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, 130 insertions, 0 deletions

diff --git a/test/profile/paths-test.ts b/test/profile/paths-test.ts
new file mode 100644
index 0000000..1a2c937
--- /dev/null
+++ b/test/profile/paths-test.ts
@@ -0,0 +1,130 @@
+/**
+ * Unit tests for path resolution — runs on Linux, macOS, and Windows in CI.
+ *
+ * Only the branch for the host platform can be exercised, so each assertion is
+ * guarded by process.platform; the CI matrix is what gives all three coverage.
+ *
+ * Run: npx tsx test/profile/paths-test.ts
+ */
+import { homedir } 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(`  ✗ ${label}`);
+  }
+};
+
+/** Re-import with a fresh module identity so env changes are picked up. */
+const freshImport = async (): Promise<typeof import("../../src/profile/paths")> =>
+  import(`../../src/profile/paths?cache=${Math.random()}`);
+
+const withEnv = async (key: string, value: string | undefined, fn: () => Promise<void>): Promise<void> => {
+  const saved = process.env[key];
+  if (value === undefined) delete process.env[key];
+  else process.env[key] = value;
+  try {
+    await fn();
+  } finally {
+    if (saved === undefined) delete process.env[key];
+    else process.env[key] = saved;
+  }
+};
+
+async function main(): Promise<void> {
+  // A1: agent dir default and override
+  await withEnv("PI_CODING_AGENT_DIR", undefined, async () => {
+    const { agentDir, pinFilePath } = await freshImport();
+    check(agentDir() === join(homedir(), ".pi", "agent"), "A1: default agent dir is ~/.pi/agent");
+    check(pinFilePath() === join(homedir(), ".pi", "agent", "browser-harness.json"), "A1: pin file sits in it");
+  });
+  // pi's own expandTildePath only understands "~/" — never "~\" — so the agent
+  // dir must resolve identically or the pin lands where pi does not look.
+  await withEnv("PI_CODING_AGENT_DIR", "~/custom-agent", async () => {
+    check(
+      (await freshImport()).agentDir() === `${homedir()}/custom-agent`,
+      "A1: '~/' in the agent-dir override expands like pi",
+    );
+  });
+  if (process.platform === "win32") {
+    await withEnv("PI_CODING_AGENT_DIR", "~\\custom-agent", async () => {
+      check(
+        (await freshImport()).agentDir() === "~\\custom-agent",
+        "A1 win: '~\\' is left alone, matching pi's own resolution",
+      );
+    });
+  }
+
+  // A2: platform candidate list
+  await withEnv("CHROME_USER_DATA_DIR", undefined, async () => {
+    const dirs = (await freshImport()).userDataDirCandidates();
+    check(dirs.length > 0, "A2: candidates are non-empty on this platform");
+    check(new Set(dirs).size === dirs.length, "A2: candidate list is de-duplicated");
+
+    if (process.platform === "linux") {
+      check(dirs.includes(join(homedir(), ".config/google-chrome")), "A2 linux: Chrome stable dir present");
+      check(dirs.includes(join(homedir(), "snap/chromium/common/chromium")), "A2 linux: snap Chromium dir present");
+      check(dirs.includes(join(homedir(), ".config/BraveSoftware/Brave-Browser")), "A2 linux: Brave dir present");
+    } else if (process.platform === "darwin") {
+      const support = join(homedir(), "Library", "Application Support");
+      check(dirs.includes(join(support, "Google/Chrome")), "A2 macos: Chrome dir present");
+      check(dirs.includes(join(support, "BraveSoftware/Brave-Browser")), "A2 macos: Brave dir present");
+      check(dirs.includes(join(support, "Microsoft Edge")), "A2 macos: Edge dir present");
+    } else if (process.platform === "win32") {
+      const lad = process.env["LOCALAPPDATA"] ?? join(homedir(), "AppData", "Local");
+      check(dirs.includes(join(lad, "Google/Chrome/User Data")), "A2 win: Chrome dir derives from %LOCALAPPDATA%");
+      check(dirs.includes(join(lad, "Microsoft/Edge/User Data")), "A2 win: Edge dir present");
+    }
+  });
+
+  // A3: %LOCALAPPDATA% redirection is honoured (Windows-only behaviour)
+  if (process.platform === "win32") {
+    await withEnv("LOCALAPPDATA", "D:\\Redirected\\Local", async () => {
+      const dirs = (await freshImport()).userDataDirCandidates();
+      check(
+        dirs.some((d) => d.startsWith("D:\\Redirected\\Local") || d.startsWith("D:/Redirected/Local")),
+        "A3 win: redirected LOCALAPPDATA is used",
+      );
+    });
+  }
+
+  // A4: $CHROME_USER_DATA_DIR override leads the list. This value is ours to
+  // interpret, so both tilde separators are accepted.
+  await withEnv("CHROME_USER_DATA_DIR", join("~", "my-chrome-data"), async () => {
+    const dirs = (await freshImport()).userDataDirCandidates();
+    check(dirs[0] === join(homedir(), "my-chrome-data"), "A4: env override is first and tilde-expanded");
+  });
+  await withEnv("CHROME_USER_DATA_DIR", "~/my-chrome-data", async () => {
+    const dirs = (await freshImport()).userDataDirCandidates();
+    check(dirs[0] === join(homedir(), "my-chrome-data"), "A4: forward-slash tilde expands on every platform");
+  });
+
+  // A5: browser naming
+  {
+    const { browserNameForUserDataDir } = await freshImport();
+    check(browserNameForUserDataDir("/home/u/.config/google-chrome") === "Chrome", "A5: Chrome recognised");
+    check(
+      browserNameForUserDataDir("/home/u/.config/BraveSoftware/Brave-Browser") === "Brave",
+      "A5: Brave recognised",
+    );
+    check(
+      browserNameForUserDataDir("C:\\Users\\u\\AppData\\Local\\Microsoft\\Edge\\User Data") === "Edge",
+      "A5: Edge recognised through Windows separators",
+    );
+    check(browserNameForUserDataDir("/home/u/.config/chromium") === "Chromium", "A5: Chromium beats Chrome");
+  }
+
+  console.log(`\n${passed} passed, ${failed} failed`);
+  process.exit(failed === 0 ? 0 : 1);
+}
+
+main().catch((e) => {
+  console.error("profile paths test failed:", e);
+  process.exit(1);
+});