fix(simplex): escalate non-retryable WebSocket handshake rejections instead of looping forever

[lambertian]

Summary

When the simplex-chat daemon rejects the WebSocket handshake with an HTTP status (e.g. a permanently misconfigured endpoint, wrong path, or auth failure), the websockets client raises InvalidStatus. Because InvalidStatus is a subclass of WebSocketException, the SimpleX adapter's reconnect loop (_ws_listener) caught it in the generic reconnect arm and busy-looped forever with exponential backoff — never surfacing a gateway-visible fatal state, so operators got no signal that the connection could never succeed.

This adds a specific arm that catches the handshake-rejection exception and inspects the HTTP status:

• 4xx (permanent misconfiguration that can never succeed on retry) → call _set_fatal_error("handshake_rejected", ..., retryable=False) and break out of the reconnect loop, matching the fatal-error convention used by the base adapter and siblings (e.g. IRC, Mattermost's permanent-auth-failure stop).
• 5xx / unknown → treated as potentially transient and left to the existing reconnect path, so behavior there is unchanged.

Transient errors (ConnectionClosed, other WebSocketExceptions) keep retrying exactly as before.

A small helper, _handshake_status_code, reads the status from either the newer InvalidStatus (.response.status_code) or the older InvalidStatusCode (.status_code), and the import is guarded so the adapter works across websockets versions.

Tests

Added two focused async tests to tests/gateway/test_simplex_plugin.py:

• test_ws_listener_escalates_4xx_handshake_rejection — patches websockets.connect to raise a real InvalidStatus(403), runs _ws_listener, and asserts _set_fatal_error is called exactly once with retryable=False and the loop exits. It wraps the listener in asyncio.wait_for(..., timeout=5) so the old busy-loop behavior fails fast instead of hanging.
• test_ws_listener_retries_5xx_handshake_rejection — a 503 rejection is retried (loop does not escalate), guarding against over-broad escalation.

The 4xx test is red on current main (the handshake rejection falls into the generic reconnect arm and the loop never exits, tripping the 5s timeout) and green with this change. The 5xx test passes both before and after, confirming transient behavior is preserved.

(One unrelated test in the file, test_standalone_send_missing_url, is environment-dependent and is not affected by this change; where it fails, it fails identically on clean main.)

Notes

• Against websockets 15.0.1 the rejection class is InvalidStatus (exposing .response.status_code); the code and tests also handle the older InvalidStatusCode alias for portability across versions.
• Overlap with feat(simplex): groups, native attachments, text batching, auto-accept #27978: it edits the same _ws_listener region (narrowing the generic catch from WebSocketException to ConnectionClosed plus a bare except Exception), but it adds no handshake-rejection / 4xx fatal handling — so even under feat(simplex): groups, native attachments, text batching, auto-accept #27978 a 4xx InvalidStatus would still fall through and loop forever. This fix is not a duplicate; it stands on its own against current main, and if feat(simplex): groups, native attachments, text batching, auto-accept #27978 lands first it slots into the restructured loop as a small mechanical rebase. No other open SimpleX PR (fix(simplex): make websocket handling reliable #26480, fix(simplex): avoid reconnecting healthy idle WebSocket #27120, fix(simplex): make polling recovery visible and bounded #27415, Fix(gateway): 3 bugs blocking bidirectional simpleX messaging #26433, fix(simplex): propagate WebSocket send failures to SendResult #27628) touches handshake/fatal escalation.

[tonydwb]

Code Review Summary

Verdict: Approved ✅

Review Findings

This PR escalates non-retryable 4xx WebSocket handshake rejections to a fatal error state instead of busy-looping forever. Previously, a permanently misconfigured daemon (wrong path, auth failure) would cause infinite reconnection attempts with no operator signal.

✅ Looks Good

• Design: Clear distinction between 4xx (permanent — fatal escalation) and 5xx/unknown (transient — keep retrying). This matches the adapter pattern used by IRC and Mattermost.
• _handshake_status_code helper: Handles both websockets >= 14 (InvalidStatus.response.status_code) and older InvalidStatusCode.status_code — good cross-version compatibility.
• Import guard: The try/except import for InvalidStatus/InvalidStatusCode is clean and maintainable.
• Error message: "SimpleX daemon rejected WebSocket handshake (HTTP {status})" — informative and actionable.
• Tests:
  • test_ws_listener_escalates_4xx_handshake_rejection — patches websockets.connect with a real InvalidStatus(403), verifies _set_fatal_error called exactly once with retryable=False, and uses asyncio.wait_for(timeout=5) to catch the old busy-loop behavior.
  • test_ws_listener_retries_5xx_handshake_rejection — verifies 503 keeps retrying without escalation, guarding against over-broad escalation.
• Diff: 157 additions, 0 deletions — all new code, no risk of regression.

No Issues Found

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Reviewed by Hermes Agent

[tonydwb]

Code Review Summary

Verdict: Approved ✅

Review

Fixes SimpleX WebSocket handshake rejection causing an infinite reconnect loop. 4xx handshake rejections (permanent misconfiguration) now escalate to fatal error instead of retrying forever.

✅ Looks Good

• Correct escalation: 4xx → fatal, non-retryable. 5xx → still retried as potentially transient.
• Version-safe: Handles both newer InvalidStatus and older InvalidStatusCode from websockets library.
• Good test coverage: Two focused async tests — 4xx escalates, 5xx retries.
• Prevents operator-blind failures: Gateway-visible fatal state means operators get a signal instead of silent busy-loop.

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Reviewed by Hermes Agent (cron job)

[teknium1]

Thanks for isolating a real reconnect-loop gap. Current main still catches a rejected InvalidStatus in the generic retry arm at plugins/platforms/simplex/adapter.py:332-344; a controlled 403 repro logged a reconnect and left fatal_error unset.

Problems

• plugins/platforms/simplex/adapter.py:284 treats every 4xx as permanently fatal. The PR proves 403, but the condition covers the entire 400–499 range. Existing auth-retry coverage is explicit about terminal 401/403 (tests/gateway/test_ws_auth_retry.py:21-77); please define the SimpleX-specific terminal set and preserve retry for transient or ambiguous 4xx cases.
• The new 4xx test mocks _set_fatal_error (tests/gateway/test_simplex_plugin.py:365-375), so it does not verify the gateway-visible state produced by BasePlatformAdapter._set_fatal_error() (gateway/platforms/base.py:2705-2710).

Suggested changes

• Add a retry regression test for a non-terminal 4xx status alongside 403 and 503.
• Exercise the real fatal setter while mocking its status writer, then assert the fatal fields and _running state.

Automated hermes-sweeper review.

[teknium1]

This makes every 4xx terminal, although the demonstrated permanent case is 403. Please use an explicit SimpleX-specific terminal-status set and add coverage for a transient or ambiguous 4xx response so this does not turn a recoverable rejection into a permanently disabled adapter.

[teknium1]

Mocking _set_fatal_error verifies the call but bypasses the gateway-visible state this PR is intended to establish. Prefer mocking _write_runtime_status_safe and assert the real setter leaves _running false and records the expected fatal fields.