# Architecture

Related docs:
- [`../README.md`](../README.md)
- [`../AGENTS.md`](https://github.com/fitchmultz/pi-agent-browser-native/blob/main/AGENTS.md) (maintainer workflows, including upstream capability baseline)
- [`REQUIREMENTS.md`](REQUIREMENTS.md)
- [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md)
- [`ELECTRON.md`](ELECTRON.md)

## Decision

Build this as a **thin `pi` extension/package** that exposes `agent-browser` as one native tool while keeping upstream `agent-browser` as the source of truth.

The package install path is the primary product path. Local checkout development should use explicit CLI loading for isolated smoke tests and configured-source plain `pi` runs for lifecycle validation, while package-manifest behavior and packaged contents matter more.

## Chosen shape

### One primary tool plus optional companion search

V1 exposes one native browser tool:

- `agent_browser`

It may also expose one optional companion tool:

- `agent_browser_web_search`, available when an Exa or Brave Search credential source is configured or resolvable from startup config or trusted session config and runtime `webSearch.enabled` is not false

Why:
- keeps browser automation centered on `agent_browser`
- avoids colliding with generic `web_search`
- keeps live search separate from browser state, screenshots, refs, and session lifecycle
- supports requested Exa/Brave provider choice without turning search into an `agent_browser` input mode
- keeps optional search invisible when it cannot run or when the user disables it

### Direct subprocess execution

The extension should:
- resolve `agent-browser` from `PATH`
- invoke it directly on POSIX; on Windows, route through PowerShell with single-quoted argv so npm launchers and the native `.exe` receive the same command tail that a user would type, and terminate the full PowerShell/agent-browser process tree with `taskkill /T /F` on timeout or abort before falling back to the direct child signal
- inject `--json`
- complete each upstream invocation when the direct `agent-browser` child exits even if Node delays `"close"`: piped stdio can stay referenced by longer-lived descendant processes, so `runAgentBrowserProcess` watches `exit` and `close` together, leaves stdio intact during a short post-`exit` grace so normal `close` can still win, destroys streams only when the post-`exit` fallback fires, and prefers `close` codes then wrapper timeout (`124`) over signal-shaped `exit` codes (`watchSpawnedChildCompletion` / `resolveSpawnedChildExitCode` in `extensions/agent-browser/lib/process.ts`) so the tool cannot hang after the CLI process has already terminated
- support optional stdin only for `eval --stdin`, `batch`, `auth save --password-stdin`, and wrapper-generated `batch` stdin from top-level `job`, `qa`, `sourceLookup`, or `networkSourceLookup`, rejecting other command/stdin combinations before launch; top-level `electron` never accepts caller `stdin` (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#electron))
- support optional top-level `outputPath` for successful browser results by writing `details.data` (or model-facing text when no structured data exists) to a caller-requested local file and reporting `details.outputFile`, without changing upstream argv semantics or overwriting a browser artifact when both destinations resolve to the same file
- support optional top-level `timeoutMs` as a per-call subprocess watchdog override for browser CLI input modes while keeping Electron-specific timeouts inside the `electron` object
- accept an optional native `semanticAction` object as a mutually exclusive alternative to `args` on a single tool call (and to `job`, `qa`, `sourceLookup`, `networkSourceLookup`, and `electron` on the same call), compile locator actions into upstream `find` argv, direct selector/ref click/check/fill into upstream command argv, and native dropdown selection into upstream `select <selector> <value...>` argv (with optional `semanticAction.session` expanding to a leading `--session <name>` before the compiled command when targeting a named upstream browser instead of the managed default), and echo the compiled shape in `details.compiledSemanticAction` for observability (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#semanticaction))
- accept an optional native `job` object (mutually exclusive with `args`, `semanticAction`, `qa`, `sourceLookup`, `networkSourceLookup`, and `electron` on the same call) with a small fixed step vocabulary that compiles only to existing upstream `batch` argv rows, generates the JSON batch stdin string internally, defaults to fail-fast `batch --bail` unless `failFast:false` is explicit, supports semantic locator fields on constrained `click`/`fill` steps by reusing the top-level semantic-action compiler, supports human-paced `type` by expanding to a bounded set of existing focus/keyboard/wait/press rows while compacting model-visible batch text, and echoes `details.compiledJob` for observability (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#job))
- accept an optional native `qa` object (mutually exclusive with `args`, `semanticAction`, `job`, `sourceLookup`, `networkSourceLookup`, and `electron` on the same call) that compiles to the same fail-fast `batch --bail` path as `job`, runs a fixed diagnostic smoke sequence with bounded visible-text predicates for `expectedText`, preserves existing diagnostics for `qa.attached` while clearing buffers only for URL-opening QA, and echoes `details.compiledQaPreset` plus structured `details.qaPreset` pass/fail evidence (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#qa))
- accept an optional native `sourceLookup` object (mutually exclusive with `args`, `semanticAction`, `job`, `qa`, `networkSourceLookup`, and `electron` on the same call) that compiles to the same `batch` path, gathers evidence-backed local source *candidates* for a selector/fiber/component name, and echoes `details.compiledSourceLookup` plus structured `details.sourceLookup` (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#sourcelookup)); unlike `qa`, it never applies a second pass/fail layer that marks the tool failed when upstream already reported batch success—failed upstream steps still fail the invocation normally, and `details.sourceLookup` may still be present for partial evidence
- accept an optional native `networkSourceLookup` object (mutually exclusive with `args`, `semanticAction`, `job`, `qa`, `sourceLookup`, and `electron` on the same call) that compiles to the same `batch` path, correlates failed network requests with initiator metadata and bounded workspace URL literals, and echoes `details.compiledNetworkSourceLookup` plus structured `details.networkSourceLookup` (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#networksourcelookup)); like `sourceLookup`, it never flips a successful upstream batch to failed solely because no source candidates were found
- accept an optional native `electron` object (mutually exclusive with `args`, `semanticAction`, `job`, `qa`, `sourceLookup`, and `networkSourceLookup` on the same call) for bounded desktop Electron lifecycle: `list` scans the host for install candidates, `launch` creates a wrapper-owned isolated profile plus OS-chosen remote-debugging port, then attaches through upstream `connect` with `sessionMode: "fresh"`, cancellation prevents host spawn or interrupts readiness polling with process/profile cleanup, and `status` / `cleanup` / `probe` operate only on wrapper-tracked launches; host-side spawn and CDP discovery live in `extensions/agent-browser/lib/electron/discovery.ts`, `launch.ts`, and `cleanup.ts`, while compilation, transcript restore for `launchId` records, handoff probes, and merged `details.electron*` fields live under `extensions/agent-browser/lib/orchestration/electron-host/` and `extensions/agent-browser/lib/orchestration/browser-run/` (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#electron))
- when a compiled `find` semantic action fails as `stale-ref`, optionally append a `retry-semantic-action-after-stale-ref` entry to `details.nextActions` after the usual `refresh-interactive-refs` snapshot step so agents can re-issue the same compiled `find` argv only when the failure implies the interaction did not run; `select` shorthands with stale `@refs` get refresh guidance only (contract in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#semanticaction))
- when the same compiled path fails as `selector-not-found` for the bounded locator/action pairs documented there, optionally append `try-*-candidate` entries to `details.nextActions` and mirror them in visible text as `Agent-browser candidate fallbacks` so agents can retry role/name `find` variants without hand-rebuilding argv (`select` misses are intentionally excluded)

### Agent-first UX

The primary UX is the agent calling the tool directly.

