Board Program LEARN context, ruff 0.16, and verb-rejection observability (#700)

* fix(board): LEARN decisions name the item, not its per-cycle index

A cycle's reject reasons are rendered into the NEXT cycle's exploration
prompt, but the ref recorded alongside each reason was the item's stored
id (item-0/item-1) — a per-cycle index that means something different
every cycle and appears nowhere the explorer can resolve. The reason
survived the loop; what it was about did not.

Record the item's title instead, via a shared learn_ref() helper (falls
back to the id when title-less, and reads target_task_title for Scales,
whose items name the live task they mutate).

* chore(lint): satisfy ruff 0.16 — keyword-only signatures and markdown formatting

The dev toolchain resolved ruff 0.16.0, which stabilises PLR0917 (too many
positional arguments) and formats python code blocks inside markdown. Both
fired repo-wide and neither had anything to do with the code they flagged.

- 36 signatures gain a `*` so their tail arguments are keyword-only, and
  the 104 call sites that passed them positionally are converted. mypy was
  the safety net for the static ones; the full suite caught nine more that
  only bind at runtime (the MCP tool functions, whose real callers already
  pass named JSON arguments).
- 28 markdown files reformatted by 0.16's code-block formatter.
- One RUF036 (`None` mid-union) autofixed in the GitLab provider.

* fix(gateway): log the reason when a verb rejects

A rejected envelope rides an HTTP 200, its body is never logged, and there
is no trace table — so in the access log a verb an agent could not satisfy
looks identical to one that worked. On 2026-07-25 four Board Programs
(Periscope, Sentinel, Scales, Barfly) each POSTed their propose verb three
or four times, persisted nothing, and left their exploration tasks PENDING;
the reason was unrecoverable afterwards, from the logs or from the agents'
own transcripts.

Log error/message/remediate/missing plus the calling agent at
envelope_to_response — the one chokepoint every v1 flow and do route
returns through. Success envelopes stay silent.

---------

Co-authored-by: Renn F <rennf93@users.noreply.github.com>

tests/unit/api/routes/v1/test_flow_dev.py

@@ -77,9 +77,9 @@ async def test_i_will_work_on_dispatches_task_id() -> None:
     assert body["status"] == "in_progress"
     mock_chore.i_will_work_on.assert_awaited_once()
     call_args = mock_chore.i_will_work_on.call_args
-    # second positional arg is task_id (UUID), third is plan
-    assert str(call_args.args[1]) == _TASK_ID
-    assert call_args.args[2] == "implement the feature"
+    # the verb's params are keyword-only past agent_id, so read the kwargs
+    assert str(call_args.kwargs["task_id"]) == _TASK_ID
+    assert call_args.kwargs["plan"] == "implement the feature"
 
 
 @pytest.mark.asyncio

tests/unit/api/routes/v1/test_verb_rejection_logging.py

@@ -0,0 +1,60 @@
+"""A rejected envelope must leave a server-side trace.
+
+An error envelope rides a 200, so the access log cannot distinguish a verb an
+agent could not satisfy from one that worked. Four Board Programs died that
+way on 2026-07-25 with no recoverable reason.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+from unittest.mock import MagicMock
+
+from roboco.api.routes.v1._role_dep import envelope_to_response
+from roboco.services.gateway.envelope import Envelope
+from structlog.testing import capture_logs
+
+
+def _request(path: str) -> MagicMock:
+    request = MagicMock()
+    request.url.path = path
+    request.state.correlation_id = "cid-1"
+    request.headers = {"X-Agent-ID": "agent-7", "X-Agent-Role": "head_marketing"}
+    return request
+
+
+def _captured(env: Envelope, path: str) -> list[Any]:
+    """``capture_logs`` rather than a hand-rolled processor swap — it is
+    independent of whatever global structlog config the rest of the suite has
+    already installed, which made the swap pass alone and fail in-suite."""
+    with capture_logs() as entries:
+        envelope_to_response(env=env, request=_request(path))
+    return [e for e in entries if e.get("event") == "verb rejected"]
+
+
+def test_rejection_logs_reason_and_remediation() -> None:
+    env = Envelope.invalid_state(
+        message="finding 0 is missing 'source_url' — an uncited market claim is noise",
+        remediate="provide the http(s) source URL finding 0's claim came from",
+        context_briefing={},
+    )
+    entries = _captured(env, "/api/v1/do/propose_market_brief")
+
+    assert len(entries) == 1, entries
+    logged = entries[0]
+    assert logged["verb"] == "propose_market_brief"
+    assert logged["error"]
+    assert "source_url" in str(logged["detail"])
+    assert "http(s) source URL" in str(logged["remediate"])
+    assert logged["agent_id"] == "agent-7"
+    assert logged["agent_role"] == "head_marketing"
+
+
+def test_success_envelope_logs_nothing() -> None:
+    env = Envelope.ok(
+        status="market_brief_proposed",
+        task_id="t-1",
+        next="i_am_idle()",
+        context_briefing={},
+    )
+    assert _captured(env, "/api/v1/do/propose_market_brief") == []