gsd-core/workflows/debug.md": "7783c3cb81fef70d",
   "gsd-core/workflows/diagnose-issues.md": "9274b11a3db98c65",
   "gsd-core/workflows/discovery-phase.md": "b32b6197b66c9a13",
   "gsd-core/workflows/discuss-phase-assumptions.md": "e376b1cf29379df4",
diff --git a/tests/fixtures/golden-install-parity/windsurf.json b/tests/fixtures/golden-install-parity/windsurf.json
index 7bec92ba7..76b19cb99 100644
--- a/tests/fixtures/golden-install-parity/windsurf.json
+++ b/tests/fixtures/golden-install-parity/windsurf.json
@@ -211,7 +211,7 @@
   "gsd-core/workflows/code-review-fix.md": "b99b1f20bb27c291",
   "gsd-core/workflows/code-review.md": "faa87faf07ae765a",
   "gsd-core/workflows/complete-milestone.md": "f463bf4e86ac26f6",
-  "gsd-core/workflows/debug.md": "52243eb936a43150",
+  "gsd-core/workflows/debug.md": "d0ee63e547f4d997",
   "gsd-core/workflows/diagnose-issues.md": "447072aa72385271",
   "gsd-core/workflows/discovery-phase.md": "7dcf150998559c11",
   "gsd-core/workflows/discuss-phase-assumptions.md": "b091b3d3e580dd29",
diff --git a/tests/fixtures/golden-install-parity/zcode.json b/tests/fixtures/golden-install-parity/zcode.json
index f9aa16f65..7c3ef7577 100644
--- a/tests/fixtures/golden-install-parity/zcode.json
+++ b/tests/fixtures/golden-install-parity/zcode.json
@@ -282,7 +282,7 @@
   "gsd-core/workflows/code-review-fix.md": "2e113d1f4350a075",
   "gsd-core/workflows/code-review.md": "334c90c401f291f8",
   "gsd-core/workflows/complete-milestone.md": "c1f91b77f4ace7f2",
-  "gsd-core/workflows/debug.md": "849d7e5b9c12dcae",
+  "gsd-core/workflows/debug.md": "c581e89aa9d9d71e",
   "gsd-core/workflows/diagnose-issues.md": "aa8d787db8f3c46c",
   "gsd-core/workflows/discovery-phase.md": "3ba7cfb89fb1e761",
   "gsd-core/workflows/discuss-phase-assumptions.md": "f5b765d33eba4f88",
diff --git a/tests/workflow-size-baseline.json b/tests/workflow-size-baseline.json
index 9e7b9fc87..7ba2a99d9 100644
--- a/tests/workflow-size-baseline.json
+++ b/tests/workflow-size-baseline.json
@@ -14,7 +14,7 @@
   "code-review-fix.md": 24320,
   "code-review.md": 31916,
   "complete-milestone.md": 31071,
-  "debug.md": 13549,
+  "debug.md": 14241,
   "diagnose-issues.md": 12864,
   "discovery-phase.md": 8651,
   "discuss-phase-assumptions.md": 27302,