That means:
- no command-heavy slash-command interface
- no manual user orchestration as the main workflow
- any future slash commands should be minimal and secondary

### Package-owned config

Pi docs use `settings.json` for package/resource loading and filtering, not arbitrary extension secrets. For user-tunable package behavior, this package owns Pi-scoped config files instead:

- global: `~/.pi/config/pi-agent-browser-native/config.json`
- project-local: `.pi/config/pi-agent-browser-native/config.json`
- explicit override: `PI_AGENT_BROWSER_CONFIG=/path/to/config.json`

Config layers merge in that order: global, project, override. The shared policy module (`extensions/agent-browser/lib/config-policy.js`) owns provider descriptors, environment variable names, config keys, credential source parsing, developer-trusted project layer inclusion, layer validation/merge, redacted status projection, and credential summaries for both runtime config loading and the package config helper. Under Pi 0.84.0+, globally installed or CLI-loaded extensions are developer-trusted code, so this extension reads `.pi/config/pi-agent-browser-native/config.json` by default and skips that project layer when Pi reports the project is untrusted or when launched with `--no-approve`. Global config and explicit `PI_AGENT_BROWSER_CONFIG` overrides remain available either way. The config reader accepts v1 fields for `webSearch.enabled`, `webSearch.preferredProvider`, `webSearch.exaApiKey`, `webSearch.braveApiKey`, and conservative browser defaults such as `browser.defaultProfile` and `browser.executablePath`. Web-search key fields follow Pi model/provider-style value resolution from any loaded layer: literal values, `$ENV_VAR` / `${ENV_VAR}` interpolation, escapes (`$$`, `$!`), and leading `!command` resolved at request time. `EXA_API_KEY` and `BRAVE_API_KEY` remain environment fallbacks when no config credential source exists for that provider. Browser default values keep their source scope; prompt guidance is emitted from the highest-priority loaded layer, including project config when Pi trust/loading allows it.

`agent_browser_web_search` availability is conditional. Startup registration uses global, override, and environment fallback config without reading project-local config before Pi trust context exists; trusted project config can register the companion tool on `session_start`, and every execution reloads the final session config so `webSearch.enabled: false` still prevents a request even if a startup credential made the tool visible. A global disable is the normal user default and can still be overridden by project config or `PI_AGENT_BROWSER_CONFIG`; a project disable applies to one repo; an explicit `PI_AGENT_BROWSER_CONFIG` file with `webSearch.enabled: false` is the highest-priority hard disable for that run. Literal and env-backed sources must resolve before they make the tool available; command-backed sources are considered configured without running the command until tool execution, so secret managers do not slow startup or prompt unexpectedly. The tool resolves the selected key lazily, chooses Exa or Brave from available credentials (preferring Exa by default unless `webSearch.preferredProvider` says otherwise), then follows one provider-agnostic execution path through provider adapters for request building, HTTP JSON fetch, response normalization, and provider-specific detail fields. It calls Exa `/search` with highlights or Brave Search and returns compact result details without exposing keys.

Browser default config is intentionally advisory. It can add prompt guidance for signed-in/account-specific tasks and alternate Chromium-compatible executables, but current releases do not auto-inject `--profile` or `--executable-path` into every launch. Loaded project config can provide the same guidance as global and override config; Pi/project trust decides whether that project layer is loaded. Automatic launch-default mutation would affect privacy, browser state, and host executable choice, so it needs a separate explicit design and test pass.

### Prompt guidance budget

Runtime `promptGuidelines` are a Tier A budget, not a full manual. They stay short enough to load on every `agent_browser`-aware turn and carry only high-impact rules: input-mode choice, the open → snapshot → ref loop, launch-scoped session handling, artifact verification, structured `nextActions`, extraction basics, and hard agent-responsibility boundaries such as “stop before order/post/purchase/submit.”

Tier B guidance lives in `SHARED_BROWSER_PLAYBOOK_GUIDELINES`, generated README/command-reference fragments, and targeted docs. When a workflow needs examples, caveats, or long command-family coverage, add it there instead of expanding always-on prompt text. If a Tier B rule prevents a repeated real failure, promote only the smallest durable sentence into Tier A and keep the generated-doc mirrors aligned.

### No reusable recipe layer yet

Do **not** add reusable browser recipes as a first-class runtime surface yet.

Current evidence does not justify another source of truth for workflows:
- unit/fake-upstream coverage and real-app dogfood exercise `job`, `qa`, experimental lookups, and `electron` lifecycle without a separate accounting benchmark layer
- repo-local dogfood evidence does not show repeated project-specific job recipes that need versioning or ownership
- `qa` already covers the only repeated smoke-test shape with a stable top-level preset
- docs and prompt guidance can carry examples without adding recipe state, migration rules, or another schema

Revisit this only when dogfood data shows at least two repeated, failure-prone job sequences that cannot be represented clearly by `job`, `qa`, top-level `electron`, or raw `batch`. If that happens, define ownership, versioning, schema boundaries, generated docs, and tests before adding executable recipes.

### Package layout versus local checkout development

The published package should load from the `pi` manifest in `package.json`.

Local checkout validation has two intentional modes:

- **Quick isolated mode:** use explicit CLI loading such as `pi --approve --no-extensions -e .` from the repository root when this checkout is intentionally trusted. This bypasses Pi settings and extension discovery, avoids duplicate `agent_browser` registrations when another source is installed globally, and is the right mode for checkout smoke tests; omit `--approve` only when deliberately testing Pi's Project Trust prompt.
- **Configured-source lifecycle mode:** configure exactly one active checkout or package source in Pi settings and launch plain `pi` for manual validation, or run the automated harness that launches with `--approve`. This is the right mode for validating `/reload` and exact-session relaunch because those lifecycle checks exercise discovered/configured resources. Focused extension harness tests validate branch-backed `session_tree` rehydration and cleanup ownership. Before shipping, maintainers also run `npm run verify -- lifecycle` (same semantics under automation, using Pi 0.84.0+ `--approve --session-id` to reopen the exact JSONL session) plus the live-site checks in [`RELEASE.md`](RELEASE.md#pre-release-checks); `npm publish` enforces `npm run verify -- release` via `prepublishOnly` unless scripts are skipped.

