omp-antigravity-acp-provider

Google Antigravity's official ACP server, adapted for Oh My Pi (OMP).

An OMP-focused derivative fork of zacbemis/pi-antigravity-acp-provider. Original project by zacbemis and contributors, licensed under MIT.

This is an independent adaptation, not an official Google or OMP integration. It uses ACP over stdio. The local HTTP MCP bridge carries tool calls; it is not a model API reverse proxy.

Upstream and fork scope

The original project's ACP transport, Google-managed authentication, runtime installation, session restoration and MCP tool bridge form the foundation of this project. Credit for those capabilities belongs to the upstream authors.

This derivative adds OMP-specific provider registration, confirmed model/thinking selectors, lazy catalog loading, OMP-first tool instructions, API-equivalent pricing and per-session runtime lifecycle fixes for planning/refinement.

The repository vendors the upstream 0.1.15 source under extension/vendor/pi-antigravity-acp-provider (MIT, see extension/vendor/pi-antigravity-acp-provider/LICENSE). The standalone artifact bundles its runtime code, supervisor and signed runtime manifest; end users need no production npm dependencies. It does not contain a copy of upstream's Git history. See THIRD_PARTY_NOTICES.md for the original copyright and license notice.

Status

Version 0.1.26 waits for ACP process exit during session lease handoff and isolates idle runtimes while keeping the 0.1.24 session-ownership and profile-isolation fixes. Restart all OMP processes after upgrading so they participate in session ownership.

Version 0.1.26 supports all models advertised by the official ACP server. Earlier live inference was tested with macOS, OMP 18.12.5, upstream provider 0.1.15 and official ACP runtime 1.4.1. The 0.1.21–0.1.24 continuity fixes are verified offline, including OMP 18.13.3 catalog loading and the local OMP summarizer source. Other platforms and full interactive Refine plan behavior with a real model remain unverified.

Google's consumer-plan policies can restrict third-party agent access even through the official CLI or ACP executable. An official transport does not establish permission to use a subscription in OMP. Check the current Antigravity FAQ and terms for your account.

Features

• All server-advertised model IDs, without a Gemini-only whitelist. Claude, GPT-OSS or future models become available when the ACP endpoint advertises them for your account.
• Per-model, server-confirmed thinking selection. OMP efforts off, minimal, low, medium, high, xhigh and max are exposed only when advertised; models without these choices use the server default.
• Compatible OMP tools exposed through an authenticated loopback MCP bridge.
• Provider-specific instructions prefer OMP tools and require approval before substituting native Antigravity tools. Supported runtimes receive these instructions through the official system-append extension and eagerly register the pi-bridge tools.
• Optional native built-in tool filtering; default prefer mode keeps native tools available, while disabled mode removes native built-ins for this adapter's ACP sessions.
• Duplicate gray ACP tool-status lines are hidden by default, with an optional debug display switch. OMP tool calls/results and actual thought summaries remain visible.
• Lazy ACP startup; model selection and cached listing do not launch the server.
• Runtimes scoped to OMP sessions, including recovery after a planning session is disposed.
• OMP /login support plus /antigravity-acp login, logout and account commands; OMP's /logout automatically finishes the Antigravity-side logout, including the macOS keychain entry the Antigravity server owns.
• API-equivalent cost estimates, not subscription billing or quota measurements.

Install from the OMP marketplace

No server is needed: this GitHub repository is also an OMP marketplace named sencha-plugins.

Add the source once, then install the plugin:

omp plugin marketplace add SenCha930511/omp-antigravity-acp-provider
omp plugin install omp-antigravity-acp-provider@sencha-plugins

Or, inside OMP:

/marketplace add SenCha930511/omp-antigravity-acp-provider
/marketplace

Select omp-antigravity-acp-provider in the browser, install it, and restart OMP to load the provider.

OMP's marketplace installer currently copies Git content without installing npm dependencies. This marketplace therefore ships a small source launcher that retrieves the exact published 0.1.26 prebuilt npm adapter on first load. It disables npm install scripts and performs no local compilation. Node.js 22.19+ and npm must be on PATH. The standalone build bundles the required code and supervisor assets with no production dependencies: a clean test installation occupied approximately 2.6 MiB (477 KiB tarball), down from roughly 150 MiB with the old dependency tree. This excludes the separately downloaded Google runtime. First preparation needs internet access; later loads reuse the installed cache without npm network access.

