feat: pin the agent to a chosen browser profile (#16)

* feat: pin the agent to a chosen browser profile (#15)

Harness tabs were created with a bare Target.createTarget, which places
them in Chrome's defaultBrowserContextId — and that value follows window
focus. Which profile the agent acted as therefore depended on which
browser window the user last clicked, so the same task could run as a
work account on one run and a personal account on the next.

/browser-profile lists the connected browser's profiles as "Name (email)"
and pins one to ~/.pi/agent/browser-harness.json, so the choice outlives
the session. The same picker appears on first browser_setup when nothing
is pinned; with no interactive UI, or on cancel, setup continues with a
note and the previous behavior.

Chrome offers no direct route to another profile: Target.createTarget
rejects a foreign browserContextId, and openerId does not inherit the
opener's context. The window is opened through the browser's own command
line (--profile-directory, handed to the running browser by Chromium's
ProcessSingleton) and identified by a unique file:// sentinel page, since
a bare about:blank#token argument is discarded. Further tabs come from
window.open evaluated with userGesture: true — the only CDP-reachable way
to place a tab in a non-default browser context — correlated by a unique
token so concurrent isolated tabs stay distinct. A failed handshake is
reported, never silently redirected to another profile.

All four tab-creation sites now funnel through cdp/target-factory, so
open_urls and the isolated tabs behind web_search / read_page cannot run
with a different profile's cookies than the visible tabs.

Also fixed along the way: snap Chromium is discovered, Windows uses
%LOCALAPPDATA%, browsers launched with an explicit --user-data-dir are
found, the running browser is chosen by ranking candidates against the
connected user-data-dir rather than taking the first process found, and
an installed-but-closed browser no longer reads as running.

CI runs the profile suites and a real-browser end-to-end test on ubuntu,
macOS, and Windows — profile discovery is the one part of the harness
whose behavior genuinely differs per OS.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix: single-flight harness window creation

Isolated tabs run concurrently (browser_read_page is registered
unserialized), so several could each find "no harness window" and create
one — two blank windows before this feature, two LAUNCHED profile windows
after it. ensureHarnessWindow now shares one in-flight creation per
client.

Sharing introduces a second hazard: freshlyCreated is a claim on the seed
tab, and if every waiter received it, they would all drive the same tab.
Only the caller that started the creation keeps the claim; the rest open
their own tab beside it.

Covered by test/manual/profile-concurrency-test.ts (five concurrent
isolated tabs, pinned and unpinned: distinct targets, one window, correct
profile), wired into CI on Linux only — the coordination is pure JS and
identical across platforms.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix: tilde expansion differs by purpose on Windows

CI on windows-latest caught this: join("~", "x") yields "~\x" there, and
expandTilde only handled "~/".