The repo should not add a repo-local `.pi/extensions/` autoload shim as the documented checkout path.

Why:
- avoids duplicate `agent_browser` registrations when the package is also installed globally
- keeps the product contract centered on the package manifest instead of repo-local autoload wiring
- keeps reload and exact-session relaunch validation tied to Pi's configured-source lifecycle instead of an isolated quick-test path, while `session_tree` state changes stay covered by focused extension harness tests
- keeps the published tarball focused on the package manifest, extension code, canonical docs, and license

The published package should exclude agent-only and internal planning materials such as `AGENTS.md`.

## Session model

### Default

If the caller does not provide `--session`, the extension should default to `sessionMode: "auto"` and use an implicit session name derived from the current `pi` session id plus a hash of the absolute cwd.

Why:
- works out of the box
- gives continuity across calls
- avoids forcing the agent to invent session names for basic browsing

### Explicit upstream sessions and fresh launches

If the caller provides `--session`, `--profile`, `--cdp`, or similar upstream flags, the extension should respect them with minimal interference.

The tool should also expose a first-class `sessionMode: "fresh"` escape hatch so agents can intentionally rotate the extension-managed session to a fresh upstream launch without inventing a fixed explicit session name.

### Ownership

V1 ownership rule:
- implicit auto-generated sessions are extension-managed convenience sessions
- unnamed `sessionMode: "fresh"` launches rotate that extension-managed session to a new upstream browser
- explicit/user-managed sessions are not auto-managed by default
- extension-managed sessions should be reusable during an active `pi` session and across `/reload`, exact-session relaunch, `/resume`, and Pi branch-tree transitions, while still being cleaned up predictably