The launcher stores its versioned dependencies in .runtime/ inside the installed marketplace plugin's cache directory. Uninstalling the marketplace plugin removes that cache when it is no longer referenced by another scope. Google credentials and the separately downloaded official ACP runtime are unaffected.

Use either marketplace installation or direct npm installation for this provider. Disable/remove an existing installation before switching to avoid duplicate provider registration. Adding this source makes it available to users who add sencha-plugins; it does not submit the package to a central curated store.

To refresh the catalog and upgrade an existing marketplace installation:

omp plugin marketplace update sencha-plugins
omp plugin upgrade omp-antigravity-acp-provider@sencha-plugins

Install directly from npm

The prebuilt package is published on npm as omp-antigravity-acp-provider. Use Node.js 22.19 or newer and OMP to install the latest release:

omp plugin install npm:omp-antigravity-acp-provider

To pin a specific release:

omp plugin install npm:omp-antigravity-acp-provider@0.1.26

Restart OMP after installation. The npm package includes the built adapter; users do not need esbuild or a manual build step. Disable any older ACP adapter for the same provider before loading this package.

The standalone npm package has no production dependencies or Pi CLI peers. Source development uses the pinned upstream build dependency and this repository's .npmrc.

Find it with zmarketplace

zmarketplace searches npm using ecosystem keywords; it has no separate submission catalog. This package includes the pi-package keyword used for both Pi and OMP discovery, plus extension and plugin resource tags. These discovery tags do not establish compatibility with untested agent runtimes; this adapter targets OMP.

With zmarketplace already installed in OMP:

/zmarketplace search omp-antigravity-acp-provider --eco=omp --type=extension

Or search from a terminal with Bun:

bunx zmarketplace search omp-antigravity-acp-provider --eco=omp --type=extension

Use the OMP installation target when installing from the search result. The direct OMP command is omp plugin install npm:omp-antigravity-acp-provider. Newly published metadata may take time to appear in npm search results.

Build from source

Use Node.js 22.19 or newer and OMP. Node.js is also required by the upstream process supervisor.

git clone https://github.com/SenCha930511/omp-antigravity-acp-provider.git
cd omp-antigravity-acp-provider
npm ci
npm run check

The checked-in npm configuration disables automatic peer installation because the upstream package declares Pi-specific peers. This adapter explicitly supplies its runtime dependency on pi-ai; it does not need the Pi coding-agent CLI.

The build produces extension/runtime.mjs, extension/assets/ and THIRD_PARTY_LICENSES.txt. They are ignored by Git, rebuilt locally and included in published npm tarballs. Supervisor and runtime catalog paths resolve against these bundled assets, so the bundle does not embed the developer's home directory.

For a temporary session, from this repository:

omp --no-extensions -e ./extension/index.ts

This disables other extension discovery for that invocation, avoiding duplicate registration of an existing ACP adapter. For normal installation, use OMP's extension configuration or point ~/.omp/agent/extensions/omp-antigravity-acp-provider at the built extension directory. Disable any previous antigravity-acp-omp or upstream Pi extension first; do not load two adapters for the same provider.

This repository does not change an existing OMP installation or overwrite its settings.

Sign in and choose a model

1. Run /login and select Google Antigravity (ACP).
2. Complete Google's authorization flow. On headless machines the upstream provider can relay a browser callback.
3. Run /antigravity-acp refresh to discover the models actually advertised for the account.
4. Select a model with /model and use OMP's thinking control to select a supported effort.

/antigravity-acp login runs the same Google authorization through a command dialog without touching OMP's stored account record; use it to re-authenticate or switch the Antigravity-side Google account. /antigravity-acp account shows the current authentication state on both sides.

Both login paths always start a fresh Google sign-in: stored Antigravity credentials are cleared first, so the Google account chooser is always offered and a saved login cannot silently keep the previous account. The Google browser session itself is outside this adapter's control; pick the intended account (or "Use another account") on Google's consent screen.

First use or login may download the official runtime. The observed macOS runtime occupies about 383 MiB; size varies by platform/version. It lives outside this repository under ~/.local/opt/agy-acp/. Do not remove it while ACP processes are running.

If OMP's enabledModels whitelist is configured, add antigravity-acp/* alongside your existing entries in ~/.omp/agent/config.yml to allow newly discovered models. Use individual antigravity-acp/<server-model-id> entries instead if you prefer a restricted list. The adapter does not rewrite that whitelist or any model-role preset.

