fix(relay): restore streaming delivery, Slack command parity, and status clearing (salvage of #69716)

[benbarclay]

Summary

Salvage of #69716 (@victor-kyriazakos) over current main, resolving the collision with #69721 which merged send_typing twenty minutes after that PR opened. The contributor's three commits are carried as-is (authorship preserved in history); the merge commit reconciles the overlap.

Restores relay-delivered Slack presentation and command parity:

• Streaming delivery: _adapter_for_source() routes presentation callbacks (streamed edits, typing, tool progress) for delivered_via_upstream_relay events through the process-level RelayAdapter instead of a possibly-absent native platform adapter. Source identity, authz, and session semantics are unchanged; registered transport-adapter provenance stays highest priority (multiplexed-profile behavior preserved).
• edit_message over relay: new op="edit" frames with _with_scope() + Phase 1.5 platform tag, mirroring send().
• Slack Assistant status clear: stop_typing() emits an empty-content typing frame, Slack-gated (one-shot platforms are untouched).
• /hermes parent-command normalization at the wire boundary, matching the native Slack adapter (subcommand map, compact → /compress, free-form text passthrough, /hermes → /help). Non-Slack relay events unchanged.

What the salvage changes vs. #69716

• Kept main's shipped send_typing (from feat(relay): egress typing indicators through the connector (op="typing") #69721) — it wraps the frame in try/except ("typing is cosmetic, never breaks a turn"); dropped the PR's unguarded duplicate.
• Added the same try/except guard to the new stop_typing for parity, plus a regression test that a transport failure at end-of-turn does not raise.
• Contract doc updated: §4 typing row now documents content?, with a semantics note (empty string = Slack status clear) — the lockstep edit feat(relay): egress typing indicators through the connector (op="typing") #69721 set precedent for.
• Removed the PR's send_typing test (superseded by main's five-test suite for the shipped implementation).

Operational flag — deploy order

gateway-gateway #154 must deploy before this reaches any hosted gateway. A connector predating #154 hardcodes status: "is typing…" for the typing op, so an empty clear frame would set the status instead of clearing it — a permanently stuck "is typing…" after every turn. The reverse order is safe. This is noted in the stop_typing docstring and the contract doc.

Verification

• tests/gateway/relay/ full suite: 188 passed (includes the merged adapter + contract-doc conformance).
• test_multiplex_profile_authz.py + test_stream_consumer.py + test_slack_relay_parent_command.py: 144 passed.
• ruff check clean on all touched files; git diff --check clean; no conflict markers.
• Run from inside the worktree with PYTHONPATH pinned to the checkout.

Credit

All substantive work by @victor-kyriazakos in #69716; his commits are carried directly. The relay-delivered flows were exercised by the original author against a real shared Slack connector deployment (see #69716's verification section).

Infographic

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debug info

CI timings

CI timings · View job

Wall time 9m27s vs 9m19s (+1.4%). 10 job(s) slower, 10 faster,

• Build&Test Docker image / build (arm64, ubuntu-24.04-arm, linux/arm64, type=gha,scope=docker-arm64, type=gha,mode=max,scope...: +112.0s
• Python tests / Run tests slice 3/8: -46.0s
• Python tests / Run tests slice 5/8: -40.0s
• Python tests / Run tests slice 6/8: -38.0s
• Python tests / Run tests slice 2/8: +38.0s