Practical policy:
- preserve the current branch-visible extension-managed session across `/reload`, exact-session relaunch, `/resume`, and Pi 0.84.0+ `session_tree` branch transitions so persisted sessions can keep following the live browser after lifecycle changes
- close the active extension-managed session when the originating `pi` process quits, while leaving explicit caller-provided sessions alone
- set an idle timeout on extension-managed sessions as a backstop for abnormal exits or cleanup failures, and apply that same `AGENT_BROWSER_IDLE_TIMEOUT_MS` value to every upstream subprocess (including wrapper helper snapshots, tab lists, and navigation-summary reads) because changing the launch environment between calls can make upstream restart the background browser, discard the active tab, and invalidate fresh refs
- for wrapper-owned managed sessions only, also set a Git-checkout-generation-stable `AGENT_BROWSER_RESTORE` key on every compatible non-close upstream subprocess so cookies, localStorage, and sessionStorage autosave/restore across idle shutdowns and later Pi chats in the same checkout generation. The wrapper stores a UUID in the resolved Git admin directory and combines it with the checkout root and Git-admin directory filesystem identities: renames preserve the key, copied or path-replacement checkouts get a new key, non-Git directories fail closed, and cwd-only keys are not adopted. Policy lives in `extensions/agent-browser/lib/managed-session-restore.ts`; ownership is resolved by `resolveOwnedManagedSessionContext` (injected managed session, or explicit `--session` equal to the current managed name and namespace) and applied through `AsyncLocalStorage` `withOwnedManagedSessionContext` for prepare helpers plus main process/output, with typed `ownedManagedSession` process options for owned main/close spawns rather than an internal marker leaked into the child environment. `buildOwnedManagedSessionRestoreContext` sets call-scoped `restoreSuppressed` from main-plan argv so helper probes skip restore on incompatible plans without sticky-disabling when prepare returns early; sticky disable commits only after an owned-context subprocess actually starts with suppressed restore policy: POSIX commits on child `spawn`, while PowerShell-backed Windows commits after completion unless command-not-found stderr proves `agent-browser.cmd` never started. No-spawn preflight and missing-binary failures never commit an identity. Duplicate `--session` or `--namespace` flags are rejected, as are leading equals forms that upstream 0.33.2 does not recognize; global identity/config scanning follows upstream across the full argv rather than treating `--` as a sentinel. Native Windows command-first launcher adaptation relocates only valid leading global syntax, canonicalizes a valued optional `--restore <name>` to `--restore=<name>`, consumes only exact lowercase boolean literals, and leaves command-scoped, unknown, or unsupported equals-form input untouched so invalid calls cannot become valid browser activity. Namespace values are canonicalized with upstream's lowercase `sanitize_session_component` algorithm before ownership, sticky/page state, details, socket, or restore-directory identity comparisons; every wrapper-owned subprocess also pins that canonical namespace, including an empty default namespace, so parent environment cannot redirect helpers or close. Electron status target reads and current-managed probes acquire the same daemon-policy lock and owned restore context as ordinary commands for their underlying reads. Probe results then persist the same namespace plus top-level tab/ref state, keeping branch replay keyed to the probed identity. Ownership is typed rather than inferred from a name prefix, and `piab-*` live-session names are reserved: an explicit target is accepted only when it is the current/generated managed session or appears in this extension instance's ownership records. `session list` hides those rows, and the same reservation is rechecked at the final process boundary so another Pi process cannot attach to a managed authenticated browser through the shared per-user daemon socket. Skip when the caller already set restore/profile/state/CDP/provider/auto-connect/containment/session-name or a browser mutation surface (custom executable, extension, init script, raw launch args, proxy, plugin, WebGPU, or related engine/device controls) via argv or matching parent env, when the command is `connect`, when raw batch argv is used, when batch stdin contains nested `connect`/`batch`, or when `PI_AGENT_BROWSER_MANAGED_SESSION_RESTORE=0`. The wrapper's own site-specific headless user-agent compatibility injection is excluded from caller-mutation policy and remains pinned across follow-up subprocesses for the active managed session. For those owned sessions only, the process boundary also replaces the otherwise-empty safe `--args` value with a fixed, comma-safe Chrome `--user-agent=...` launch argument so new targets inherit the compatibility value; upstream's normal `--user-agent` flag applies only to the active CDP target. A user-private immutable ticket-claim lock keyed by canonical namespace/session serializes this inspect-through-spawn decision across cooperating Pi processes; every contender publishes a unique claim, deterministic tickets elect one owner, and the winner also holds the legacy v2 path as a bridge. The bridge is transitional for pre-release branch processes and is scheduled for removal after v0.2.74 in [#93](https://github.com/fitchmultz/pi-agent-browser-native/issues/93). Live pre-update processes and their in-flight candidate gaps therefore block new acquisition; an abandoned v2 owner fails closed for manual repair, while current-protocol recovery removes only unique claims and artifacts with proven-dead PID/start identity. Waits are asynchronous and bounded. Ordinary acquisition waits one second and fails with retry guidance rather than queueing behind another process's in-flight command, which may retain the lock through a 35-second daemon inspection and the requested browser operation. Every policy-lock winner re-runs `session info` even when this process previously recorded the applied/observed restore key, because another process can restart the same daemon identity between calls. That inspection uses a fixed bounded timeout independent of a caller's shorter `PI_AGENT_BROWSER_PROCESS_TIMEOUT_MS` override. Before an incompatible call, the wrapper reads `session info` for the actual same-identity daemon and fails before the requested spawn when that daemon retains any restore key or cannot be inspected. This covers restore-enabled daemons missing from transcript state after a crash and managed sessions launched with an explicit caller restore key; a confirmed inactive daemon remains reusable; a restore-disabled daemon is reusable only when this process recorded its expected null/custom restore policy after an owned spawn or successful policy match. After reload clears process-only provenance, an inactive old daemon may be restarted without restore and that started subprocess records a null daemon policy for its next follow-up. Same-process `session_tree` branch changes retain that process-owned provenance; a new extension instance after reload, restart, or `/resume` intentionally starts without it and fails closed on a still-live restore-disabled daemon even when the transcript restores sticky-disable state. Close the retained-key daemon first, use a fresh wrapper session, or choose a distinct explicit session. Once a managed session hits any allowed incompatible launch path, restore stays disabled for later bare follow-ups on that same session identity. Sticky identities live in the extension-owned `ManagedSessionRestoreState` instance, persist as `details.managedSessionRestoreDisabled`, and are replaced from current-branch rows during branch restore rather than stored in module-global process state. The opt-out returns before config/storage probes and sticky-records a successfully spawned identity as restore-disabled, allowing later calls to reuse that non-restore daemon without tripping the active restore-enabled conflict gate. This is env-based persistence, not a hidden argv relaunch. Upstream still owns restore file paths/modes under `~/.agent-browser/`; set `AGENT_BROWSER_ENCRYPTION_KEY` on multi-user hosts if plaintext session files are unacceptable. Any project `./agent-browser.json`, explicit `--config` / `AGENT_BROWSER_CONFIG`, or `~/.agent-browser/config.json` discovered while planning disables managed restore without reading caller-selected content in the Pi host; owned spawns sticky-disable that session identity. Each subprocess that receives the wrapper restore key, plus every wrapper-owned close, overrides config discovery with a process-private empty `AGENT_BROWSER_CONFIG` (`0400` on POSIX) inside the canonical marked `0700` secure-temp root, closing the check-to-spawn race without trusting project or user config while retaining normal shutdown cleanup and PID/start-identity stale-root recovery after abnormal exit on POSIX and native Windows; versioned Windows identities treat legacy cross-format markers as unknown instead of incorrectly proving PID reuse, and temp ownership marker schema v2 makes older readers ignore new-format markers. Spawn-time revalidation rejects changed checkout identity, restore storage, unpinned launch-mutator environment, foreign managed-session targets, or forbidden managed-state access before agent-browser starts; the same check runs again after protected-config and socket-directory awaits immediately adjacent to the synchronous spawn. A failed fresh command that started agent-browser triggers an exact-identity daemon probe; an active or uninspectable daemon remains current and wrapper-owned so shutdown cleanup can close it, while pre-aborted and missing-binary calls remain unowned. Wrapper-owned close commands canonicalize upstream argv to JSON plus the known namespace/session and `close`, discarding caller config/restore globals, and do not inject a newly derived restore key into an existing daemon, so checkout replacement cannot make old auth save under the replacement generation; the close path retains the observed wrapper key long enough to record the returned old-generation snapshot safely. Because upstream writes a snapshot per daemon session, a successful wrapper-owned close requests JSON output and persists only the returned state path as an atomic record in a lockless convergent per-key ownership directory beside the snapshots (`0700`, with `0600` records, on POSIX). Cleanup carries that ownership proof across Pi restarts, self-heals malformed or stale regular records without claiming their snapshots, uses immutable atomic record names plus rescan-after-delete convergence so concurrent closers cannot skip ownership recording or exceed the aggregate cap, removes proven snapshots older than 30 days for the exact restore key while retaining the two newest, expires stale ownership-proven snapshots and empty manifests from other restore-key generations after 30 days only when a private lineage record proves the same canonical checkout path, caps young close churn at 256 records per key, and never deletes matching unrecorded files or the current checkout key. Upstream restore files under `~/.agent-browser/` remain plaintext unless `AGENT_BROWSER_ENCRYPTION_KEY` is set; before automatic managed restore the wrapper requires a durable Git generation and absolute platform home root; it pins the planned encryption-key value after caller env merging; on POSIX it also resolves `HOME` once, validates owner-trusted non-writable ancestry plus stable device/inode/birth-time metadata for both checkout and Git-admin directories, and pins that canonical value, enforces mode `0700` without silently repairing unsafe existing paths, and rejects symlinks/non-directories along the exact `~/.agent-browser[/namespaces/<canonical>/state]/sessions` path and its `.tmp` transactional-write area, while Windows requires an absolute `USERPROFILE` and the documented 64-character hex encryption key because POSIX mode checks cannot verify profile ACLs; malformed keys fail closed on every platform. POSIX process-start probes use absolute `/bin/ps` then `/usr/bin/ps`; if neither is available, managed policy locking fails closed with an actionable validation message. Managed `piab-r2-*` keys and key-bearing paths are redacted from visible/structured/JSON transcript surfaces. Malformed oversized upstream output is discarded after parsing rather than copied into a persistent parse-failure spill, and raw parse-failure stdout is omitted from result details. `session list` and `state list` filter wrapper-managed rows, and the pre-spawn policy blocks foreign managed restore/state references, broad clear/clean operations, and managed save/rename targets while preserving targeted caller-owned state workflows.
