feat(googlechat): full [googlechat] section — credentials + connection config-first

[chaodu-agent]

Note

Stacked on #1382 (→ #1381 → main). Net-new diff = the last commit; will re-target as parents merge.

What problem does this solve?

Third platform slice of #1375: Google Chat's credentials/connection were env-only. [googlechat] graduates from the shared trust-only struct to a dedicated GoogleChatConfig (6 fields + trust), resolving each field config → GOOGLE_CHAT_* env → default.

How It Works

Layer	Change
core	GoogleChatConfig/ResolvedGoogleChat + resolve(); trust_config() view keeps the registry path unchanged
gateway	DRY bonus: adapter construction was copy-pasted between from_env and standalone run() — deduplicated into GoogleChatAdapter::from_parts; GatewayGoogleChatConfig bridge + apply_googlechat_config(); new googlechat_webhook_path state honored by both binaries
unified	Applies [googlechat] before warn_unenforceable_l1 — config-supplied audience builds the JWT verifier and satisfies the #1373 L1 check
docs	example, config-reference (dedicated section), google-chat.md

Tests

• googlechat_resolve_all_scenarios — defaults, config-wins (incl. explicit enabled=false beating env true), empty-string fallthrough, trust_config()
• apply_googlechat_config_builds_adapter_and_feeds_l1_warning — pins the L1 integration: enabled-without-audience flagged → config audience clears → disabled removes adapter

Validation

• clippy -D warnings clean (all-features + gateway no-features); unified + default builds pass
• core 662 passed (1 known pre-existing macOS secrets failure); gateway l1_audit 6/6
• rustfmt isolated: 0 new drift (googlechat.rs 45→45 pre-existing)

Closes #1379. Refs #1375, #1373.

[chaodu-agent]

Note

LGTM ✅ — Clean config-first graduation for [googlechat]: DRY adapter construction, correct resolve-order semantics, solid test coverage.

What This PR Does

Graduates [googlechat] from the shared PlatformTrustConfig (trust-only L3 fields) into a full first-class GoogleChatConfig struct carrying credentials + connection + trust, resolving each field via the project-wide config → env → default cascade (#1379).

How It Works

• core: GoogleChatConfig (8 fields) + ResolvedGoogleChat + resolve(); trust_config() adapter preserves backward compat with the trust registry.
• gateway: GoogleChatAdapter::from_parts deduplicates the token-cache/JWT-verifier construction that was copy-pasted between from_env and serve(); GatewayGoogleChatConfig bridge carries resolved values across crate boundary; googlechat_webhook_path now lives on AppState.
• unified (main.rs): Applies config before warn_unenforceable_l1 so a config-supplied audience builds the JWT verifier and is never falsely flagged.
• docs: config-reference gets a dedicated [googlechat] table; google-chat.md updated; example TOML annotated.

Findings

#	Severity	Finding	Location
1	🟢	DRY win: from_parts eliminates ~40 lines of duplicated adapter construction	googlechat.rs:273
2	🟢	Test pins config-wins-env, empty-string fallthrough, and trust_config() roundtrip in one test	config.rs:2408
3	🟢	L1 integration test covers the full lifecycle: enabled-without-audience → flagged → audience-supplied → cleared → disabled	lib.rs:933
4	🟢	Doc comment on PlatformTrustConfig accurately updated to reflect Teams-only scope	config.rs:978

What's Good (🟢)

• Consistent pattern: follows the exact same structure as the LINE and WeCom config-first slices — easy for future reviewers to understand.
• Backward-compatible: env-only deployments flow through from_parts identically; trust_config() view means the registry override path is untouched.
• ${}-aware empty-string filtering: opt_str properly treats "" (from unexpanded ${}) as unset, falling through to env — a subtle but correct design choice.
• Feature-gate hygiene: #[cfg(not(feature = "googlechat"))] fallback for googlechat_webhook_path prevents compilation errors in minimal builds.

Baseline Check

• PR opened: 2026-07-13
• Main already has: PlatformTrustConfig with allow_all_users/allowed_users only; adapter construction via inline env-var logic in from_env() and serve().
• Net-new value: Full credential/connection config (sa_key_json, sa_key_file, access_token, audience, webhook_path, enabled) with config-first resolution, DRY adapter construction, dedicated docs section.

