feat(protocols): Antigravity direct lane for Messages, on by default

devlog/_plan/260924_protocol_first_class/040_acceptance_and_rollout.md

@@ -50,7 +50,7 @@ branch (`feat/pf12-protocol-rollout`); PF-10 is developed in parallel and is not
 
 | Path | State after this unit |
 |---|---|
-| Chat/Messages request decode | still produces a Responses-shaped body before the IR (`responses-internal`) on every non-native path, with one exception: behind `antigravityDirect`, a Chat request to one concrete Antigravity route decodes straight into the IR (`src/protocols/codecs/chat-ir.ts`, path `chat,ir,other`; see `devlog/_plan/261014_antigravity_direct_protocols/`). Messages decode and every other route still use the named entry points over the existing translators (`chatCompletionsToResponsesBody`, `anthropicToResponsesTranslation`) |
+| Chat/Messages request decode | still produces a Responses-shaped body before the IR (`responses-internal`) on every non-native path, with one exception: under `antigravityDirect` (on by default), a Chat or Messages request to one concrete Antigravity route decodes straight into the IR (`src/protocols/codecs/chat-ir.ts`, `messages-ir.ts`, paths `chat,ir,other` and `messages,ir,other`; see `devlog/_plan/261014_antigravity_direct_protocols/`). Every other route still uses the named entry points over the existing translators (`chatCompletionsToResponsesBody`, `anthropicToResponsesTranslation`) |
 | Chat ↔ Messages direct codecs | not implemented: `chat,ir,messages` and `messages,ir,chat` are baseline targets only; both pairs travel `responses-internal` |
 | Chat/Messages response encode (PF-09) | migrated behind `directEncoders` only where `directEncodersApply` and `clientEncoderForDelivery` both agree: one concrete, non-Responses-wire route in the streaming adapter delivery, giving response path `[upstream, ir, client]` while the request path stays the bridge path. Still through `responses-internal`: combo and policy children (`comboAttempt`, `routeKind` combo/policy), routed compaction, run-turn adapters (Cursor, Devin, coding-agent CLIs, CodeBuddy), sidecar turns, the buffered `parseResponse` branch (unused by these ingresses, which always stream internally), and every route while the switch is off. Responses-wire upstreams keep their existing codec path |
 | Policy-route children | not migrated (PF-07): `routeModel` evaluates the policy and returns one concrete candidate, so a policy request never reaches the combo child loop and keeps the Chat bridge |

devlog/_plan/261014_antigravity_direct_protocols/000_plan.md

@@ -38,11 +38,11 @@ unchanged.
 
 ## Route map (eligible concrete Antigravity route)
 
-| Inbound | Before | After (`antigravityDirect` on) |
+| Inbound | Before | After (`antigravityDirect`, on by default) |
 |---|---|---|
 | Responses | `responses -> ir -> other`, answer `other -> ir -> responses` | unchanged; already direct (`parseRequest`, `bridgeToResponsesSSE`) |
 | Chat | `chat -> responses-internal -> ir -> other`; answer `other -> ir -> responses-internal -> chat` (`other -> ir -> chat` only with `directEncoders`) | `chat -> ir -> other`; answer `other -> ir -> chat` |
-| Messages | `messages -> responses-internal -> ir -> other` | unchanged in this unit (follow-up below) |
+| Messages | `messages -> responses-internal -> ir -> other`; answer `other -> ir -> responses-internal -> messages` (`other -> ir -> messages` only with `directEncoders`) | `messages -> ir -> other`; answer `other -> ir -> messages` |
 
 ## Design
 
@@ -61,10 +61,12 @@ and the end-to-end test requires the same Antigravity wire body on both lanes.
 