- clean up process-private temp spill artifacts on shutdown, but keep persisted-session snapshot spill files in a private session-scoped artifact directory with a bounded per-session budget so `details.fullOutputPath` stays usable after reload/resume without unbounded growth
- keep explicit screenshots, downloads, PDFs, traces, HAR captures, and recordings written to caller-chosen paths on disk after a successful upstream close command (`close`, `quit`, or `exit`); before artifact-producing commands run, create missing parent directories for requested host paths, and for simple loopback HTML anchor downloads with resolvable HTTP(S) hrefs the wrapper may save directly to the requested path before upstream fallback. When the bounded `details.artifactManifest` has entries, successful close commands also surface `details.artifactCleanup` and a compact `Artifact lifecycle` note pointing to structured explicit paths so operators remove files with normal host tools—the native tool does not delete arbitrary user paths (`extensions/agent-browser/lib/orchestration/browser-run/diagnostics.ts`, `getArtifactCleanupGuidance`); contract in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details), checklist `RQ-0079` in [`SUPPORT_MATRIX.md`](SUPPORT_MATRIX.md)
- reconstruct the current branch-visible extension-managed session, every transcript-proven still-active wrapper-owned managed identity, page-scoped refs, newest-revision aggregate artifact manifest, and Electron launch records from the active transcript branch on `session_start` and `session_tree` so later default and explicit off-current calls keep following owned browsers after resume/reload or branch switching; restore also honors successful explicit `--session <wrapper-owned> close` rows and `electron.cleanup` managed-session steps so closed wrapper-owned sessions are not resurrected
- keep process-owned cleanup registries for extension-managed sessions and wrapper-launched Electron records separate from the current branch-visible view; `session_tree` restore and wrapper-owned browser commands are serialized with managed-session work, while caller-owned explicit-session commands are serialized by process-local queues keyed to effective canonical namespace/session across prepare helpers (explicit namespace argv overrides inherited `AGENT_BROWSER_NAMESPACE`, including an explicit empty default) and main execution. macOS and Windows additionally normalize and case-fold namespace and session components to match case-insensitive daemon identity. Different caller-owned identities remain concurrent, nested helpers never re-enter the outer queue, policy/route/artifact deltas merge across unrelated managed-state commits, and a separate branch-restore generation guard prevents stale completions from overwriting newer branch-visible state; aggregate artifact results use monotonic revisions so transcript replay cannot lose a concurrently completed entry. Branch switches still must not drop resources the current Pi process owns and must keep fresh-session allocation monotonic
- record successful `connect`, `--cdp`, enabled `--auto-connect`, environment-configured CDP/auto-connect, and wrapper Electron attachment identities in branch-visible state, then run their main commands, helper probes, and cleanup inside an attached-browser process context that omits wrapper launch-only `--args` / `--allow-file-access` defaults. Re-sending those flags makes upstream choose local launch instead of its existing CDP connection and can trigger remote-debugging permission on every call. Block first-use attachment/content combinations until URL verification, and apply the existing live `get url` gate before every later content-bearing read or interaction because attached targets can drift outside Pi. Every child clears `AGENT_BROWSER_ALLOW_FILE_ACCESS`, including attached calls that omit the canonical launch flags. Successful close removes the marker; existing config, environment, URL, and protected-path checks still apply
- when a successful close targets the current extension-managed session, including an explicit `--session <current> close` or an `electron.cleanup` managed-session step, clear page/ref state, mark that session inactive, untrack cleanup ownership, and rotate the next default auto call to a fresh wrapper-generated session name rather than reusing the closed name
- on non-quit shutdown such as `/reload`, close off-branch owned managed sessions and off-branch owned Electron launches before clearing process-local ownership, but preserve the current branch-visible active managed session and Electron launch plus that launch's isolated `userDataDir` so reload continuity still works from the active transcript branch
- expose still-owned off-branch Electron launch records to `electron.status { launchId }`, `electron.status { all: true }`, `electron.probe { launchId }`, and `electron.cleanup`, while leaving default `electron.probe` scoped to the current managed session
- if an unnamed fresh launch replaces an active extension-managed session, best-effort close the old managed session after the switch succeeds; `managedSessionOutcome.replacedSessionClosed` records whether that cleanup succeeded, and a failed close keeps the older identity wrapper-owned across transcript resume for explicit follow-up or cleanup
- leave explicit caller-provided `--session` choices alone unless the caller closes them explicitly, but before any content-bearing read or interaction against a caller-owned explicit session, live-probe that session with `get url` and apply the local-state boundary to the observed target instead of trusting missing or stale transcript page state; hold the effective canonical namespace/session queue from that probe through semantic snapshot resolution and the main command so another same-instance call cannot change tabs in between. Non-bail batch analysis retains every possible page left by a failed transition up to a fixed bound and blocks later content when any such page is local or unverified; exceeding the bound also fails closed to exact `batch --bail` guidance, while exact `batch --bail` or split calls make that dependency fail-safe. Protected Windows paths include drive-relative `C:...` forms, nested `batch` steps fail closed, and raw batch command strings mirror upstream's ASCII-space tokenizer, including quote/backslash handling, rather than splitting on other Unicode whitespace
- after profiled `open` / `goto` / `navigate` calls, verify the active tab still matches the returned page URL and best-effort switch back when restored profile tabs steal focus
- once the wrapper observes tab-drift risk for a session (profile restore correction, overlapping stale opens, or restored session state), later active-tab commands may synthesize a tiny upstream `batch` that re-selects that tab and then runs the requested command in the same upstream invocation; routine same-session commands avoid `tab list` preflights to reduce probes that can perturb upstream click behavior
- for sessions with observed tab-drift risk, after a successful command on a known tab target, the wrapper may best-effort restore that same target again if restored/background tabs steal focus after the command returns; routine same-session commands skip this post-command `tab list` probe
- after successful `tab close`, read the now-active URL/title before updating per-session page state because upstream's close payload identifies the closed tab but does not report the remaining active tab; this keeps subsequent ref guards and interactions aligned without requiring a recovery snapshot solely to repair wrapper state
- keep a per-session `refSnapshot` aligned with the last successful `snapshot` (including refs merged from a successful `batch` by taking the last successful `snapshot` step in batch result order): restore it from persisted tool `details` when reloading, resuming, or moving to a different Pi session-tree branch, store bounded ref role/name metadata from the same snapshot for wrapper-side current-ref diagnostics, drop it on successful close commands (`close`, `quit`, or `exit`), and refuse mutation-prone `@e…` argv before spawn when the active tab URL no longer matches the snapshot URL, when a ref id was never in that snapshot, or when `batch` stdin would reuse `@e…` on a guarded step after an earlier invalidating step without a later `snapshot` step in the same stdin array. Same-snapshot `fill @e…` rows are guarded but do not themselves set that invalidation latch, so ordinary form fills can precede a click/submit row in one batch—see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details) for the agent-visible contract and failure text; typed per-session tab/ref/pinning state lives in `extensions/agent-browser/lib/session-page-state.ts` and is updated from `extensions/agent-browser/index.ts` after each tool result
- for top-level non-Electron direct `click` commands with an eligible target, install a bounded in-page target-specific event probe before upstream runs; if upstream reports success but no trusted pointer/mouse/click event reached the resolved target, fail the tool and report `details.clickDispatch` with explicit retry/inspect next actions (the wrapper does not replay clicks in-page). The probe covers `xpath=` targets and current `@e…` / `ref=` refs whose latest stored `refSnapshot.refs` role is `button`, `checkbox`, `menuitem`, `radio`, `switch`, or `tab`; it uses that role/name metadata, including snapshot-order `duplicateIndex` for duplicate-name refs, instead of taking a fresh pre-click snapshot that could recycle upstream refs. The probe is intentionally skipped for CSS selector clicks, unresolved `find … click` locators, and `batch`/`job`/`qa` click steps
- derive narrow prompt guards only for concrete evidence invariants: explicitly requested screenshot/recording output paths block browser close until the artifact manifest verifies those paths, while bare inbound attachment paths remain inputs. The wrapper intentionally does not infer broad business/user intent from prompt text such as order/payment/post boundaries; agents must follow those instructions themselves. The artifact guard is bounded preflight policy (`details.promptGuard`, `failureCategory: "policy-blocked"`), not a reusable browser recipe layer
- after successful `get text` on a qualifying non-ref CSS selector, optionally issue one read-only `eval --stdin` probe per selector when multiple DOM matches or a hidden first match with visible peers could misread tabbed or off-screen content; simple id selectors and sensitive-looking literals skip this probe. Merge `details.selectorTextVisibility` / `selectorTextVisibilityAll`, visible warning lines, and `inspect-visible-text-candidates*` next actions as documented in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details) and `RQ-0074` in [`SUPPORT_MATRIX.md`](SUPPORT_MATRIX.md)
- for local Unix launches, set a short private socket directory so extension-generated session names do not fail on the upstream Unix socket-path length limit; require the selected path to be absolute, owned by the current uid, mode `0700`, under trusted non-replaceable ancestry, and free of symlink, foreign-owner, or special planted entries; reject pre-existing unsafe modes instead of repairing them, then recheck before spawn
- keep wrapper-spawned upstream CLI calls bounded by clamping `AGENT_BROWSER_DEFAULT_TIMEOUT` to the upstream documented 25-second default while deriving a longer subprocess watchdog for explicit long `wait <ms>` / `wait --timeout <ms>` calls; dialog commands, likely dialog-trigger clicks/taps/finds, and `eval --stdin` snippets that look like alert/confirm/prompt/dialog triggers use shorter wrapper subprocess budgets so blocking JavaScript prompts surface recovery actions before the full default watchdog

