@n1netynine99/omp-antigravity-acp-provider0.1.49

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.

Features

• All server-advertised models, including Claude, GPT-OSS and future IDs when the ACP endpoint advertises them.
• Newest-server auto-selection. When the agy CLI on PATH bundles a newer ACP server than the registry-installed runtime, the adapter launches it through a generated AGY_ACP_BIN wrapper, so CLI-first models appear without manual setup. An explicit AGY_ACP_BIN always wins.
• Per-model thinking levels, exposed only when the server confirms them.
• OMP tools through an authenticated loopback MCP bridge.
• Optional disabled native-tool mode for strict OMP-only sessions.
• Lazy ACP startup and warm session reuse.
• /login plus /antigravity-acp account, usage and cleanup commands.
• API-equivalent cost estimates, not subscription billing.
• Long-running OMP tools survive the MCP request window through a relay. The model resumes the same result with pi_omp_await_result; the control tool is a separate MCP server and never appears in OMP's tool list.
• Permission requests are tied to the originating session, turn and tool call. Forged, conflicting or previous-turn identities fail closed, while normal requests still use OMP's human review.
• The MCP tools/list reflects the current OMP tool set. The offline wire test covers add, remove and restore on one warm ACP session.

Install: for human

Follow these steps in order. The whole flow takes a few minutes, plus Google's sign-in and the first runtime download.

1. Check prerequisites

• OMP is installed and omp --version works.
• Node.js 22.19 or newer (node --version) and npm are on PATH; the marketplace launcher uses them on first load.
• A supported platform: macOS, Linux or Windows. Live testing has been on macOS.
• Internet access for the first run. The official Antigravity runtime downloads separately (about 383 MiB on macOS) into ~/.local/opt/agy-acp/.

2. Install exactly one adapter

Install the published npm package directly:

omp plugin install @n1netynine99/omp-antigravity-acp-provider

Or use the marketplace (this repository is also the sencha-plugins marketplace):

omp plugin marketplace add 00lllooolll00/omp-antigravity-acp-provider
omp plugin install omp-antigravity-acp-provider@sencha-plugins

Do not install both. Remove or disable any older Antigravity ACP adapter first.

3. Restart OMP

The provider registers at startup. Restart every running OMP process so they agree on session ownership.

4. Sign in

Run /login, choose Google Antigravity (ACP), and complete Google's consent in the browser. On a headless machine the provider relays the callback URL.

On Linux the agy CLI stores the OAuth token in the Secret Service keyring (service=gemini, username=antigravity), not in acp_token.json. The adapter reads that item with secret-tool when the token file is absent, so install libsecret-tools (Fedora: libsecret) to make login detection work. /antigravity-acp logout and the follow-up to OMP's /logout clear the same item.

5. Load models and pick one

/antigravity-acp refresh
/model

refresh asks the ACP server which models the account can use; /model lists them. Set an effort with OMP's thinking control when the model advertises levels. If OMP's enabledModels whitelist is configured, add antigravity-acp/* to it.

6. Verify

/antigravity-acp status

This shows the runtime, native-tool mode and usage state. Send a short prompt to confirm inference.

Upgrade and uninstall

Upgrade or uninstall the npm-installed plugin:

omp plugin upgrade @n1netynine99/omp-antigravity-acp-provider
omp plugin uninstall @n1netynine99/omp-antigravity-acp-provider

Troubleshooting

Symptom	Check
omp: command not found	This is an OMP plugin. Install OMP first; there is no standalone CLI.
Google sign-in is requested on every start	The ACP server refreshes its one-hour access token with the saved refresh token at process start. That refresh is cancelled if the process is killed right away, so keep outbound HTTPS to oauth2.googleapis.com reachable (a proxy must be exported as HTTPS_PROXY for OMP, not only set in the desktop environment). /antigravity-acp account shows the stored login; a successful server start logs keyringAuth: loaded token and no token refresh failed line.
No models after /antigravity-acp refresh	Run /antigravity-acp account to confirm both sides are signed in, then retry with internet access. ACP can advertise fewer models than the Antigravity app.
Two Antigravity providers appear	Remove the older adapter (antigravity-acp-omp, the upstream Pi extension, or a duplicate npm install), then restart OMP.
Login opens the wrong Google account	Both login paths always start a fresh sign-in. Choose the intended account (or "Use another account") on Google's consent screen.
disabled native-tool mode rejects the session	The official runtime must advertise system-append support (1.4.1+). Upgrade the runtime or run /antigravity-acp native-tools prefer.
The first request is slow	Runtime download and cold ACP start happen once; later turns reuse the warm session.
A tool call returns a relay notice	The model should call pi_omp_await_result with the notice's call_id. Lower OMP_ACP_TOOL_RELAY_MS or set it to 0 to disable relay.

Install: for agents

The installation runbook is in AGENT_INSTALL.md. Hand that file to an agent with terminal access; it installs and verifies the adapter without starting an interactive login. For example: Read AGENT_INSTALL.md and follow it.

