Round 2 of the approval-turn stuck-stream hunt. Round 1 (interim-marked
acks) fixed the draft-hijack-by-matching path — live logs confirm the
absorption fallback no longer fires — but the freeze persisted because
of a second, deeper defect on the same codepath:
_consume_prompt_response executes ON the transport read loop (inbound
frame -> _handle_frame -> _inbound handler). The handler awaited
self.send() for its '✅ Approved once' ack — but send() blocks on an
outbound_result future that ONLY the read loop can resolve, and the
read loop is blocked inside this very handler. Guaranteed self-deadlock
for the full outbound timeout (30s) on EVERY button tap. While wedged,
everything on the transport starved: draft appends (the frozen stream
right after approving), sibling approval-card sends (timed out into
'possibly-delivered' — the observed double-approval ambiguity), and the
turn's seal (timed out ambiguous -> plain-send fallback -> duplicate
final). Log signature was the tell: card-send timeout at tap time, no
absorption INFO, no seal-failed WARNING, no suppression line.
Fix: _send_lifecycle_ack() — acks ride a background task with strong
ref retention; the handler returns immediately and the read loop keeps
consuming, so the ack's own result frame resolves normally. Applied to
all six lifecycle sends (approval ack, slash-confirm ack + result text,
clarify acks, expiry notice). Acks are cosmetic by contract; failure
logs at debug and never breaks the reader.
Tests: new deadlock-shape test (gated transport send; handler must
return within 1s and the ack must still egress afterwards — RED on the
awaited version via TimeoutError at the exact deadlock), prior 3 tests
green with a yield for the background task. Targeted sweep 203/203.
Live finding (rc.4 staging, 100% reproducible on approval turns): after
resolving an exec-approval prompt_response, the adapter sends a short
ack ('Approved once'). _prompt_reply_metadata carried only placement
metadata (thread_id) — no per-turn identity, no interim marker — so
send()'s single-open-stream fallback (review B2) matched the approval
turn's OWN live draft and sealed it with the ack text. From there,
silently: every later append died on the post-seal tombstone (built for
millisecond stragglers, deliberately quiet), freezing the visible draft
mid-word; the turn-final found no open draft and fell through to a
plain send — the duplicate 'fallback' message. No suppression line, no
seal-failed warning: the log signature was pure absence.
Fix: _prompt_reply_metadata stamps _interim_send=True, which send()
already honors by bypassing draft matching. One source covers the whole
lifecycle class (approval ack, slash-confirm ack, prompt-expired
notice — all six call sites route through it).
Observability (the quiet parts, out loud):
- single-open-stream absorption now logs at INFO with the absorbed key;
- the FIRST post-seal tombstone swallow per draft key logs at WARNING
(bounded FIFO dedup) — one swallow is the normal straggler race, a
burst means a live stream was sealed mid-flight by someone else.
Tests (RED-first: both ack tests failed on the unfixed adapter at the
'draft still armed' assertion): approval ack leaves the open draft
armed and egresses as a plain send op; expiry notice same; regression
control pins the B2 contract — a real identity-less turn-final still
absorbs into its single open stream.
Three live findings from rc.4 staging, all on the relay-fronted Slack
path, all with the failure observed in live logs before the fix:
1. Approval-send timeout is AMBIGUOUS, not failed (no re-ask).
send_exec_approval through the connector can time out with the card
already rendered — the connector may ack after the deadline (slow
platform API call, transient backpressure, event-loop stall) — and
the timeout-as-failure path re-sent and produced duplicate cards.
The outcome is now tri-state: sent / failed / ambiguous. Ambiguous =
no re-send, no text fallback; the prompt registration stays armed so
a late tap still resolves. Only a definite send error falls back to
text.
2. pending_approval tool results forbid re-issuing the command.
With one card correctly armed, the agent could still mint a SECOND
card by re-running a rephrased variant of the gated command after
reading the pending_approval tool result (observed live: same
command re-issued in a different form, two cards). The tool message
now instructs: do not re-run/rephrase; wait or report pending.
Applied to both the terminal and execute_code arms.
3. Draft interim AND seal frames carry format_hints.
format_hints are stamped on send, edit, and send_for_platform, but
both draft-frame builders (send_draft interim + _seal_open_draft
seal) shipped bare metadata. A streamed final therefore arrived at
the connector hintless and sealed as a plain code block while
non-streamed sends rendered native markdown blocks (observed live:
language-tagged block on send/edit, downgrade on streamed seal).
Both sites now stamp _with_format_hints_for_chat
(destination-resolved, same pattern as the existing lanes).
Verified live after the fix against the platform's stored message
payload: rich_text_preformatted with language field on a streamed
seal.
Tests: tri-state outcome unit tests (5), draft/seal hint stamping + knobs-
off regression control (2, RED-first), existing format-hints suite intact
(14/14). Mutation-verified: reverting the adapter hunk sends
test_draft_interim_and_seal_frames_carry_hints red; restore -> green.
Boundary sweep (text egress lanes crossing the frame contract): send ✓
(pre-existing) edit ✓ (pre-existing) send_for_platform ✓ (pre-existing)
draft-interim ✓ (this PR) draft-seal ✓ (this PR); task_card lane carries
no text content — exempt.
test_flat_key_wins_over_subblock asserted the OPPOSITE of its name (the
sub-block wins, matching _relay_slack_extra). Rename to what it proves.