This is primarily about ownership clarity and avoiding surprise, not adding a heavy safety wrapper. If the extension invented the session, the extension should own its lifecycle without breaking reload, resume, or branch-tree semantics. If the caller explicitly chose the upstream session model, the extension should stay out of the way.

### Launch flags

`agent-browser` startup flags are sticky once a session is already running.
The extension should surface that clearly and avoid hidden restart behavior in v1.

That means explicit startup-scoping flags like `--allowed-domains`, `--auto-connect`, `--cdp`, `--enable`, `--executable-path`, `--webgpu`, `--headed`, `--init-script`, `--device`, `--namespace`, `--profile`, `--provider`, `-p`, `--restore`, `--restore-save`, restore check flags, `--session-name`, and `--state` should remain explicit upstream argv choices instead of being wrapped in extra hidden restart or cloning logic. The one deliberate exception is the env-only managed-session `AGENT_BROWSER_RESTORE` key above, which does not inject `--restore` into argv and therefore does not trip launch-scoped `sessionMode: "fresh"` recovery.

The wrapper may still apply narrow compatibility normalizations when observed behavior justifies them and the result remains thin, local, and opt-out. For example, OpenAI web properties and `dash.cloudflare.com` reject the default local `HeadlessChrome` user agent while the same flow works with a normal Chrome UA, so the extension injects a domain-specific fallback only when the caller did not already choose raw Chrome arguments, a custom user agent, headed mode, CDP, auto-connect, a provider-backed launch, or a non-Chrome engine through argv or matching upstream environment. Managed sessions retain the injected value across helper and follow-up subprocesses, including branch reload/resume, because omitting it can make upstream relaunch the browser with a different launch identity. The process boundary also pins the same fixed compatibility value as a comma-safe Chrome launch argument for owned sessions, covering tabs and SSO popups that do not inherit upstream's per-page CDP override. Wrapper-owned headed launches also default upstream periodic restore autosave off because agent-browser 0.33.2 collects non-current origins through visible temporary targets while holding the daemon state lock; save-on-close remains enabled, and an explicit `AGENT_BROWSER_AUTOSAVE_INTERVAL_MS` value opts in when the daemon launches. The effective interval is retained in owned-session state and transcript results; changing it in either direction on a running wrapper-owned headed daemon is rejected until close plus a fresh launch.

If the implicit session is already active and one of those startup-scoped flags appears again while `sessionMode` is still `"auto"`, the extension should fail clearly instead of silently sending a command shape that upstream would ignore.

That failure should include a structured recovery hint pointing to `sessionMode: "fresh"` as the first-line fix, while still allowing an explicit `--session` when the caller wants to name the new upstream session.

Implementation detail lives in `extensions/agent-browser/lib/launch-scoped-flags.ts` (canonical flag metadata shared with playbook/docs assertions), `extensions/agent-browser/lib/argv-descriptor.ts` and `extensions/agent-browser/lib/argv-grammar.ts` (command discovery, `VALUE_FLAGS`, `parseArgvDescriptor`) plus `extensions/agent-browser/lib/runtime.ts` (`getStartupScopedFlags`, `buildExecutionPlan`):

- **Command discovery:** Leading argv is scanned with a value-taking allowlist so known global flags and documented command flags consume their values before the upstream command word is identified. Missing-value prevalidation is intentionally limited to upstream global value flags; command-scoped flags and literal text are left to upstream parsing so values like `fill #field --password` are not rejected by wrapper heuristics before the CLI sees them. When upstream adds new global flags that take values ahead of the command, extend both the command-discovery and prevalidation allowlists; when it adds command-specific flags, extend only command discovery/redaction as needed. A smaller set of global boolean flags may be followed by an optional `true`/`false` literal; when present, that literal is consumed as the flag value before command discovery continues.
- **`--state` disambiguation:** Persisted browser `--state` before the command participates in launch-scoped validation and tab-correction hints. The same flag spelling after a `wait` command is excluded from startup-scoped detection so upstream help examples such as `wait @ref --state hidden` do not spuriously require `sessionMode: "fresh"` while an implicit session is active. As of the current upstream baseline, the parser still does not implement those `wait --state` examples as distinct wait modes, so agent-facing docs recommend `wait --fn` predicates for disappearance checks instead.
- **`--auto-connect`:** Treated as launch-scoped only when enabled (`--auto-connect` bare or `true`). `--auto-connect false` is ignored for startup-scoped blocking so disabled attach hints do not force a fresh launch.
- **`--webgpu`:** Treated as launch-scoped for both enabled and explicit `false` values. Enabled WebGPU selects upstream's platform-specific local-launch preset; explicit false can override an environment/config default and still belongs to a fresh browser launch. Upstream rejects enabled WebGPU with CDP, auto-connect, or provider launches.
- **`--headed`:** Treated as launch-scoped for both enabled and explicit `false` values so a visible-window choice cannot be silently ignored by an already-running managed session.
- **`--allowed-domains`:** Treated as launch-scoped so containment cannot silently relaunch or reuse the active implicit browser. Upstream 0.32.0 owns request, worker, popup, and WebRTC containment and rejects CDP/auto-connect, profiles, restore/state replay, direct-page providers, iOS/Safari, and unsafe startup/profile Chrome args; the wrapper keeps only a final-URL policy check as defense in depth.