After upgrading from an older adapter, run /antigravity-acp refresh once to replace the old cached list with per-model selector choices. Startup and ordinary catalog listing remain offline, so new server models appear after an explicit refresh. Availability in the Antigravity app or CLI does not guarantee availability through ACP: on the tested account, ACP still advertised only gemini-4-argon and gemini-3.8-flash on 2026-10-20.

Commands

The initial permission mode follows upstream configuration, whose default is yolo. Native Antigravity tools have separate execution permissions from OMP tools.

Sign out

OMP's oauth contract has no provider-side logout hook, so /logout by itself only removes OMP's stored non-secret marker record. This adapter watches the credential store and finishes the Antigravity-side logout automatically: after /logout removes the marker, it closes this process's ACP runtimes, clears saved ACP session mappings, deletes the local token file and the settings auth choice, and removes the matching macOS keychain entry, then confirms with one line (/antigravity-acp account shows the details). The keychain removal waits for this adapter's ACP server processes to fully exit and verifies the deletion, because a dying server can flush its token back. The cleanup waits for in-flight Antigravity requests to finish, a re-login before it runs cancels it, and automatic credential soft-disables (for example an expired refresh grant) never trigger it. Set OMP_ACP_FOLLOW_LOGOUT=0 before starting OMP to keep OMP's /logout marker-only. /antigravity-acp logout performs the same complete logout in one command without waiting for OMP; it refuses to run while Antigravity requests are active. If its OMP-marker removal is unavailable through the host API, the command says so and OMP's /logout finishes that part.

The provider's non-secret config apiKey fallback is registered only until a logout is observed: removing the marker credential makes the adapter re-register without it in the same tick, so OMP's own logout report finds no remaining "provider config (fallback)" source and the model catalog hides until the next /login. Fresh profiles that never stored a marker keep the fallback so first-run model listing works; storing a marker again restores it.

The debug switch controls gray [Antigravity tool: …] and [Antigravity tool update: …] lines. It defaults to off and applies immediately to this process's active ACP connections. Normal OMP tool displays/results, real thought chunks and plan messages are preserved. The option is saved as debugToolUpdates in omp-tools.json alongside nativeTools; toggling either option preserves the other. Existing policy files without the debug field default to off. Other OMP processes need a restart to read a setting changed elsewhere. OMP_ACP_TRACE=1 is a separate, opt-in terminal diagnostic setting.

OMP tool routing and native-tool mode

By default, prefer mode sends the OMP-first instruction through _meta.antigravity.systemPrompt.append and preloads the pi-bridge tools with eagerMcpServers. These are official runtime extension fields on session new/load/resume, not model API requests. The adapter preserves conversation-level instructions as well. Prompt preference can still be ignored by a model; it does not enforce a tool allowlist.

Eager loading supplies tool schemas up front, which can increase initial prompt size compared with lazy discovery.

For strict native built-in filtering, run /antigravity-acp native-tools disabled. This sets enabledTools: [] in the session extension while retaining the OMP MCP bridge. Run /antigravity-acp native-tools prefer to restore native tool availability. The command closes this process's ACP runtimes; the next request recreates/restores them with the selected policy. Switching back explicitly clears the saved server filter, including on restored sessions.

The setting is stored separately in ~/.omp/agent/antigravity-acp-provider/omp-tools.json as {"nativeTools":"prefer"} or {"nativeTools":"disabled"}. It applies to this adapter and does not configure other providers. Other already-running OMP processes need to restart to pick up a change. Native filtering does not remove separately configured global MCP servers and is not a filesystem sandbox. Unsupported or omitted OMP tool schemas remain unavailable; disabled mode cannot substitute native tools for them.

Advanced routing requires the official antigravity-acp 1.x server, version 1.4.1 or newer, advertising system-append support in its agent capabilities. On an incompatible server, prefer falls back to the conversation-level prompt; disabled rejects session creation/restoration rather than silently allowing native tools. /antigravity-acp status shows the selected mode and whether active connections use system append or the legacy prompt channel. Live behavior has been verified on server 1.4.1.

Data locations

Never include those user data directories, OAuth callback URLs, account identifiers or downloaded runtime binaries in issues or commits. OMP_ACP_TRACE=1 enables opt-in tool/selector diagnostics; review diagnostic output before sharing.