ACP server channels and selection

Google ships the same ACP server through two channels; the adapter picks between them automatically at every OMP startup.

• agy CLI — the self-updating command-line product. When its bundled server is newer than the registry runtime, the adapter launches it through a generated AGY_ACP_BIN wrapper, so CLI-first models (for example Claude and GPT-OSS) appear without manual setup.
• Managed runtime — the registry-signed release downloaded and verified into ~/.local/opt/agy-acp/. Used when the CLI is missing or not newer, and installed automatically when neither channel exists.

Selection order:

1. An explicit AGY_ACP_BIN always wins. Point it at an agy acp-capable executable or wrapper to force a channel.
2. Otherwise the newer server version wins; ties go to the managed runtime.
3. With neither present, the managed runtime is downloaded from Google's registry on next use.

Session storage follows the server's own --app_data_dir. The generated wrapper pins antigravity-acp — the managed runtime's own default — so CLI-launched ACP sessions land in ~/.gemini/antigravity-acp/, where /antigravity-acp cleanup and session ownership tracking operate. Personal agy CLI chats stay in ~/.gemini/antigravity-cli/ and are never read or deleted by the adapter. GEMINI_HOME relocates the managed runtime's tree (upstream behavior); the agy CLI stores under ~/.gemini regardless.

The active channel and its versions are recorded in ~/.omp/agent/antigravity-acp-provider/acp-runtime-source.json whenever the CLI is chosen.

Permission IDs differ between the channels. Managed ACP 1.4.5 supports default, auto_edit, and yolo directly. CLI ACP 1.5.3 advertises default, accept-edits, and plan instead. The adapter maps auto-edit to accept-edits. For yolo, it selects wire mode default and passes the CLI's official --dangerously-skip-permissions flag. This preserves auto-approval instead of substituting accept-edits. Changing permission modes recreates the ACP runtime so a process with auto-approval cannot serve a later default or auto-edit request. An explicit AGY_ACP_BIN is left unchanged.

CLI ACP 1.5.3 omits mcpCapabilities from its initialization response, but it still discovers HTTP MCP servers and calls tools/list. The adapter normalizes this capability for that server identity so OMP tools remain available. CLI 1.5.3 reports no audio input, while the adapter's model catalog already limits input to text and images.

Context occupancy and compaction

ACP may report live occupancy with usage_update. When it does, the adapter forwards that server value. When a runtime (for example CLI ACP 1.5.4) reports only cumulative billable usage, the adapter estimates the full OMP context from the system prompt, retained messages and tool schemas with estimateTransferTokens, then sets usage.contextTokens and marks contextTokensSource: "estimate". The billable input, cacheRead and output counters are left untouched.

The estimate is a heuristic, not a server measurement. Managed ACP remains preferable when exact occupancy matters. In this source checkout, scripts/with-managed-context.sh starts OMP with the installed managed binary while preserving an explicit AGY_ACP_BIN. Run /antigravity-acp refresh afterward to inspect the models that runtime actually advertises.

Keep compaction.autoContinue enabled for normal long-running work. The false context rollover was fixed at the occupancy signal, not by disabling automatic continuation.

Commands

Use the /antigravity-acp prefix once, followed by a row below. For example, status means /antigravity-acp status.

Common operations

Subcommand	Purpose
(none) or status	Show login readiness, negotiated runtime/native channel when available, permission policy, native tools, non-empty usage records and active sessions. Requested and wire permissions share one row when they differ. Empty process details are omitted; runtime/API warnings remain visible.
account	Show the signed-in account, ACP authentication and non-secret OMP marker. Token ownership, logout behavior and account/store inconsistencies are not hidden.
login	Start a fresh Google authorization.
logout	Clear Antigravity credentials, saved sessions and the OMP marker.
quota	Query live quota and print one model heading with one remaining/reset row per quota window. Query failures are reported explicitly.
refresh	Discover and cache advertised models, then list the refreshed IDs.
usage	Show configured → effective supplemental-query mode (OMP_ACP_USAGE=off forces off) and only populated per-connection context, compaction and accounting details.
usage auto	Query supplemental usage after each reply. Context occupancy updates remain enabled.
usage off	Skip supplemental queries without disabling context occupancy updates.

Quota results use a separate short-lived ACP session and a 60-second cache. When the adapter selects a CLI automatically, this read-only query uses managed ACP instead, which supports the quota command. An explicit AGY_ACP_BIN remains authoritative. If that runtime does not advertise usage, the adapter reports the limitation without sending a model prompt. The quota display excludes usage counters for that temporary session.