5️⃣ Three Reasons We Might Not Need This PR

1. Env vars work fine today — Google Chat deployments already configure everything via GOOGLE_CHAT_* env vars; the config file is optional. Counter: config-first is the project-wide direction (umbrella: config-first parity — every platform section resolves config → env → default for ALL fields #1375) and enables unified validation/docs.
2. Stacked PR risk — depends on feat(wecom): full [wecom] section — credentials + connection config-first #1382 → feat(line): full [line] section — credentials + connection config-first #1381; merge conflicts if parents change. Counter: stacking is the agreed workflow; net-new diff is isolated to googlechat.
3. Standalone gateway still env-only — serve() doesn't call apply_googlechat_config, so config-first only works in unified mode. Counter: this is by design (documented in Phase 1c consolidation plan); standalone gateway is the legacy path.

[chaodu-agent]

Note

LGTM ✅ — Clean config-first graduation of [googlechat] from trust-only to full platform section.

What This PR Does

Google Chat's credentials and connection settings were env-only; this graduates [googlechat] from the shared PlatformTrustConfig to a dedicated GoogleChatConfig (6 fields + trust), resolving each field config → GOOGLE_CHAT_* env → default.

How It Works

• Core: GoogleChatConfig / ResolvedGoogleChat + resolve() method; trust_config() view preserves the registry path unchanged.
• Gateway: Adapter construction deduplicated into GoogleChatAdapter::from_parts (was copy-pasted between from_env and serve()); GatewayGoogleChatConfig bridge + apply_googlechat_config(); googlechat_webhook_path state honored by both binaries.
• Unified: Applies [googlechat] before warn_unenforceable_l1 so config-supplied audience satisfies L1 without false warnings.
• Docs: config-reference (dedicated section), google-chat.md updated, config.toml.example annotated.

Findings

#	Severity	Finding	Location
1	🟢	Follows the established LINE/WeCom graduation pattern exactly — consistent layering	config.rs, lib.rs, main.rs
2	🟢	DRY deduplication of adapter construction removes ~30 lines of copy-paste	googlechat.rs:273
3	🟢	Empty-string fallthrough for ${} expansion correctly handled	config.rs opt_str closure
4	🟢	Ordering discipline: apply_googlechat_config before L1 audit prevents false warnings	main.rs
5	🟢	Comprehensive test: defaults, config-wins, empty-string fallthrough, trust_config(), L1 integration	config.rs, lib.rs

What's Good (🟢)

• Resolution pattern (config → env → default) is identical to LINE and WeCom — makes the codebase predictable.
• trust_config() view method lets the shared registry path continue working unchanged during the transition.
• GatewayGoogleChatConfig bridge type keeps the gateway crate free of openab-core dependency.
• Test env cleanup is thorough — no global state leakage between scenarios.
• #[cfg(not(feature = "googlechat"))] fallback for googlechat_webhook_path ensures compilation without the feature flag.

Baseline Check

• PR opened: 2026-07-12 (stacked on feat(wecom): full [wecom] section — credentials + connection config-first #1382 → feat(line): full [line] section — credentials + connection config-first #1381 → main)
• Main already has: [googlechat] as Option<PlatformTrustConfig> (trust-only: allow_all_users + allowed_users)
• Net-new value: Full credentials/connection config (6 fields), resolve() with env fallback, adapter DRY construction, webhook_path in AppState, dedicated docs section

5️⃣ Three Reasons We Might Not Need This PR

1. Standalone gateway mode unchanged — The serve() path still reads all Google Chat settings from env only; config-first benefits only apply to unified mode today. However, this is by design (gateway has no config.toml) and consistent with LINE/WeCom.
2. Google Chat is likely the least-deployed adapter — Investment in config ergonomics might not match usage. Counter: the config-first contract (umbrella: config-first parity — every platform section resolves config → env → default for ALL fields #1375) applies uniformly to all platforms.
3. Stacked PR complexity — Depends on feat(wecom): full [wecom] section — credentials + connection config-first #1382/feat(line): full [line] section — credentials + connection config-first #1381; merge conflicts possible if parents change. Counter: the net-new diff is isolated to the last commit and the rebase plan is documented.