Context continuity and local performance

Each runtime also keeps bounded, value-validated system-message and tool-definition snapshots. Equivalent new containers reuse the existing canonical fingerprint/tool projection fingerprint; every selected field is still checked, including in-place schema edits and non-enumerable schema properties. Unsupported shapes fall back to the original algorithm. Each of the two caches holds one entry, capped at 32,768 value nodes, 131,072 primitive snapshot items and 2,097,152 UTF-16 code units in keys/string values; these are local snapshot limits, not model tokens or context limits. Tool execution closures are not retained, and runtime teardown clears the caches.

Session mappings use asynchronous file I/O and nonblocking cross-process lock retries, with ordered read/merge/atomic-rename writes. Each request saves a versioned in-flight marker before dispatch and clears it only with an accepted terminal checkpoint. A failed checkpoint, unknown prompt failure or incomplete tool/permission fallback cannot be trusted as a warm restoration point. Legacy mappings without the marker are reconstructed once from retained OMP history; subsequent clean checkpoints remain resumable. Invalidated turns cannot repersist old mappings, and conditional removal preserves a newer replacement. Local preflight failures retain known-good warm sessions. Cancellation checkpoints are awaited before the turn releases its queue; shutdown waits for active checkpoint writes and rechecks dispatch eligibility afterward. Malformed JSON/non-array registries and I/O failures are reported rather than silently overwritten. Cleanup registry transactions, file scans and deletion also use asynchronous I/O; small command/configuration reads remain synchronous. This does not remove Google's cancellation-confirmation wait. See the continuity invariants, Esc performance implementation and measurements and resource-management notes.

History comparisons reuse SHA-256 digests for unchanged large, simple messages. Every lookup validates the selected live fields against an independent snapshot, including nested tool arguments and in-place text edits; object identity alone never establishes a match. Small messages (below 2,048 characters per text/image/thinking string), complex payloads and unsupported objects use the original algorithm. The digest format and all checks after asynchronous work remain unchanged, so saved sessions stay compatible. Weak keys allow snapshots to be reclaimed when OMP drops old messages, including after compaction. This reduces local comparison work; it does not increase Google's cache-hit rate or guarantee faster model generation. See the offline benchmarks and memory measurements.

New user requests supersede an interrupted ACP turn, including pending tool calls and permission prompts. The adapter cancels old waits and sends official session/cancel, then waits up to the existing 1.5-second cancellation deadline for the old turn to settle. A confirmed cancellation (or a clean completion racing with cancellation) keeps the warm ACP session when the transport is alive and the retained OMP history matches. New prompts queue behind that drain and are sent as new requests, never silently treated as old tool-result continuations. Ordinary completed turns and genuine tool continuations also stay warm. Tool/permission continuations claim one owner before asynchronous work; overlapping duplicates receive an explicit error instead of stealing the response stream. Changed or missing completed assistant output forces reconstruction so the backend and OMP-visible histories agree.

The cancellation checkpoint records the accepted message boundary and the partial assistant output fingerprint, including across idle shutdown/resume. If cancellation is unacknowledged, the process fails, the history is edited/compacted, or previously emitted partial output is missing or changed in OMP, the adapter reconstructs from retained history instead. Thus Esc does not always create a new ACP session, but reuse is conditional rather than guaranteed. Cancelled turns skip supplemental /usage queries while retaining any ACP context-occupancy update. History is explicitly separated from the current request after official ACP text conversion; cold tool handoffs resume from completed results rather than restarting prior actions. Preserving a session avoids unnecessary replay but does not guarantee a backend cache hit. See the Flash cancellation/cache research and implementation checks.

Routing uses the provider request's sessionId, independently of shared prompt-cache keys and the UI transcript ID. OMP's provider-state close/release hooks cover /fresh, reset and side-request lifetimes; old deferred requests cannot dispatch after closure, and replacement requests wait for teardown. Duplicate/ambiguous mappings are rebuilt, and a fresh Google login clears previous-account mappings. Concurrent identical input snapshots are rejected instead of dispatched twice; the same text in a distinct later user turn remains valid. Only tool names, descriptions and schemas enter ACP history fingerprints, excluding mutable OMP host objects. See the source review and transition coverage. Run npm run test:omp-sessions for an isolated offline integration with the installed OMP CLI and a fake ACP transport; it creates no Google sessions and performs no inference.