Advanced maintenance

Subcommand and options	Purpose
tools	Inspect offered/available OMP tools, every omission reason and live MCP capability checks.
context	Show saved shared defaults separately from each cached model's effective limits and model-only overrides. Effective values include the input, output, reserve, transfer and image budgets used by runtime compatibility checks.
context set default KEY NUMBER	Change a shared numeric context setting.
context set MODEL KEY NUMBER	Change one model override. Reselect the model or restart OMP to refresh its displayed limits.
context set default usageMode auto|off	Equivalent to usage auto|off.
cleanup	Collect using the saved policy and show its mode, retention, non-empty session counts, actual removals, warnings and state-loss risk.
cleanup off	Keep every saved session.
cleanup conservative	Remove only eligible idle, unmapped sessions while preserving mapped history and live leases.
cleanup timeout [DAYS]	Apply timeout collection, optionally with a custom idle retention in days.
cleanup balanced [DAYS]	Apply timeout and soft-budget cleanup with recovery protection, optionally with custom idle days.
cleanup budget MAX_SESSIONS MAX_MIB	Set soft session/byte limits; 0 disables either limit. Active and recently used sessions can remain above a soft budget. Timeout deletion loses ACP-only state but retains OMP history.
diagnostics	Show collection state and non-empty samples as count/median/max per stage.
diagnostics on|off	Enable or disable bounded local timing collection.
diagnostics reset	Clear collected samples without changing the enabled state.
debug on|off	Toggle raw ACP tool-status lines; normal tool results and thought summaries are preserved.
native-tools prefer	Let OMP tools shadow matching ACP-native tools.
native-tools disabled	Disable ACP-native built-ins for strict OMP-tool sessions while retaining MCP configuration; connections are recreated on the next request.
permissions default	Confirm edits and commands.
permissions auto-edit	Auto-accept edits.
permissions yolo	Auto-accept everything; changing modes recreates runtimes to avoid reusing an unsafe process.

Context KEY is one of contextWindow, maxTokens, inputTokenBudget, reserveTokens, maxTransferBytes or maxImageBytes.

The OMP input autocompletes this command. Type /antigravity-acp to list the subcommands, and keep typing to filter them. Fixed values such as permissions modes and context set targets (default plus the cached model IDs) complete the same way.

Steering and queued messages

By default a new user message waits for the active ACP turn to finish (OMP_ACP_STEER_MODE=queue) and then continues on the warm session, avoiding a full replay and OMP auto-compaction. Set OMP_ACP_STEER_MODE=steer to restore immediate interruption. At tool/permission boundaries the adapter falls back to steer and waits for the ACP terminal response; OMP_ACP_STEER_GRACE_MS (default 60000) and OMP_ACP_STEER_GRACE_MAX_MS (default 300000) bound that wait.

ACP runtimes stay warm for 15 minutes by default. Set OMP_ACP_IDLE_TIMEOUT_MS=0 to keep them until OMP exits, or lower the value to reclaim memory sooner.

An ACP turn that ends at the model's output limit is continued on the same session up to three times. OMP_ACP_MAX_CONTINUATIONS=0 disables the loop; if agy already reported its own output-cap continuation, the adapter does not add another.

Inference and /antigravity-acp refresh refuse to start ACP when no local Google login is available; run /login (or /antigravity-acp login) first instead of waiting for an interactive consent flow inside session/new.

Long tools and relay

A tool call that outlives OMP_ACP_TOOL_RELAY_MS (default 85000, 0 disables, otherwise 5000 through 165000) returns a relay notice instead of holding the MCP request open. The model calls pi_omp_await_result with the notice's call_id; the adapter returns the same original result, not a second execution. The control tool is a separate MCP server and is not added to OMP's tool list. If the ACP turn ends before the result arrives, the adapter retries the same result in a fresh ACP turn; it never delivers a stale result to a new writer.

Permission requests are correlated by session, turn and toolCallId with structured mcpServerName/mcpToolName metadata. A conflicting update, a previous-turn id, or a permission-before-update that claims MCP identity is rejected with reject_once when available, otherwise cancelled. Normal requests still go through OMP's human review.

The bridge's MCP tools/list always reflects the current OMP tool set. The offline wire test covers add, remove and restore on one warm ACP session. A live agent re-list has not been verified against the official agy runtime, so the adapter does not claim that the agent will always see a changed list.

A refusal stop reason is reported as an explicit provider refusal. An empty end_turn remains tolerated to preserve OMP's warm /retry path.

Limitations vs direct OAuth

• No direct model API endpoint or reverse-proxy mode.
• No API-key, service-account, or raw OAuth-token authentication; Google browser consent is required.
• Only models advertised by the ACP server are available.
• Only thinking levels confirmed by the ACP server are selectable.
• No arbitrary generation controls: temperature, top_p, seed, stop sequences, tool_choice, response format, or output-token limit.
• No exact API billing or complete subagent usage; cost and quota figures are estimates.
• No guaranteed prompt-cache hits, cache discounts, or identical tokenization.
• No full native history or hidden reasoning across a cold rebuild; server-side compaction is outside adapter control.
• No per-tool native allowlist; native-tools supports only prefer and disabled, and global MCP servers remain.
• No standalone client; the official ACP runtime is required.

Detailed behavior, advanced settings and limitations: docs/ and CHANGELOG.md.

License

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.