fix(gateway): enforce [task-id] prefix on every commit

ContentActions.commit was stripping user-supplied prefixes but never
re-adding the canonical one. Dev prompt promised auto-prefix; code
delivered nothing. Now every gateway commit lands with [task-id-short].

Format choice: simple [task_id[:8]] (8-char), matching the dev prompt
("Auto-prefixes [task-id]") and CLAUDE.md's documented commit format.
The legacy templates/git/commit.py uses the richer
[root_short:task_short] for the commit_for_task API path with full
traceability metadata; the gateway commit path is intentionally simpler
and stays aligned with the prompt-level promise.

roboco/services/gateway/content_actions.py

@@ -113,14 +113,18 @@ class ContentActions:
                 remediate="call give_me_work() first",
                 context_briefing={},
             )
+        canonical_prefix = f"[{str(t.id)[:8]}]"
+        final_message = f"{canonical_prefix} {subject}"
         commit_result = await self.git.commit(
             branch_name=t.branch_name,
-            message=subject,
+            message=final_message,
             task_id=t.id,
             files=files,
         )
         sha = commit_result.get("sha", "")
-        await self.task.add_progress(t.id, agent_id, f"committed {sha[:8]}: {subject}")
+        await self.task.add_progress(
+            t.id, agent_id, f"committed {sha[:8]}: {final_message}"
+        )
         return Envelope.ok(
             status=str(t.status),
             task_id=str(t.id),

