Docs: refresh TTS backend policy status

docs/.internal/extension-host-migration/openclaw-capability-catalog-and-arbitration-spec.md

@@ -618,7 +618,7 @@ Capability selection must emit structured events for:
 - channel capabilities from `extensions/discord/src/channel.ts:74`, `extensions/slack/src/channel.ts:107`, and `extensions/telegram/src/channel.ts:120` collapse into canonical messaging action families
 - diffs becomes an agent-visible tool family plus a host-managed route surface from `extensions/diffs/index.ts:27`
 - provider integration from `extensions/google-gemini-cli-auth/index.ts:24` becomes operator-visible setup and auth capabilities
-- catalog-backed runtime-family descriptors for embeddings, media, and TTS now route through `src/extension-host/runtime-backend-catalog.ts`; embedding shared backend definitions in `src/extension-host/embedding-runtime-backends.ts`, media shared backend definitions in `src/extension-host/media-runtime-backends.ts`, TTS shared backend definitions in `src/extension-host/tts-runtime-backends.ts`, and initial runtime-family arbitration in `src/extension-host/runtime-backend-arbitration.ts`; embedding auto-provider selection, embedding local setup guidance, memory doctor guidance for embedding auto-provider order, media auto-selection and default-model lookup, and TTS request setup, status, and compatibility provider-order exports already consume that catalog-backed arbitration data, and broader consumer adoption and arbitration should continue moving those subsystem runtimes toward runtime-internal registries rather than leaving them as a universal plugin-provider API shape
+- catalog-backed runtime-family descriptors for embeddings, media, and TTS now route through `src/extension-host/runtime-backend-catalog.ts`; embedding shared backend definitions in `src/extension-host/embedding-runtime-backends.ts`, media shared backend definitions in `src/extension-host/media-runtime-backends.ts`, TTS shared backend definitions in `src/extension-host/tts-runtime-backends.ts`, and initial runtime-family arbitration in `src/extension-host/runtime-backend-arbitration.ts`; embedding auto-provider selection, embedding local setup guidance, memory doctor guidance for embedding auto-provider order, media auto-selection and default-model lookup, and TTS request setup, status, compatibility provider-order exports, plus explicit TTS configured-fallback policy in `src/extension-host/tts-runtime-policy.ts` already consume that catalog-backed arbitration data, and broader consumer adoption and arbitration should continue moving those subsystem runtimes toward runtime-internal registries rather than leaving them as a universal plugin-provider API shape
 - extension-backed web search should become an agent-visible tool family unless it is only a runtime-internal backend feeding another host-owned surface
 - voice-call from `extensions/voice-call/index.ts:230` becomes a mix of agent-visible actions, runtime providers, and operator surfaces
 - ACP backend registration from `extensions/acpx/src/service.ts:55` becomes runtime-internal backend arbitration

docs/.internal/extension-host-migration/openclaw-extension-host-implementation-guide.md

@@ -272,6 +272,7 @@ Committed implementation slices so far:
 - `4b1f31f947` `Media: share runtime backend definitions`
 - `7ff79aa494` `Memory: adopt embedding backend catalog`
 - `c674dc50a7` `Runtime: add backend-family arbitration`
+- `1b87cdeca1` `TTS: add backend fallback policy`
 - `89414ed857` `Docs: track extension host migration internally`
 - `d8af1eceaf` `Docs: refresh extension host migration status`
 