The adapter transfers complete replay history within bounded budgets, including historical image attachments. It does not silently keep only a history tail. The official harness also has a per-step text conversion limit independent of its model window: the inspected configuration limits a step to 64,000 tokens and truncates oversized text to its first 192,000 UTF-8 bytes. A large cold replay after Refine plan can therefore lose the latest question at the tail even when the advertised model window has room. The adapter rejects rendered prompt text above 188,000 bytes before session/prompt, leaving 4,000 bytes for official wrapping/metadata. The context-overflow error lets OMP use its existing compaction/retry flow; OMP's adaptive summary windows can split oversized summary input too. If compaction is disabled or cannot reduce the request, use /compact or reduce the input before retrying. The adapter itself neither summarizes nor adds inference. See step-limit behavior and offline validation.

Token budgets, wire payload size and the per-step text limit are independent. The default wire payload limit is 16 MiB, configurable up to 128 MiB; raising it or contextWindow does not bypass the per-step text guard. Image data additionally defaults to an 8 MiB decoded payload limit and is not counted as rendered text. The automatic input-token budget is contextWindow - maxTokens - reserveTokens, where reserve defaults to the smaller of 16,384 and 5% of the window. A lightweight Unicode-aware estimate checks serialized text plus approximately 4,096 tokens per image. This is not a Gemini tokenizer, cannot guarantee exact token counts and does not include every hidden server instruction.

Persist settings in ~/.omp/agent/antigravity-acp-provider/context.json, or use the commands below. Defaults apply to every ACP model; entries under models override one advertised model ID. Model limits are client metadata and transfer budgets: they do not expand Google's server window or set an unsupported ACP generation-output parameter.

{
  "defaults": {
    "contextWindow": 524288,
    "maxTokens": 32000,
    "reserveTokens": 16384,
    "maxTransferBytes": 16777216,
    "maxImageBytes": 8388608,
    "usageMode": "off"
  },
  "models": {}
}

Numeric keys: contextWindow, maxTokens, reserveTokens, inputTokenBudget, maxTransferBytes, maxImageBytes. Omit inputTokenBudget to calculate it automatically. A custom input budget must fit alongside output and reserve. Settings load once per process, without disk reads on every streamed chunk. Direct file edits require a restart; commands persist settings and refresh registration in the current process. Restart OMP or reselect the model to refresh displayed metadata. Other OMP processes must restart.

/antigravity-acp context
/antigravity-acp context set default maxTransferBytes 33554432
/antigravity-acp context set gemini-4-argon contextWindow 1000000
/antigravity-acp usage off
/antigravity-acp usage auto

For OMP-managed automatic compaction, keep compaction.enabled, compaction.midTurnEnabled and compaction.autoContinue enabled with a working method such as soft. A provider-specific threshold can be set without changing other providers:

omp config set compaction.modelThresholds '{"antigravity-acp/*":"85%"}'

Merge that map with existing model-specific entries before running the command. At the example 524,288-token window, 85% triggers at 445,644 tokens, below the automatic transfer estimate budget of 475,904 tokens. OMP can also recover from local context/payload overflow errors. Google independently controls its internal agent summaries. Plugin installation does not automatically change OMP's global compaction configuration.

Active sessions are reused. After five idle minutes, the adapter closes its ACP runtime, bridge and child processes; the next request tries to restore the saved server session. It also keeps at most two idle runtimes per OMP process by default, evicting the least recently used idle entry when necessary. Active streams, outstanding ACP prompts, tools and permission waits prevent eviction. Process eviction preserves mapped session files. No background model prewarming, quota polling or tokenizer model download is performed.

Local ACP session cleanup

Session-file deletion is separate from the five-minute idle process shutdown. Configure one of four modes:

/antigravity-acp cleanup
/antigravity-acp cleanup off
/antigravity-acp cleanup conservative
/antigravity-acp cleanup balanced
/antigravity-acp cleanup timeout 7
/antigravity-acp cleanup budget 50 512

Settings persist in ~/.omp/agent/antigravity-acp-provider/cleanup.json:

{ "mode": "conservative", "idleDays": 7, "maxSessions": 0, "maxBytes": 0, "orphanGraceDays": 1, "batchSize": 8 }

The optional budgets default to disabled (0); the command accepts MiB and saves bytes. cleanup balanced sets missing budgets to 50 sessions and 512 MiB, resets ordinary orphan retention to 7 days (or the supplied DAYS), and supplies a 1-day orphan grace and recovery window. Existing explicit budgets, including disabled (0) limits, are preserved. The default remains conservative; installing an update does not switch an existing policy.