Also note in _resolve_cron_surface_mode why its fallback differs from
_relay_slack_extra's all-or-nothing sub-dict: the flat key is the legacy
staging shape, and a flat knob applies to every fronted platform, gated
only by the per-platform D6 capability check.
RelayAdapter.supports_inchannel_continuable is a scalar adopted from the
PRIMARY identity's handshake descriptor, but one RelayAdapter fronts N
platforms and the connector advertises the bit per platform. Reading the
scalar for every logical platform both leaked a Slack-primary True onto
other fronted platforms (activating the flat surface their descriptor
never advertised) and suppressed a non-primary platform's advertised
True (forcing thread mode on capable Slack behind a Discord primary).
Add supports_inchannel_continuable_for_platform(platform): resolves the
platform's own negotiated descriptor via descriptor_for_platform (the
same Phase 1.5 seam max_message_length uses), scalar fallback only when
the per-platform descriptor is unavailable. The scheduler's D6 gate
prefers the query when the adapter provides it; native adapters keep
the class-attribute path byte-identically.
Tests: two-platform descriptor matrix (primary-True no-leak,
non-primary-True honored, unknown-platform scalar fallback).
Two gaps in the block-formatting hint stamping:
1. Wrong descriptor: _format_hints gated on self.descriptor — the PRIMARY
identity's scalar — while one RelayAdapter fronts N platforms. A
Slack-primary adapter stamped Slack hints onto known Discord chats; a
Discord-primary adapter suppressed hints for Slack chats whose own
negotiated descriptor advertised the bit. Resolve per destination:
send/edit use _descriptor_for_chat (the same seam max_message_length
already uses) plus the chat's logical platform for the config
sub-block; the knob lookup is now per-logical-platform
(platforms.relay.extra.<platform>.*) instead of hardwired to slack.
2. Missing lane: send_for_platform — the scheduled/persisted-home lane
(gateway/delivery.py), i.e. the CRON delivery path, the flagship
consumer of the in_channel brief — never stamped hints at all. Stamp
there too, resolving descriptor_for_platform(logical) off the
transport; the scalar descriptor is used only when it belongs to that
exact platform (fail closed).
Tests: Slack-primary/Discord-chat no-leak, Discord-primary/Slack-chat
still-stamps, send_for_platform stamps for capable platform and stays
clean for incapable — all against a two-platform negotiated-descriptor
transport. Existing single-platform suite unchanged and green.
Field report (enterprise side-by-side, 2026-08-18, finding 2): identical
agent output renders native rich_text lists, Block Kit tables, and
highlighted code on native Slack, but literal '-' bullets and code-fence
tables on the relay lane. Native reads platforms.slack.extra.rich_blocks /
markdown_blocks and renders Block Kit locally; relay frames carried no
formatting signal, so the connector had no way to know the operator wants
block rendering.
Contract (additive, v1): the connector advertises supports_block_formatting
in its capability descriptor. When it does AND the operator enables
platforms.relay.extra.slack.rich_blocks / markdown_blocks (same per-platform
sub-block and same _coerce_flag semantics as the other relay Slack knobs),
the gateway stamps format_hints into outbound metadata on BOTH text egress
lanes — send and edit (a streamed reply's final edit carries the finished
markdown, so it must signal too or streams seal as plain text). The
connector renders blocks and keeps plain text as the fallback.
Old connector: never advertises -> no dead metadata ever sent. Old gateway:
never stamps -> connector renders plain text as today. Knobs default OFF,
matching native's opt-in posture.
8 new tests: descriptor default/from_json, hint stamping (capable+enabled),
capability-absent suppression, knobs-off suppression, YAML-quoted-false
coercion, partial knobs, edit-lane parity.
Field report (enterprise side-by-side, 2026-08-18, finding 1 — the relay-only
blocker): on relay-fronted Slack, cron briefs always deliver into a dedicated
thread; the flat continuable surface (cron_continuable_surface: in_channel)
that native Slack supports is inert, so plain DM replies never continue the
job and the main conversation never sees the brief.
Three gaps closed:
- CapabilityDescriptor gains supports_inchannel_continuable (default False,
additive within contract_version 1; from_json ignores it from old
connectors, old gateways filter it as unknown). The connector advertises
it per platform at handshake.
- RelayAdapter maps the bit onto the adapter capability surface in both the
constructor and _apply_descriptor (renegotiation), so the scheduler's D6
fail-safe gate sees it exactly like native Slack's class attribute.
- _resolve_cron_surface_mode replaces the scheduler's inline flat-key read:
native keeps the shipped flat shape; the relay lane reads the same
per-logical-platform sub-block as the documented relay Slack knobs
(platforms.relay.extra.slack.cron_continuable_surface), sub-block wins,
scoped so a slack block cannot leak onto other fronted platforms.
The seed path needs no changes: RelayAdapter inherits set_session_store
(wired by the generic adapter boot loop) and _seed_cron_channel_session
keys the flat session off the logical platform_name.
12 new tests: descriptor default/from_json/legacy-absence, adapter mapping
constructor + renegotiation, and the surface-knob matrix (native flat key,
relay sub-block, per-platform scoping, precedence, defaults).
Victor Kyriazakos