Sync upstream 4.31 (next wave after 0.4.30)

[patrick-chinchill]

Upstream is at chat@4.31.0. Net-new vs 4.30.0 (per the per-package CHANGELOGs):

Core chat@4.31.0:

• chat/adapters — zero-dependency adapter catalog subpath (metadata, environment specs, setup helpers) (778ae69)
• Stable IDs for link-button action handlers (171657a)

Adapters (net-new code, not just dep bumps):

• Slack — webClientOptions config passthrough (8336a3e); @mention rewriting fix for handles inside URLs (a8bf99a); stable link-button IDs
• Teams — low-level Teams primitive subpaths for custom runtimes (8c71411)
• Telegram — native rich formatting + streaming for Bot API 10.1 (4662309); route Telegram bot commands to slash-command handlers (9c936f8)
• state-ioredis — optional logger (8f3af76)

All other adapters/state = dependency bumps only.

Also fold in the pre-4.30 gap deferred from this wave:

• Linear agent sessions — Port Linear agent sessions (adapter-linear) — deferred from 0.4.30 #151

Most of the raw 4.30→4.31 file diff is the apps/docs marketing site (not ported).

[coderabbitai]

🔗 Related PRs

#48 - fix: adapter hygiene — Slack stream await, Teams divider, public worker APIs [merged]
#83 - sync: upstream v4.27.0 (alpha 1) [merged]
#89 - fix(adapters): bug-fix sweep from upstream 4.27.0 (slack/discord/telegram) [merged]
#106 - release: 0.4.27 — synced to upstream vercel/chat@4.27.0 [merged]
#134 - release: 0.4.29 completion train — stranded-PR recovery + remaining 4.29 ports + cut [merged]

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[patrick-chinchill]

4.31 port plan (scoped 2026-06-19)

Decomposed into 5 waves, ~26-30 eng-days. Fidelity re-pin is string-only (mapped-core test files byte-identical 4.30→4.31); the version cut does not depend on the big pieces, so 0.4.31 can ship incrementally.

• Wave A — small parity (~4-5d, starting now): core stable LinkButton id (171657a); Slack webClientOptions (8336a3e) + @mention-in-URL regex fix (a8bf99a) + stable action_id; Telegram slash-command routing (9c936f8).
• Wave B — Teams primitive subpaths (~7-8d): teams/{format,webhook,cards,modals,api,graph} (8c71411) — additive, SDK-free, no conflict with the 0.4.30 migration; adds 2 SSRF allowlist divergences (api/graph).
• Wave C — Telegram rich (~7-8.5d, high risk): Bot API 10.1 rich formatting + streaming (4662309); new rich.py; rewrites the stream path (demotes the feat(telegram): native DM draft streaming (4.30 — vercel/chat#340) #140 MarkdownV2 draft path to a fallback tier).
• Wave D — Linear agent sessions (Port Linear agent sessions (adapter-linear) — deferred from 0.4.30 #151, ~7.25d, highest risk): the deferred 4.27 gap; re-expressed as raw GraphQL (no @linear/sdk).
• Wave E: ioredis logger (already structurally satisfied) + 0.4.31 version cut.

Decisions: chat/adapters catalog (778ae69) → skip (npm/Vercel-docs metadata, no Python runtime consumer, 12/22 entries are adapters we don't ship) and document as non-parity. Per-piece review gate applies. Wave A starting; B/C/D reassessed after A lands.

[patrick-chinchill]

Completed in 0.4.31 (released to PyPI 2026-06-20). All five waves landed (Linear agent-sessions #151, Teams primitive subpaths, Slack 4.31, Telegram rich, ThinkingChunk); UPSTREAM_PARITY = "4.31.0". See the 0.4.31 CHANGELOG. Upstream is now at parity (latest tag chat@4.31.0); the next sync starts when chat@4.32.0 lands.