For example, the balanced preset without prior overrides saves:

{ "mode": "balanced", "idleDays": 7, "maxSessions": 50, "maxBytes": 536870912, "orphanGraceDays": 1, "recoveryDays": 1 }

Size accounting uses logical file sizes rather than allocated APFS space. In off and conservative, exceeding a budget only produces a status warning. In timeout and balanced, budget eviction uses least-recent activity among unmapped, unleased owned sessions after orphanGraceDays (default 1 day, range 1 hour–3650 days). Mapped and active sessions can keep usage above the budget. The balanced recovery window cannot be bypassed by either quota pressure or ordinary idle expiry; recoveryDays accepts 1 hour–3650 days. Explicitly deleted OMP journals retain their separate deletion-confirmation rules.

Commands take effect immediately; direct file edits are read on the next cleanup check. Checks run when the cleanup service starts, after replacement/release, on the inspection command, and every 15 minutes while the service is running. Replacement/release persists bookkeeping before scheduling file cleanup in the background. Each batch removes at most batchSize sessions (default 8, range 1–100); eligible overflow schedules another batch after one second. OMP must be running for timed checks; the deadline is not an exact scheduled deletion time. No additional model requests, tokenizer downloads or background worker processes are used.

Only sessions created and registered by this adapter version onward are eligible. Pre-existing/unidentified ACP sessions are preserved. All cleanup modes protect IDs in saved sessions.json mappings. The registry is separated by the resolved ACP storage root, and tracks both OMP and ACP supervisor PIDs across participating processes. Resume/load acquires a lease before replay; the cross-process lease lock remains held during asynchronous deletion. Busy/corrupt registries, malformed mappings and unsafe paths defer deletion. Failed lifecycle updates remain in a bounded in-memory retry queue (1024 entries) until the next successful transaction; a process crash can lose queued intentions, so deletion is never guaranteed. The status shows mapped/unmapped/active counts, logical bytes, bytes reclaimed in the latest batch, copies retained for recovery, deferred work, failures and pending updates. Restart older OMP instances when upgrading: clients that do not implement these leases, or external clients manually opening the same session, are outside this coordination mechanism.

OMP explicitly releases routing IDs for final one-shot side requests. After runtime teardown, the adapter persists a disposable marker and conditionally removes only that request's matching owned mapping; newer, duplicated or shared mappings are preserved. A reused routing ID waits for this cleanup before dispatch. This also works after idle runtime eviction. If a process exits between marking and unmapping, later collection repairs the interruption; restoration refuses a finally released ACP ID. Generic provider close, process shutdown, switching sessions, and reusable side conversations do not mark their mappings disposable. Balanced mode retains the released ACP files as a temporary recovery copy; it does not add them to OMP history or expose a recovery UI.

Cleanup targets only the registered UUID's .db, SQLite journal/WAL/SHM files, .meta, and brain/<UUID> directory under the ACP storage root (normally ~/.gemini/antigravity-acp/; respects GEMINI_HOME). Symlinked targets are preserved. Credentials, global settings, shared artifacts, workspace files and OMP's own conversation history are untouched. Local deletion is permanent and does not request deletion of Google's server-side logs. The current official ACP runtime does not advertise session deletion, so this uses the inspected local layout rather than an unsupported RPC.

Timeout and balanced cleanup sacrifice ACP-only reasoning/checkpoint state for eligible unmapped sessions. If that session is later requested through another history source, the adapter reconstructs it from OMP's retained history and can incur replay latency and a different token count. Cache expiry is not assumed or guaranteed. Ordinary mapped conversations remain resumable in every mode; budgets cannot bound the number of mapped OMP conversations you keep.

Deleting an OMP conversation

Version 0.1.20 can reconcile deleted OMP journal files with their ACP mappings. On session_start, session_switch and agent_end, it records the file path only after reading a matching OMP session header and finding an adapter-owned ACP mapping. It supports the managed sessions/ root beside the provider state directory, including named profiles. Custom/external storage and old mappings without a verified source remain protected until supported or observed again; merely installing the build does not identify every old mapping.

With conservative or timeout, a tracked source must be absent on two cleanup checks at least 60 seconds apart, have no live ACP leases, and remain absent after a bounded search of the managed journal buckets for the same header ID. Moving/renaming a journal within those buckets updates its path. Missing/replaced storage roots, symlinks, malformed headers, permission errors and scan limits preserve data. Only then does cleanup conditionally remove the matching mapping and make the owned ACP session eligible for the existing deletion batches. Newer mappings are protected by the mapping store's lock. Turning cleanup off preserves both mapping and files.

