coder(providers): v2.3 provider-lifecycle phase 2 — snapshot lifecycle

provider-snapshot no longer returns null for uninstalled/disabled providers: it emits one entry per registered provider with a lifecycle status (loading|ready|unavailable|error), an enabled flag, and a two-tier probe. Tier-1 is a fast which-style check (command-availability.ts, execFile/no-shell); tier-2 (cold ACP probe) is skipped unless forced, last_probed_at is older than PROVIDER_PROBE_TTL_MS (24h), or DB models are empty — the snapshot-latency win. Cache miss returns status:'loading' synchronously while the build settles via the existing inflight promise. ProviderSnapshotStatus/Entry regain loading/unavailable + gain enabled/description?/fetchedAt? in both coder and web copies, guarded by a runtime parity test (provider-types-parity.test.ts; compile-time cross-project check was blocked by TS6307). Also tracks the data/coder-providers.json seed via a .gitignore exception, completing the Phase 1 config file. No dispatch/route/UI changes (Phase 3+); AgentComposerBar filtering unchanged. 13 snapshot tests (+6) + 6 parity tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/coder/src/config.ts

@@ -26,6 +26,10 @@ const ConfigSchema = z.object({
   // v2.3: config-backed provider overrides/custom-ACP entries merged over the
   // hardcoded built-ins. Missing file = built-ins only (see provider-config.ts).
   CODER_PROVIDERS_PATH: z.string().default('/data/coder-providers.json'),
+  // v2.3 phase 2: tier-2 (cold ACP probe) is skipped when available_agents was
+  // probed more recently than this. 24h default — stale model lists self-heal
+  // on the next snapshot; an explicit /refresh always re-probes.
+  PROVIDER_PROBE_TTL_MS: z.coerce.number().int().positive().default(86_400_000),
   // v2.0.5: cheaper model for titles, summaries, labeling.
   FAST_MODEL: z.string().optional(),
   // SSH access to the host for external agent dispatch (Phase 5)