(CODUX-225) Complete the Discord connector

[numnx]

🧩 Task: Complete the Discord connector

Automated task PR opened by Code UX for T02.

📋 Summary

Sprint: Sprint 225 · Chat connector completeness and verification · Task: T02

Complete and verify all six chat connectors through provider-specific profiles, correct authentication and session behavior, encrypted durable state, atomic routing and retries, REST/MCP/dashboard management, official-documentation evidence, deterministic contract coverage, and credential-gated checks limited to provider-controlled endpoints, with Discord prioritized.

🤖 Model & Provider

Provider	Codex CLI
Model	gpt-5.6-sol

⏱️ Timing

Started	2026-07-13 22:51:00 UTC
Finished	2026-07-13 23:10:30 UTC
Duration	19m 29s

📊 Token Usage

Metric	Value
Input tokens	192,440
Cached input tokens	7,266,304
Output tokens	43,170
Total tokens	7,501,914
Invocations	1
Tool calls	46
Active time	18m 33s

Included usage estimate (subscription/local login): $5.89

✅ QA Review

⏳ QA review runs after this PR is opened. Check the task card in the dashboard for the outcome once it lands.

📝 Full Task Prompt

## Objective
Complete the Discord profile with provider-native HTTP interaction authentication, stateful Gateway message delivery, REST replies, credential verification, deterministic failure handling, and backward-compatible custom gateway support.

## Scope
- `src/domain/chat-connectors/providers/discord.ts`
- Create `src/services/chat-providers/discord-gateway-session.ts`
- Create `tests/backend/domain/chat-connectors/discord.test.ts` and `tests/backend/services/discord-gateway-session.test.ts`
- `docs/settings/chat-connectors/discord.md`
- `docs-web/architecture/chat-connectors/discord.md`
- Official references: [Gateway](https://docs.discord.com/developers/events/gateway), [Gateway events](https://docs.discord.com/developers/events/gateway-events), [Interactions](https://docs.discord.com/developers/interactions/overview), [Messages](https://docs.discord.com/developers/resources/message), and [Rate limits](https://docs.discord.com/developers/topics/rate-limits)

## Implementation Requirements
1. Add an `official_api` setup using application ID, public key, intents, and a write-only bot token while retaining the existing `webhook` gateway contract for stored connections.
2. Verify HTTP interactions with `X-Signature-Ed25519` and `X-Signature-Timestamp` over the exact raw body, reject malformed or stale requests, and return the required PONG response for type-1 validation requests.
3. Normalize supported interaction payloads and Gateway `MESSAGE_CREATE` events into stable channel, sender, message, and thread identities; ignore the connector bot's own messages and explain the privileged `MESSAGE_CONTENT` intent requirement.
4. Implement Gateway identify/resume, sequence tracking, heartbeat jitter and acknowledgements, missed-ACK reconnects, resumable session state, bounded exponential reconnect backoff, cancellation, and clean shutdown through the shared session-store interface from T01.
5. Send replies only to `https://discord.com/api/v10`, disable automatic mentions with `allowed_mentions.parse: []`, use a stable delivery nonce with `enforce_nonce` where supported, preserve reply references, parse returned snowflake IDs, and honor Discord rate-limit headers without retry storms.
6. Implement read-only credential verification through Discord's current-user endpoint and classify invalid auth, missing intents/permissions, 429 responses, timeouts, and ambiguous network outcomes without exposing tokens.
7. Cover valid and invalid Ed25519 signatures, PING, message normalization, bot-loop suppression, heartbeat/reconnect/resume, rate limiting, cancellation, legacy gateway behavior, and redaction with deterministic fixtures and mocked transports.

## Constraints
- Unit tests must never connect to Discord; the credential-gated live suite is owned by T13.
- Never permit a configured URL to replace the provider-controlled Discord API origin in `official_api` mode.
- Do not persist bot tokens, interaction tokens, or authorization headers in Gateway state or delivery metadata.
- Do not modify other provider modules or shared generated docs-web artifacts.

## Verification
- Run `pnpm run test:backend -- tests/backend/domain/chat-connectors/discord.test.ts tests/backend/services/discord-gateway-session.test.ts`.
- Run `pnpm run lint`.
- Confirm simulated disconnects resume when possible, fall back to identify when required, and stop reconnecting after cancellation or shutdown.

🌿 Branch Info

Base: feature/CODUX-225-chat-connector-completeness-and-verification
Head: task/feature-codux-22-t02-codex-1f9c0cde-mrjtgd0y

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🤖 Generated by Code UX