The two uses are not the same, so they no longer share a helper. The
agent dir stays byte-compatible with pi's own expandTildePath ("~/" only,
every platform) — being more lenient would put the pin file somewhere pi
never looks. $CHROME_USER_DATA_DIR is ours to interpret, so it accepts
"~\" as well, which is what a Windows user would type.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/test/profile/store-test.ts b/test/profile/store-test.ts
new file mode 100644
index 0000000..c881372
--- /dev/null
+++ b/test/profile/store-test.ts
@@ -0,0 +1,116 @@
+/**
+ * Unit tests for the profile pin store — no browser required.
+ *
+ * Redirects pi's agent dir via $PI_CODING_AGENT_DIR so the real
+ * ~/.pi/agent/browser-harness.json is never touched.
+ *
+ * Run: npx tsx test/profile/store-test.ts
+ */
+import { mkdtempSync, mkdirSync, readdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+let passed = 0;
+let failed = 0;
+const check = (cond: boolean, label: string): void => {
+  if (cond) {
+    passed++;
+    console.log(`  ✓ ${label}`);
+  } else {
+    failed++;
+    console.error(`  ✗ ${label}`);
+  }
+};
+
+const pin = {
+  userDataDir: "/home/u/.config/google-chrome",
+  profileDir: "Profile 1",
+  label: "Aman (aman@example.com)",
+  savedAt: new Date(0).toISOString(),
+};
+
+async function main(): Promise<void> {
+  const sandbox = mkdtempSync(join(tmpdir(), "pi-pin-test-"));
+  process.env["PI_CODING_AGENT_DIR"] = sandbox;
+
+  // Imported after the env override so paths.ts resolves into the sandbox.
+  const { pinFilePath } = await import("../../src/profile/paths");
+  const { readPin, writePin, clearPin } = await import("../../src/profile/store");
+
+  // P1: agent dir honours the env override
+  check(pinFilePath() === join(sandbox, "browser-harness.json"), "P1: pin path follows $PI_CODING_AGENT_DIR");
+
+  // P2: nothing written yet
+  check((await readPin()) === null, "P2: absent file reads as no pin");
+
+  // P3: round trip
+  {
+    const written = await writePin(pin);
+    check(written.success, "P3: write succeeds");
+    const read = await readPin();
+    check(read?.profileDir === "Profile 1", "P3: profileDir round-trips");
+    check(read?.userDataDir === pin.userDataDir, "P3: userDataDir round-trips");
+    check(read?.label === pin.label, "P3: label round-trips");
+  }
+
+  // P4: no temp files survive an atomic write
+  check(readdirSync(sandbox).filter((f) => f.endsWith(".tmp")).length === 0, "P4: write leaves no .tmp files");
+
+  // P5: overwrite replaces rather than appends
+  {
+    await writePin({ ...pin, profileDir: "Default", label: "Work (work@example.com)" });
+    const read = await readPin();
+    check(read?.profileDir === "Default", "P5: second write replaces the first");
+    check(readdirSync(sandbox).filter((f) => f === "browser-harness.json").length === 1, "P5: one pin file on disk");
+  }
+
+  // P6: clear
+  {
+    const cleared = await clearPin();
+    check(cleared.success, "P6: clear succeeds");
+    check((await readPin()) === null, "P6: cleared pin reads as none");
+  }
+
+  // P7: corrupt file degrades to no pin
+  writeFileSync(pinFilePath(), "{ not json at all", "utf8");
+  check((await readPin()) === null, "P7: malformed JSON reads as no pin");
+
+  // P8: unknown schema version is not guessed at
+  writeFileSync(pinFilePath(), JSON.stringify({ version: 99, profile: pin }), "utf8");
+  check((await readPin()) === null, "P8: future version reads as no pin");
+
+  // P9: structurally invalid pin is rejected
+  writeFileSync(pinFilePath(), JSON.stringify({ version: 1, profile: { profileDir: 42 } }), "utf8");
+  check((await readPin()) === null, "P9: wrong field types read as no pin");
+
+  // P10: a missing agent dir is created on write
+  {
+    rmSync(sandbox, { recursive: true, force: true });
+    const written = await writePin(pin);
+    check(written.success, "P10: write recreates a missing agent dir");
+    check((await readPin())?.profileDir === "Profile 1", "P10: pin readable after dir recreation");
+  }
+
+  // P11: an unwritable location surfaces as an error result, not a throw
+  {
+    const blocked = join(sandbox, "blocked");
+    mkdirSync(blocked, { recursive: true });
+    writeFileSync(join(blocked, "browser-harness.json"), "{}", "utf8");
+    // Point the agent dir at a FILE — mkdir/write must fail cleanly.
+    process.env["PI_CODING_AGENT_DIR"] = join(blocked, "browser-harness.json");
+    const { writePin: writeAgain } = await import(`../../src/profile/store?nocache=${Date.now()}`);
+    const written = await writeAgain(pin);
+    check(!written.success, "P11: write into an invalid dir returns an error result");
+    process.env["PI_CODING_AGENT_DIR"] = sandbox;
+  }
+
+  rmSync(sandbox, { recursive: true, force: true });
+
+  console.log(`\n${passed} passed, ${failed} failed`);
+  process.exit(failed === 0 ? 0 : 1);
+}
+
+main().catch((e) => {
+  console.error("profile store test failed:", e);
+  process.exit(1);
+});