@@ -291,7 +292,7 @@ Recent plan refinements:
 - it now explicitly treats interactive callback routing, namespace ownership, dedupe, and fallback behavior as first-class migration surfaces
 - it now explicitly treats inbound claim as a canonical ingress-stage concern rather than a permanent plugin-era hook shape
 - it now explicitly treats Telegram and Discord as the first validated rollout targets for interactive control surfaces while keeping the underlying contracts generic, host-owned, and kernel-agnostic
-- it now explicitly treats embeddings, media understanding, and TTS as in-progress host-owned subsystem runtimes, with embedding backend definitions now shared between `src/extension-host/embedding-runtime-backends.ts`, `src/extension-host/embedding-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, embedding selection, fallback routing, public runtime surface, result typing, manager-side batch and fallback policy, sync plus reindex planning, sync plus reindex orchestration, reindex sync-body execution plus unsafe reset, safe-reindex temp-db creation, file swap, reopen, and cleanup, plus runtime-backend catalog descriptors now extracted and embedding auto-provider selection, local setup guidance, and memory doctor guidance already consuming the catalog-backed embedding auto-provider order, media backend definitions now shared between `src/extension-host/media-runtime-backends.ts`, `src/extension-host/media-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, with media registry, execution, auto-entry selection, active-model fallback, orchestration, planning helpers, remaining API composition, lazy entrypoint wiring, plus runtime-backend catalog descriptors now extracted and media auto-selection plus media default-model lookup already consuming that catalog order, TTS backend definitions now shared between `src/extension-host/tts-runtime-backends.ts`, `src/extension-host/tts-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, with TTS registry, execution, request setup, config normalization, preferences, payload planning, shared status state, API composition, plus runtime-backend catalog descriptors now extracted, initial runtime-family arbitration now landing in `src/extension-host/runtime-backend-arbitration.ts`, and TTS request setup, status, plus compatibility provider-order exports already consuming that arbitration-backed catalog order, and broader consumer adoption and arbitration on top of those catalog-backed runtime-family descriptors still pending, all with capability routing, typed request envelopes, provider-id normalization, and fallback policy
+- it now explicitly treats embeddings, media understanding, and TTS as in-progress host-owned subsystem runtimes, with embedding backend definitions now shared between `src/extension-host/embedding-runtime-backends.ts`, `src/extension-host/embedding-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, embedding selection, fallback routing, public runtime surface, result typing, manager-side batch and fallback policy, sync plus reindex planning, sync plus reindex orchestration, reindex sync-body execution plus unsafe reset, safe-reindex temp-db creation, file swap, reopen, and cleanup, plus runtime-backend catalog descriptors now extracted and embedding auto-provider selection, local setup guidance, and memory doctor guidance already consuming the catalog-backed embedding auto-provider order, media backend definitions now shared between `src/extension-host/media-runtime-backends.ts`, `src/extension-host/media-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, with media registry, execution, auto-entry selection, active-model fallback, orchestration, planning helpers, remaining API composition, lazy entrypoint wiring, plus runtime-backend catalog descriptors now extracted and media auto-selection plus media default-model lookup already consuming that catalog order, TTS backend definitions now shared between `src/extension-host/tts-runtime-backends.ts`, `src/extension-host/tts-runtime-registry.ts`, and `src/extension-host/runtime-backend-catalog.ts`, with TTS registry, execution, request setup, config normalization, preferences, payload planning, shared status state, API composition, plus runtime-backend catalog descriptors now extracted, initial runtime-family arbitration now landing in `src/extension-host/runtime-backend-arbitration.ts`, explicit configured-fallback policy now landing in `src/extension-host/tts-runtime-policy.ts`, and TTS request setup, status, plus compatibility provider-order exports already consuming that arbitration-backed catalog order, and broader consumer adoption and arbitration on top of those catalog-backed runtime-family descriptors still pending, all with capability routing, typed request envelopes, provider-id normalization, and fallback policy
 - it now explicitly rejects widening the legacy `registerProvider(...)` or `ProviderPlugin` surface into a universal runtime API while retaining capability routing, typed request envelopes, provider-id normalization, and fallback behavior where those are part of the target model
 - it now explicitly treats extension-backed search as either a canonical tool contribution or a host-owned runtime backend depending on whether the search surface is agent-visible
 

docs/.internal/extension-host-migration/openclaw-extension-host-lifecycle-and-security-spec.md

@@ -147,7 +147,7 @@ What is still pending from this spec:
 - broader extension-host lifecycle ownership beyond the loader state machine, service-lifecycle boundary, CLI-lifecycle boundary, session-owned activation state, and explicit discovery-policy, activation-policy, and finalization-policy outcomes
 - activation pipeline ownership
 - host-owned registries for setup, CLI, routes, services, slots, and backends
-- broader consumer adoption and arbitration on top of the now-started catalog-backed runtime-family descriptors for embeddings, media, and TTS, including explicit fallback and override policy instead of plugin-era capability reads
+- broader consumer adoption and arbitration on top of the now-started catalog-backed runtime-family descriptors for embeddings, media, and TTS, including explicit fallback and override policy instead of plugin-era capability reads; TTS is now the first subsystem family with host-owned configured-fallback policy on top of that arbitration layer
 - a clear host-owned split for extension-backed search between agent-visible tool publication and any optional runtime-internal search backend registry
 - permission-mode enforcement
 - per-extension state ownership and migration

docs/.internal/extension-host-migration/openclaw-kernel-extension-host-transition-plan.md

@@ -258,6 +258,7 @@ Committed implementation slices so far:
 - `4b1f31f947` `Media: share runtime backend definitions`
 - `7ff79aa494` `Memory: adopt embedding backend catalog`
 - `c674dc50a7` `Runtime: add backend-family arbitration`
+- `1b87cdeca1` `TTS: add backend fallback policy`
 - `89414ed857` `Docs: track extension host migration internally`
 - `d8af1eceaf` `Docs: refresh extension host migration status`