 ## Follow-ups
 
-- Messages -> Antigravity direct decode. The Messages ingress applies more bridge-body policy
-  (model resolution, prompt-cache key, blocked-skill elision, cache stabilization, `ocxr1`
-  reasoning envelopes and the native reasoning replay map), so it needs its own parity corpus and
-  decline rules; stack it on this branch.
+- Messages -> Antigravity direct decode: done in the follow-up PR (`messages-ir.ts`,
+  `src/server/messages-antigravity-direct.ts`). The lane is planned before translation on the
+  settings-only body (resolved model, prompt-cache key) against a route preview, reproduces
+  blocked-skill elision, cache stabilization, envelopes and the native replay map, and declines
+  hosted web search, vision preprocessing, the shadow intercept and core-rewritten text. The same
+  PR turns `antigravityDirect` on by default for both lanes; an explicit `false` turns it off.
 - Claude-on-Antigravity thinking continuity: the Google adapter sends assistant thinking parts
   nowhere today; only call-bound `thoughtSignature`s survive. Carrying Claude thinking blocks as
   `thought: true` parts (as CLIProxyAPI does) is an adapter change for both lanes, not part of

docs-site/src/content/docs/guides/protocol-paths.md

@@ -94,15 +94,15 @@ each candidate and skips one that cannot carry the request.
 
 ## Rollout switches
 
-These switches stage the new paths. Each defaults to off, and a switch that is off changes nothing.
+These switches stage the new paths. Each defaults to off except `antigravityDirect`, and a switch that is off changes nothing.
 
 | Switch | When on |
 | --- | --- |
 | `nativeChatCombos` | An eligible Chat candidate inside a combo is sent natively from its own copy of the client body; the other candidates keep the bridge. |
 | `managedMessagesNative` | A Messages request whose route is a direct, key-authenticated Anthropic provider is sent as Messages instead of through the bridge. Routes that need bridge-only behaviour (a pinned effort, blocked-skill elision, the web-search sidecar, vision preprocessing, synthetic rows) stay on the bridge. |
 | `managedMessagesNativeOAuth` | Native Messages for the unpooled `anthropic` OAuth provider on `api.anthropic.com`. Effective only together with `managedMessagesNative`; a pooled Anthropic OAuth account set stays on the bridge. |
 | `directEncoders` | For a non-Responses upstream, the answer to a Chat or Messages client is encoded directly from the adapter's events instead of through the internal Responses stream. The request side is unchanged. |
-| `antigravityDirect` | A Chat request whose route is one Google Antigravity provider skips the internal Responses body in both directions: the conversation is decoded from the Chat body straight into what the Google adapter compiles from, and the answer is encoded directly as with `directEncoders`. The path reads `chat -> ir -> other`. Request settings (model, effort, limits, tool choice) still pass through the usual policies, so account rotation, effort rules and usage are unchanged. Combos, policies, a hosted web-search tool, images for a model marked text-only, and a model the shadow-call intercept could rewrite stay on the bridge, and the log row names the reason. |
+| `antigravityDirect` | **On by default**; set it to `false` to turn it off. A Chat or Messages request whose route is one Google Antigravity provider skips the internal Responses body in both directions: the conversation is decoded from the client body straight into what the Google adapter compiles from, and the answer is encoded directly as with `directEncoders`. The path reads `chat -> ir -> other` or `messages -> ir -> other`. Request settings (model, effort, limits, tool choice) still pass through the usual policies, so account rotation, effort rules and usage are unchanged. Combos, policies, a hosted web-search tool, images for a model marked text-only, a model the shadow-call intercept could rewrite, and text the proxy rewrites (a skills catalog, a generated-image link) stay on the bridge, and the log row names the reason. |
 | `shadowPlan` | At the end of each Chat or Messages request, the plan a preview would have predicted is compared with the path the request took; a disagreement adds `planMismatch: true` to the log row's path record. No second request is sent. |
 
 Change them with the CLI or by editing `protocols` in `config.json`
@@ -133,8 +133,8 @@ does not display it yet.
 These paths still use the internal Responses bridge or are not covered:
 