This is eventual reconciliation, not a synchronous OMP delete callback. OMP must be running; periodic checks are 15 minutes apart, so idle detection commonly needs two checks (up to roughly 30 minutes after deletion). The cleanup command can trigger checks manually, but cannot bypass the one-minute confirmation interval or live leases. Closing, switching or archiving a conversation leaves its journal intact and does not request deletion. There are no model calls or continuous transcript watchers. Normal checks inspect tracked paths; relocation scans run only for missing sources and are shared within one sweep, bounded to 20,000 entries, four directory levels and 64 KiB per journal prefix.

Optional timing diagnostics

Use /antigravity-acp diagnostics on, then /antigravity-acp diagnostics to inspect timings for history/tool comparisons, session initialization/restoration, checkpoint writes, prompt/first-output and cancellation confirmation. /antigravity-acp diagnostics reset clears samples; off disables collection and clears them. This is separate from the tool-status debug switch.

Collection defaults to off and retains at most 128 samples in memory. Only the enabled flag persists in diagnostics.json; samples contain stage names and durations, without request content, account identifiers or session IDs. It sends no model/usage requests. Prompt timings include Google processing and tools, and are not a measure of local comparison cost alone.

Optional environment settings, applied when OMP starts:

When automatic usage is enabled and /usage is advertised by the official server, the adapter queries it after each completed ACP prompt and computes a difference from the previous cumulative snapshot. A restored session first establishes a baseline so its old tokens are not charged again. These are main-agent totals and can include multiple internal model calls. Thinking tokens count toward estimated output cost. Queries are bounded by a five-second deadline; unavailable/malformed usage or a counter reset does not turn a successful model answer into a billing claim. Native ACP response usage takes priority when supplied. Query failures can cancel/retire the connection; subsequent work can restore the server session.

Supplemental queries default to auto for compatibility; the example above opts out. Use /antigravity-acp usage off to reduce the delay between the last text chunk and OMP regaining control, or auto to retain available token/cache/cost estimates. In a Flash Low test with three turns per mode, that final delay had a median of 282 ms with auto vs 21 ms with off (261 ms less). Individual queries took 241–580 ms. This small sample does not establish a universal speedup, and total response time also varies with inference. Turning queries off preserves ACP context-occupancy updates used by OMP compaction; missing accounting data stays unavailable.

ACP usage_update.used is passed to OMP separately as usage.contextTokens, rather than treating aggregate billable consumption as context occupancy. OMP 18.12.3 recognizes this field; it can still use a local stored-history estimate when deciding whether to compact. Google continues to control its own internal summaries.

Stable tool ordering and stable context-resource identifiers avoid unnecessary client-side prefix changes. They do not guarantee implicit cache hits. /antigravity-acp usage marks cache information as unknown when Google omits it; zero cache fields in OMP's numeric usage structure must not be read as proof of zero backend caching. If cache counts are missing, the API-equivalent estimate prices input as uncached and cannot reflect any unreported cache discount. This is not a subscription bill or a measurement of quota deduction.

See the 0.1.8 context/compaction and usage benchmark for current settings and measurements. The 0.1.7 report documents the previous implementation.

Limitations

• Argon/Flash default to client metadata of 1,000,000 context tokens and 65,536 output tokens. These can be overridden in context.json. Other models use conservative defaults of 32,768 context tokens and 8,192 output tokens because the model selector does not supply these limits. These are client metadata, not verified server limits or controls over Antigravity's internal compaction.
• API background execution and long decode controls are not exposed.
• The bridge advertises text and image input, not the full Gemini API media surface.
• Thought summaries appear only if the ACP server emits them. A verified Argon High request returned no agent_thought_chunk; plan progress and optional debug tool-status lines can appear in OMP's thinking area.
• Cached-token usage appears only when ACP reports it. Missing counts are not proof that backend caching was disabled.
• The prompt inactivity watchdog is 10 minutes without progress, or 60 minutes while tools/permissions are outstanding.
• Argon estimates use the undiscounted list price: $4 input, $20 output and $0.20 cached input per million tokens. Flash estimates use the announced date-dependent rates. These are snapshots, not live pricing discovery.
• Other models have no configured API price yet. Their zero cost fields are placeholders for unavailable estimates and do not mean free usage.
• Not every OMP tool schema is bridge-compatible. Inspect tools after a request.
• Antigravity still manages its own native tools and checkpoint summaries.

