feat(discord): opt-in raw-reaction journal for durable triage state

[Kyzcreig]

What

When discord.reaction_journal (config.yaml) is set, the Discord adapter requests the non-privileged reactions intent and subscribes to on_raw_reaction_add/remove, appending one JSON line per raw transition to that path in the reaction_state core's journal schema: {channel_id, message_id, emoji, user_id, action, seq, ts}.

Why

Raw reaction events fire regardless of message cache, so a reaction on an old / un-cached message is still captured — the durable-triage use case (greenhouse seed_triage, which currently approximates this with a REST poller). This taps the gateway's existing Discord connection rather than opening a second gateway session on the same bot token (which Discord forbids).

Footprint / safety (per AGENTS.md rubric)

• Edge feature, not core surface — lives entirely in the Discord adapter; no new model tool, no core change.
• Config-gated in config.yaml, not a new HERMES_* env var (the path is non-secret config).
• Default OFF — without the config key, no intent change, no extra gateway traffic, zero behavior change. Concrete consumer exists (seed_triage), so it's not speculative.
• Best-effort writes — a journal error can never crash the gateway event loop (runs inside a discord.py handler).
• Restart-safe seq — the monotonic counter seeds from the existing journal's max so a gateway restart never rewinds it.

Tests

tests/gateway/test_discord_reaction_journal.py (7, all green): exact-schema, custom-emoji name:id, add→remove ordering, restart-safe seq, unconfigured no-op, never-raises-on-bad-payload, and an end-to-end ingest by the reaction_state core proving byte-compatibility. Existing adapter suite stays green (27 in test_discord_connect).

[github-actions]

🔎 Lint report: feat/discord-reaction-journal vs origin/main

ruff

Total: 0 on HEAD, 0 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 0 pre-existing issues carried over.

ty (type checker)

Total: 12214 on HEAD, 12212 on base (🆕 +2)

🆕 New issues (2):

Rule	Count
unresolved-import	1
invalid-argument-type	1

First entries

tests/gateway/test_discord_reaction_journal.py:197: [unresolved-import] unresolved-import: Cannot resolve imported module `pytest`
tests/gateway/test_discord_reaction_journal.py:201: [invalid-argument-type] invalid-argument-type: Argument to function `module_from_spec` is incorrect: Expected `ModuleSpec`, found `ModuleSpec | None`

✅ Fixed issues: none

Unchanged: 6399 pre-existing issues carried over.

Diagnostics are surfaced as warnings — this check never fails the build.

[greptile-apps]

Greptile Summary

This PR adds an opt-in raw-reaction journal to the Discord adapter: when discord.reaction_journal is set in config.yaml, the adapter requests the non-privileged reactions gateway intent and writes one JSON line per raw add/remove transition to a configurable file path, enabling the downstream reaction_state / seed_triage consumer to durably track reactions regardless of message-cache state.

• Core path: all journal code is gated on _reaction_journal_path; without the config key nothing changes — no extra intent, no extra gateway traffic, no new behaviour.
• Thread-safe seq generation: double-checked locking with a module-level _REACTION_SEQ_INIT_LOCK ensures the per-instance _reaction_seq_lock is initialised exactly once even under concurrent burst events; the lock then serialises read-increment-write so no two threads can mint the same seq.
• All three previously identified issues are addressed: non-dict journal lines are skipped (no AttributeError-induced silent silencing), makedirs is guarded by a once-per-process flag, and file writes are offloaded to run_in_executor so an emoji storm cannot stall the gateway loop.

Confidence Score: 5/5

Safe to merge — the feature is entirely opt-in, defaults to off, and the three previously identified issues are all correctly resolved in this iteration.

The changed code is well-scoped to the Discord adapter with no core changes. Thread safety is handled correctly via double-checked locking. All defensive except blocks prevent journal errors from propagating to the gateway event loop. The test suite covers concurrency, edge-case journal lines, restart-safe seq, and downstream ingest compatibility.

No files require special attention.

Important Files Changed

Filename	Overview
plugins/platforms/discord/adapter.py	Adds _next_reaction_seq, _emit_reaction_journal, and _append_reaction_journal with correct double-checked locking, run_in_executor offload, and defensive exception handling; all three issues flagged in prior review rounds are fully addressed.
tests/gateway/test_discord_reaction_journal.py	Nine tests covering exact schema, custom-emoji format, ordering, restart-safe seq, non-dict-line resilience, concurrent uniqueness (16-thread barrier test), no-op when unconfigured, bad-payload swallowing, and downstream ingestibility by the reaction_state core.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Discord Gateway
    participant DiscordAdapter (event loop)
    participant ThreadPool (executor)
    participant Journal File

    Discord Gateway->>DiscordAdapter (event loop): on_raw_reaction_add/remove(payload)
    DiscordAdapter (event loop)->>DiscordAdapter (event loop): _emit_reaction_journal(payload, action)
    DiscordAdapter (event loop)->>ThreadPool (executor): run_in_executor(_append_reaction_journal)
    Note over DiscordAdapter (event loop): returns immediately — loop not blocked

    ThreadPool (executor)->>ThreadPool (executor): _next_reaction_seq() [acquire _reaction_seq_lock]
    Note over ThreadPool (executor): First call: seed from existing journal max seq
    ThreadPool (executor)->>Journal File: read existing lines (seed only)
    Journal File-->>ThreadPool (executor): max seq found
    ThreadPool (executor)->>ThreadPool (executor): seq += 1, store _reaction_seq, release lock

    ThreadPool (executor)->>Journal File: append {channel_id, message_id, emoji, user_id, action, seq, ts}
    Journal File-->>ThreadPool (executor): write complete
    ThreadPool (executor)-->>DiscordAdapter (event loop): future resolved (best-effort)

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant Discord Gateway
    participant DiscordAdapter (event loop)
    participant ThreadPool (executor)
    participant Journal File

    Discord Gateway->>DiscordAdapter (event loop): on_raw_reaction_add/remove(payload)
    DiscordAdapter (event loop)->>DiscordAdapter (event loop): _emit_reaction_journal(payload, action)
    DiscordAdapter (event loop)->>ThreadPool (executor): run_in_executor(_append_reaction_journal)
    Note over DiscordAdapter (event loop): returns immediately — loop not blocked

    ThreadPool (executor)->>ThreadPool (executor): _next_reaction_seq() [acquire _reaction_seq_lock]
    Note over ThreadPool (executor): First call: seed from existing journal max seq
    ThreadPool (executor)->>Journal File: read existing lines (seed only)
    Journal File-->>ThreadPool (executor): max seq found
    ThreadPool (executor)->>ThreadPool (executor): seq += 1, store _reaction_seq, release lock

    ThreadPool (executor)->>Journal File: append {channel_id, message_id, emoji, user_id, action, seq, ts}
    Journal File-->>ThreadPool (executor): write complete
    ThreadPool (executor)-->>DiscordAdapter (event loop): future resolved (best-effort)

Loading

_{Reviews (3): Last reviewed commit: "fix(discord): lock reaction-seq generato..." | Re-trigger Greptile}