 - Chat and Messages requests are still decoded into a Responses-shaped body before the IR, including
-  on a translated path. The exception is a Chat request to a single Google Antigravity route with
-  `antigravityDirect` on. Messages requests to Antigravity still use the bridge.
+  on a translated path. The exception is a Chat or Messages request to a single Google Antigravity route,
+  unless `antigravityDirect` is set to `false`.
 - Routing-policy candidates, combos reached through an effort row, combo candidates while
   `nativeChatCombos` is off, and Messages combos.
 - Direct encoding (`directEncoders`) covers only a concrete, non-Responses route in streaming

docs-site/src/content/docs/reference/configuration/server.md

@@ -613,7 +613,7 @@ modes, the preview, and the per-request trace.
 | `protocols.rollout.managedMessagesNative?` | `boolean` | `false` | Send Messages natively to a direct, key-authenticated Anthropic provider instead of through the internal Responses bridge. |
 | `protocols.rollout.managedMessagesNativeOAuth?` | `boolean` | `false` | Native Messages for the `anthropic` OAuth provider on `api.anthropic.com`, including stored account pools. Requires `managedMessagesNative`. For the settled `anthropic` provider, an enabled pool supplies true for absent native flags when `anthropicAccountPool.nativeMessages` is absent or true. Explicit false/malformed flags and a false/malformed pool preference remain off. Other providers and pool-off keep explicit rollout behavior. Eligible pooled requests retain shared selection, affinity and bounded pre-output recovery. Recognized JSON-string `metadata.user_id` account UUIDs are aligned with the serving OAuth credential; device and session fields are preserved. |
 | `protocols.rollout.directEncoders?` | `boolean` | `false` | Encode Chat and Messages answers from a non-Responses upstream directly from adapter events. |
-| `protocols.rollout.antigravityDirect?` | `boolean` | `false` | Send a Chat request to a single Google Antigravity route without the internal Responses body in either direction. Request settings still pass through the usual policies. |
+| `protocols.rollout.antigravityDirect?` | `boolean` | `true` | Send a Chat or Messages request to a single Google Antigravity route without the internal Responses body in either direction. Request settings still pass through the usual policies, and a request the lane cannot carry uses the bridge. Set `false` to turn it off. |
 | `protocols.rollout.shadowPlan?` | `boolean` | `false` | Compare each Chat or Messages request's path with the plan a preview predicts and mark a disagreement as `planMismatch` on its log row. Sends nothing extra. |
 
 Malformed protocol blocks retain a conservative disabled native policy when loaded from disk.

scripts/test-layout/layout.json

@@ -316,6 +316,8 @@
     "protocol-chat-ir-parity.test.ts": "responses",
     "protocol-antigravity-direct-chat.test.ts": "responses",
     "protocol-antigravity-direct-eligibility.test.ts": "responses",
+    "protocol-messages-ir-parity.test.ts": "responses",
+    "protocol-antigravity-direct-messages.test.ts": "responses",
     "chat-native-combo.test.ts": "responses", "jev-initial-effort-wire.test.ts": "responses",
     "messages-native-eligibility.test.ts": "responses",
     "responses-first-send-reservation.test.ts": "responses", "responses-first-send-spend-policy.test.ts": "responses", "responses-dispatch-receipt.test.ts": "responses", "responses-hosted-send-hop.test.ts": "responses", "responses-hosted-send-producer.test.ts": "responses", "responses-hosted-send-reservation.test.ts": "responses", "responses-hosted-send-round-parity.test.ts": "responses", "responses-hosted-send-unsent-hop.test.ts": "responses", "responses-hosted-send-ws.test.ts": "responses",

skills/ocx/references/01_surface_access-remote.md

@@ -330,7 +330,7 @@ State-changing: yes.
 |---|---|---|
 | `--messages` | string | Open or close the Messages API: on or off. Off also turns the Claude integration off. |
 | `--unrepresentable` | string | legacy keeps today's behavior; reject refuses a request its path cannot carry. |
-| `--rollout` | string | One switch as name=on or name=off; repeatable. Every switch defaults off. |
+| `--rollout` | string | One switch as name=on or name=off; repeatable. Every switch defaults off except antigravityDirect. |
 | `--json` | boolean | Emit the resulting GET /api/protocols body. |
 
 JSON mode: `payload`.