**Sessionless inspection and local commands:** Plain-text global help and version probes (`--help`, `-h`, `--version`, `-V`) must never allocate or bind the extension-managed session. The same session-ownership rule applies to read-only upstream `skills list`, `skills get …`, and `skills path …`, local auth profile management (`auth save/list/show/delete/remove`), plus local/setup surfaces such as `profiles`, `dashboard start/stop`, `device list`, `doctor`, `install`, `upgrade`, `session id`, `session info`, `session list`, and caller-owned local saved-state maintenance (`state list/show`, targeted `state clear <caller-owned-name>`, and `state rename`). Broad clear/clean and managed-state targets remain syntactically sessionless but are rejected by the pre-spawn managed-state boundary. The same boundary rejects any discovered or explicit upstream config for browser-backed native calls without reading it, pins an empty private config for accepted browser-backed spawns to close config-creation races, and rejects browser access to `.agent-browser` local storage through command-specific input/output operands (including dash-prefixed values), their path-bearing environment mirrors (state/profile/config, executable/extension/init-script, action-policy, artifact, skills, and socket paths), encoded, nested-file-scheme, Windows-aliased, or symlinked paths (including nonexistent descendants of symlinked directories), protected top-level `outputPath`, content-returning local-URL calls, any follow-up on a local file page, and persisted unverified top-level or batch tab/attachment/script/state-load transitions, and recursively inspected raw batch command strings. Electron launch handoff, status/probe reads, and capture from a tracked protected target use the same guard; snapshot/tabs handoff and status/probe reads verify the live URL before tab/title/content helpers, while handoff failure or cancellation closes the managed session and host process/profile. Raw artifact destinations use the same command parser as preparation and are checked before it creates parent directories. Enabled `--allow-file-access` argv/env and raw Chrome file-access or protected-path values are rejected; every upstream spawn clears `AGENT_BROWSER_ARGS`, removes caller file-access occurrences, and adds canonical `--args "" --allow-file-access false` defaults so project/user config cannot override the boundary while a validated safe CLI `--args` value remains usable. Post-transition summaries, including forced live probes after arbitrary `eval`, verify URL before reading title and fail an implicit transition that lands on a local file page. Failed/unexecuted navigation stays unverified, stale completions serialize authoritative state only, and replay treats unknown state as dominant over inconsistent target/ref fields. `get url`, `tab list`, non-content `tab <id>` selection, explicit safe HTTP(S) navigation away, and close remain available; tab selection stays unverified until `get url` succeeds. `session list` and `state list` remove wrapper-managed rows, and explicit `piab-*` live-session targets require an ownership record from the current extension instance. Non-plain-text sessionless commands still run with `--json` for machine-readable output, but the planner does not prepend the implicit managed `--session`, so an agent can inspect local capabilities or start/stop the standalone dashboard without consuming the implicit session slot before a real `open`. Browser-backed, context-dependent, or incomplete commands such as root `session`, untargeted `state clear`, bare `state clean`, `auth login`, `state save`, and `state load` keep normal managed-session injection. Command-shape allowlisting lives in `extensions/agent-browser/lib/command-policy.ts` (`needsManagedSession`), while `extensions/agent-browser/lib/runtime.ts` (`isPlainTextInspectionArgs`, `buildExecutionPlan`) applies that decision to execution planning.

A successful unnamed `sessionMode: "fresh"` launch should become the new extension-managed session so later default calls follow that browser instead of silently snapping back to the older managed session.

When a managed implicit or fresh `--session` plan reaches process execution, `details.managedSessionOutcome` summarizes the managed-session transition: on **success**, statuses such as `created`, `replaced`, `unchanged`, or `closed` describe what became current (including successful close commands: `close`, `quit`, or `exit`); on **failure** (launch error, timeout, missing binary, failed close command, and similar), `preserved` vs `abandoned` captures whether a prior managed session stayed current or no managed session ended up active, plus related names and booleans. Post-launch failures after the fresh browser has already opened the target page—such as **`qa`** reclassification, a later failed `job`/batch step, or a fresh batch timeout with recovered current-page evidence—preserve that fresh session as current and set the visible recovery text to say the fresh launch became current instead of reverting the agent to the old session. Failing calls that used `sessionMode: "fresh"`, plus otherwise-successful replacements whose automatic old-session close failed, append a short `Managed session outcome: …` line to model-visible text so the next default `sessionMode: "auto"` hop and any retained cleanup ownership are obvious; `"auto"` failures may still populate the struct without that extra line. Implementation and field semantics live in `extensions/agent-browser/lib/session-page-state.ts` and `extensions/agent-browser/lib/orchestration/browser-run/session-state.ts`; agent contract in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details); checklist row `RQ-0077` in [`SUPPORT_MATRIX.md`](SUPPORT_MATRIX.md).

## Preferring the native tool

Keep the handling simple:
- prefer the native tool through extension guidance and tool-call guards
- do not rely on package skill overrides as the primary solution

This keeps the product centered on native tool usage instead of auxiliary skill wiring.

Upstream restore-state persistence remains upstream-owned. The wrapper passes an explicit `AGENT_BROWSER_AUTOSAVE_INTERVAL_MS` through unchanged and may set `AGENT_BROWSER_RESTORE` for wrapper-owned managed sessions as described above. When no interval is set, wrapper-owned headed launches use `0` to avoid upstream 0.33.2's visible temporary multi-origin collector tabs and daemon-lock delays; the owned managed-session record persists that choice across every helper and follow-up subprocess, still-owned off-current session, Electron cleanup close, and transcript reload/resume so upstream never sees per-call daemon-configuration drift. Headless and caller-owned launches retain upstream's 30-second default. `0` preserves native close saves, but upstream exempts headed browsers from idle shutdown, so direct window close can lose changes since the last save. Because upstream reads the interval when its daemon starts, a nonzero explicit value cannot change an already-running wrapper-owned headed daemon; the wrapper preserves the recorded policy and requires close plus a fresh launch. The wrapper must not duplicate that timer or treat upstream restore files as wrapper-owned artifacts.