Development and verification

npm test runs offline regression tests for all-vendor catalogs, per-model thinking choices, selector routing, session ownership, restart-after-shutdown, asynchronous teardown and price calculations. It performs no model inference and consumes no account quota.

npm run test:omp-compaction additionally requires OMP_ACP_TEST_OMP_SOURCE pointing to an OMP source checkout with built dependencies. An optional OMP_ACP_TEST_NATIVE_ADDON can point to an installed OMP native addon when the checkout has no built addon. It runs OMP's real adaptive summary-window algorithm with synthetic completions, verifies that all history windows are visited, and checks that a compacted plan refinement retains the newest question. It performs no inference and does not modify the OMP checkout.

npm run test:usage uses Bun and mocked protocol responses to verify restored-session baselines, counter resets, query failures and advertised-command gating without starting ACP. bun scripts/verify-continuity-live.ts --live is a separate Flash-only probe of long history, synthetic tools, usage accounting and idle process reclamation/restoration; it consumes quota. Its one-second idle setting is isolated to the test process and is not the production default.

npm run test:auth uses Bun with an isolated GEMINI_HOME, a stubbed keychain and a stubbed OAuth flow to verify the account view (including Google-account email extraction from the stored id_token), login dialog mapping, logout cleanup, the active-request guard and the credential-store watch behind OMP-logout following (removal, automatic-disable suppression, re-login cancellation, opt-out and busy deferral) without starting ACP. Real Google login and logout change account state, so they are not part of any automated test.

npm run test:packed additionally requires OMP on PATH. It installs the exact npm tarball into a temporary consumer directory with development dependencies omitted and install scripts disabled, checks the standalone assets and supervisor, verifies there are no production dependencies, measures package size, and loads its model catalog with ACP execution disabled. It removes the temporary installation afterward.

npm run test:marketplace exercises catalog discovery, installation, automatic provider loading, offline cache reuse and uninstallation in a temporary named OMP profile. It downloads the published adapter and cleans the entire test profile afterward. Add -- --remote after publishing catalog changes to test the GitHub source instead of the local working tree. No model inference is performed.

bun scripts/verify-session-routing-live.ts --live tests synthetic read/edit/command tool round trips, cold ACP session restoration, model changes, and both directions of native-tool mode switching. It consumes quota and creates server history, but does not execute real commands or edit workspace files. Temporary client session mappings are removed afterward.

npm run test:commands requires Bun and exercises command persistence and validation offline with an explicitly isolated state directory. The 0.1.4 live routing check passed both prefer → disabled and disabled → prefer on cold session resume, including an Argon-to-Flash model change; all observed task tools were pi_read, pi_edit and pi_bash.

bun scripts/verify-debug-live.ts --live explicitly tests default-off, on and off again on the same ACP session, using an isolated policy and a synthetic read tool. It checks that tool calls/results and a clearly marked synthetic thought event still reach OMP while debug status visibility follows the switch. It consumes quota and creates server history.

For an explicit live check of outgoing tool-priority instructions, incoming thought events and a synthetic OMP tool round trip, use bun scripts/diagnose-observability.ts --live --installed from this source checkout. It consumes quota and creates ACP sessions. See the 2026-10-20 verification report, including the corrected diagnosis of an isolated prompt-precedence test.

Before publishing, verify local OMP loading without allowing ACP to start:

AGY_ACP_BIN=/usr/bin/false omp models antigravity-acp --no-extensions -e ./extension/index.ts --json

With no local model cache, upstream's conservative fallback may list fewer models. Listing a model is not proof of account entitlement or successful inference.

The original local implementation also passed live Argon/Flash inference, effort-selector and OMP tool round-trip checks. The planning lifecycle fix passed a live Argon Medium request, session shutdown and a subsequent request with conversation history. Those tests do not cover every platform or the complete interactive Refine plan UI.

The generic catalog implementation passed a live refresh and Argon Low/High inference. Claude, GPT-OSS and future IDs are covered by offline catalog/selector fixtures; live inference for those models remains unverified until the ACP server advertises them.

MIT. See LICENSE and THIRD_PARTY_NOTICES.md. Upstream source is vendored under extension/vendor/pi-antigravity-acp-provider (MIT) and kept with attribution. Official Google executables and their licenses are separate.