fix: restore Discord auto-threading with free-response channels

[hdiesel323]

Summary

• Decouples Discord free_response_channels from auto-thread creation so free_response_channels: '*' no longer bypasses thread routing.
• Adds a WT-style Discord thread label registry for machine-readable thread metadata.
• Adds regression coverage for free-response auto-threading and thread-label loading.

Test Plan

• pytest tests/ → 369 passed, 2 warnings

Linear

• Project: https://linear.app/redcloudventures/project/discord-thread-routing-labels-sprint-2026-05-27-815a5f124abc
• Epic: https://linear.app/redcloudventures/issue/RED-500/epic-discord-auto-thread-routing-policy-wt-style-thread-labels
• Tasks: RED-501, RED-502, RED-503, RED-504, RED-505

[alt-glitch]

Duplicate of #13958 (oldest open). This is the 8th+ PR attempting to decouple free_response_channels from auto-thread suppression in the Discord adapter. Competing open PRs: #13958, #18455, #18592, #27651, #29981, #31852. The root issue is #26058.

[austinpickett]

Request Changes

The core fix (removing or is_free_channel from skip_thread) is correct — the bug is still present on main and this is the right one-line change. However, this PR is over-scoped relative to the stated bug fix:

🔴 Scope creep / smuggled content:

1. thread_labels.py + thread_labels.json — a new thread-metadata registry (wtupdate/wtsignoff labels, [labels: ...] appended to thread names). This is a new feature, not a bug fix. Belongs in its own PR.
2. vercel==0.5.7 added to pyproject.toml optional deps — unexplained. Unrelated to Discord threading. Please remove.
3. No CI run on this branch.

Coordination note: This is the 8th+ attempt at this fix (related canonical PRs: #13958 [P1, open], #31852). Before merging, this should either consolidate into or supersede the canonical issue. I'd recommend: \n- Strip to just the 1-line fix in adapter.py + the updated test\n- Remove vercel dep + thread-labels feature (separate PR)\n- Then resolve against #13958/#31852 for deduplication

[teknium1]

Thanks for the regression coverage and for identifying the configuration tension.

Problems

• The routing change at plugins/platforms/discord/adapter.py:4558 reverses main's intentional default: current plugins/platforms/discord/adapter.py:6223, docs at website/docs/user-guide/messaging/discord.md:377, and test tests/gateway/test_discord_free_response.py:658 keep free-response channels inline. Commit 232f5079f introduced that behavior specifically to avoid creating a thread for every mention-free message.
• The label registry only appends parsed bracket tokens to formatted chat names in this diff; it is unrelated to routing and should not be coupled to this policy change. The vercel extra in pyproject.toml is likewise unrelated.

Suggested changes

• Keep the current inline default and, if maintainers select this product direction, re-scope to an explicit documented discord.* opt-in for threaded free-response channels, with coverage for both default and opt-in behavior.
• Split the label-registry and dependency changes into separate, independently justified work.

Automated hermes-sweeper review.

[teknium1]

This removes the intentional free-response inline guard. Current main retains the equivalent condition at plugins/platforms/discord/adapter.py:6223; commit 232f5079f and tests/gateway/test_discord_free_response.py:658 establish it as the documented default. Please preserve that default and add a separate explicit opt-in if threaded free-response channels are selected as a supported mode.