## Responsibility split

### `pi-agent-browser-native` owns

- tool registration and schema (including the optional `semanticAction` compilation path to upstream `find` or `select`)
- subprocess execution and JSON parsing through `buildAgentBrowserProcessEnv` in `extensions/agent-browser/lib/process.ts`: copies the parent process environment so user-approved provider credentials and other runtime variables reach upstream, then applies wrapper overrides such as the managed socket directory and clamped default operation timeout
- clear missing-binary errors
- compact result summaries, including presentation-time redaction: stateful browser-context commands (`auth`, `cookies`, `storage`, `dialog`, `frame`, `state`) use field-aware value redaction and compact formatters, while other structured upstream JSON (for example `network`, `diff`, `trace` / `profiler` / `record`, `console` / `errors` / `highlight` / `inspect` / `clipboard`, `stream`, `dashboard`, and `chat`) is passed through `redactPresentationData` in `extensions/agent-browser/lib/results/presentation.ts` so model-facing `details.data` and batch roll-ups stay compact and do not echo bearer tokens, proxy passwords, or similar fields verbatim; `redactInvocationArgs` in `extensions/agent-browser/lib/runtime.ts` masks trailing values for sensitive global flags such as `--body`, `--headers`, `--password`, and `--proxy`, preserves positional rules for `cookies set` and `storage local|session set`, and nested `batch` steps use the same argv and error-body scrubbing before echoing commands or errors
- bounded machine-readable outcome metadata on tool `details` (`resultCategory`, `successCategory`, `failureCategory`, optional `nextActions`, optional `pageChangeSummary` with per-step summaries on `batch`, optional `artifactVerification` with the same shape on each successful `batchSteps[]` row) so agents can branch without parsing prose; enums, classifier precedence, and generic follow-up payloads are implemented under `extensions/agent-browser/lib/results/` in focused modules (`contracts.ts` for shared types, `categories.ts` for `classifyAgentBrowserSuccessCategory` / `classifyAgentBrowserFailureCategory` / `buildAgentBrowserResultCategoryDetails`, `action-recommendations.ts` for `buildAgentBrowserNextActions`, `next-actions.ts` for the `AgentBrowserNextAction` shape and merge helpers, `recovery-actions.ts` for recovery id registries and `buildRecoveryNextActions`, `network.ts` for `classifyNetworkRequestFailure` / `summarizeNetworkFailures`, and related helpers). Per-session tab target, `refSnapshot` alignment, invalidation, and tab pinning observations flow through `extensions/agent-browser/lib/session-page-state.ts` from `extensions/agent-browser/index.ts`. Compact page-change summaries and artifact verification rollups are built in `extensions/agent-browser/lib/results/presentation.ts` (`buildPageChangeSummary`, `buildArtifactVerificationSummary`), and the human contract lives in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details). Real Pi custom tools otherwise only mark a row failed when `execute` throws, so the extension also registers `pi.on("tool_result", …)` and patches `agent_browser` results whose `details.resultCategory` is `failure` to set `isError: true`. Prose results also receive a short category notice, while caller-requested `--json` results with parseable JSON content keep that text unchanged so JSONL transcripts, UI affordances, and the machine-readable contract stay aligned for wrapper-side reclassifications such as `qa-failure` (`buildAgentBrowserToolResultPatch` in `extensions/agent-browser/lib/pi-tool-rendering.ts`; transcript semantics in the same contract doc)
- inline screenshots/images for the plain `screenshot` command; other image-like saves (for example `diff screenshot`) still appear in `details.artifacts` and summaries but are not auto-inlined as Pi image attachments (see [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md#details))
- lightweight session convenience
- docs, including a repo-readable command reference that mirrors the blocked direct-binary help path closely enough for normal agent work

### Upstream `agent-browser` owns

- browser automation semantics
- command vocabulary
- session/profile behavior
- auth/profile mechanics
- feature evolution

### Upstream command surface and checked-in docs

The extension does not ship `agent-browser`, but it does ship maintainer-owned documentation that must stay aligned when upstream help text grows. That work splits into two checks with different responsibilities:

1. **Canonical baseline metadata** lives in `scripts/agent-browser-capability-baseline.mjs` (target version, which `agent-browser` help invocations to sample in live checks, and which literal tokens must appear in upstream help and in human-written `docs/COMMAND_REFERENCE.md` inventory sections). That file does not execute `agent-browser`; rebasing it is an explicit edit after comparing real `--help` output from the installed binary.

2. **Generated Markdown blocks** in `docs/COMMAND_REFERENCE.md` are bounded by stable HTML comments. `scripts/check-command-reference-baseline.mjs` renders those blocks from the baseline metadata only. Use `npm run docs -- command-reference check` or `npm run docs -- command-reference write` after baseline edits so checked-in blocks cannot drift silently.

3. **Live help verification** is `scripts/verify-command-reference.mjs`, invoked via `npm run verify -- command-reference` (and included in the default `npm run verify` gate). It runs the baseline’s help commands against `agent-browser` on `PATH` and fails when the installed upstream surface does not match the declared target version or expected tokens.

This mirrors the playbook contract pattern described in [`TOOL_CONTRACT.md`](TOOL_CONTRACT.md): canonical TypeScript source and Markdown fragments stay paired through `npm run docs` / `npm run verify`, with deeper step-by-step notes in [`AGENTS.md`](https://github.com/fitchmultz/pi-agent-browser-native/blob/main/AGENTS.md), release checklist items in [`RELEASE.md`](RELEASE.md), and the baseline inventory-to-gates matrix in [`SUPPORT_MATRIX.md`](SUPPORT_MATRIX.md).

## Not the right design

V1 should avoid:
- a wide family of bespoke browser tools
- compatibility layers for old `agent-browser` versions
- deep embedded SDK-style integration
- embedding a human-browsable browser UI inside `pi`
- a slash-command-heavy UX

## V1 priorities

### Must have

- one native `agent_browser` tool
- direct `--json` execution
- optional stdin support
- implicit-session convenience
- screenshot/image attachment
- clear install and missing-binary messaging
- solid docs

### Nice to have

- compact renderers for snapshots and tab lists
- lightweight status display

## Summary

The architecture should stay:
- thin
- latest-only
- close to upstream
- native where it matters
- low-maintenance