tests/unit/gateway/test_commit_prefix.py

@@ -0,0 +1,145 @@
+"""Every gateway commit message gets [task-id-short] prefix.
+
+ContentActions.commit promises in the dev prompt that `[task-id]` is
+auto-prefixed onto every commit. The gateway strips any user-supplied
+prefix via `_TASK_ID_PREFIX_RE` but, before this guard, never re-added
+the canonical one. These tests pin the contract.
+"""
+
+from __future__ import annotations
+
+from unittest.mock import AsyncMock, MagicMock
+from uuid import uuid4
+
+import pytest
+from roboco.services.gateway.content_actions import ContentActions, ContentActionsDeps
+
+
+def _make_deps(**overrides: AsyncMock) -> ContentActionsDeps:
+    """Build a ContentActionsDeps for tests; mirrors test_content_actions."""
+    if "task" in overrides:
+        task = overrides["task"]
+    else:
+        task = AsyncMock()
+        task.get_active_task_for_agent.return_value = None
+
+    if "git" in overrides:
+        git = overrides["git"]
+    else:
+        git = AsyncMock()
+        git.commit.return_value = {"sha": "abc12345"}
+        git.diff.return_value = ""
+
+    messaging = overrides.get("messaging", AsyncMock())
+    a2a = overrides.get("a2a", AsyncMock())
+    journal = overrides.get("journal", AsyncMock())
+    workspace = overrides.get("workspace", AsyncMock())
+    return ContentActionsDeps(
+        task=task,
+        git=git,
+        messaging=messaging,
+        a2a=a2a,
+        journal=journal,
+        workspace=workspace,
+    )
+
+
+@pytest.mark.asyncio
+async def test_commit_prefixes_with_task_id_short() -> None:
+    """Plain message gets `[task-id-short] ` prepended."""
+    aid = uuid4()
+    tid = uuid4()
+    expected_prefix = f"[{str(tid)[:8]}]"
+
+    t = MagicMock(
+        id=tid,
+        assigned_to=aid,
+        plan="x",
+        status="in_progress",
+        branch_name="feature/backend/abcd1234",
+    )
+    task_svc = AsyncMock()
+    task_svc.get_active_task_for_agent.return_value = t
+    git_svc = AsyncMock()
+    git_svc.commit.return_value = {"sha": "deadbeef"}
+
+    deps = _make_deps(task=task_svc, git=git_svc)
+    actions = ContentActions(deps)
+
+    await actions.commit(
+        agent_id=aid,
+        message="feat(api): add login endpoint for session bootstrap",
+    )
+
+    git_svc.commit.assert_awaited()
+    # git.commit takes keyword-only args (branch_name, message, task_id, files)
+    msg = git_svc.commit.await_args.kwargs["message"]
+    assert msg.startswith(expected_prefix), (
+        f"expected {expected_prefix} prefix; got {msg!r}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_commit_strips_then_re_adds_prefix() -> None:
+    """If the agent supplied a wrong prefix, strip it and add the canonical one."""
+    aid = uuid4()
+    tid = uuid4()
+    expected_prefix = f"[{str(tid)[:8]}]"
+
+    t = MagicMock(
+        id=tid,
+        assigned_to=aid,
+        plan="x",
+        status="in_progress",
+        branch_name="feature/backend/abcd1234",
+    )
+    task_svc = AsyncMock()
+    task_svc.get_active_task_for_agent.return_value = t
+    git_svc = AsyncMock()
+    git_svc.commit.return_value = {"sha": "deadbeef"}
+
+    deps = _make_deps(task=task_svc, git=git_svc)
+    actions = ContentActions(deps)
+
+    await actions.commit(
+        agent_id=aid,
+        message="[wrong-id] feat(api): add login endpoint for session bootstrap",
+    )
+
+    msg = git_svc.commit.await_args.kwargs["message"]
+    assert msg.startswith(expected_prefix)
+    assert "[wrong-id]" not in msg
+
+
+@pytest.mark.asyncio
+async def test_commit_prefix_collapses_multiple_spaces() -> None:
+    """`[old]   foo` should become `[new] foo`, not `[new]   foo`."""
+    aid = uuid4()
+    tid = uuid4()
+    expected_prefix = f"[{str(tid)[:8]}]"
+
+    t = MagicMock(
+        id=tid,
+        assigned_to=aid,
+        plan="x",
+        status="in_progress",
+        branch_name="feature/backend/abcd1234",
+    )
+    task_svc = AsyncMock()
+    task_svc.get_active_task_for_agent.return_value = t
+    git_svc = AsyncMock()
+    git_svc.commit.return_value = {"sha": "deadbeef"}
+
+    deps = _make_deps(task=task_svc, git=git_svc)
+    actions = ContentActions(deps)
+
+    await actions.commit(
+        agent_id=aid,
+        message="[old]   feat(api): add login endpoint for session bootstrap",
+    )
+
+    msg = git_svc.commit.await_args.kwargs["message"]
+    # Exactly one space after the prefix bracket
+    assert msg.startswith(f"{expected_prefix} feat(api):"), (
+        f"expected single-space prefix; got {msg!r}"
+    )

tests/unit/gateway/test_content_actions.py

@@ -109,9 +109,11 @@ async def test_commit_no_active_task_returns_invalid_state() -> None:
 
 @pytest.mark.asyncio
 async def test_commit_strips_existing_task_prefix() -> None:
-    """Agent-supplied [task-id] prefix is stripped before validation."""
+    """Agent-supplied [task-id] prefix is stripped before validation;
+    the canonical [task-id-short] is re-applied before git.commit."""
     agent_id = uuid4()
     task_id = uuid4()
+    expected_prefix = f"[{str(task_id)[:8]}]"
     task_obj = MagicMock(
         id=task_id, status="in_progress", branch_name="feature/backend/abc"
     )
@@ -130,9 +132,11 @@ async def test_commit_strips_existing_task_prefix() -> None:
     body = env.as_dict()
 
     assert body["error"] is None
-    # The subject passed to git.commit should not include the prefix
+    # The subject passed to git.commit gets the canonical prefix re-applied,
+    # not the user-supplied [ABC12345].
     call_kwargs = git_svc.commit.call_args.kwargs
-    assert not call_kwargs["message"].startswith("[")
+    assert call_kwargs["message"].startswith(expected_prefix)
+    assert "[ABC12345]" not in call_kwargs["message"]
 
 
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