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, 19 insertions, 0 deletions

diff --git a/src/cdp/session.ts b/src/cdp/session.ts
index 03410ba..eeb3802 100644
--- a/src/cdp/session.ts
+++ b/src/cdp/session.ts
@@ -45,9 +45,21 @@ export type CdpSession = {
   drainConsoleBuffer(filter: ConsoleFilter): ConsoleDrainResult;
 };
 
+/**
+ * Supplies the seed tab when attachFirstPage finds no owned tab to attach to.
+ * Injected by the client so that seeding goes through the target factory —
+ * which, with a profile pinned, opens the window inside that profile. Without
+ * it, attachFirstPage's own `Target.createTarget` would land in whichever
+ * profile currently has focus.
+ *
+ * The provider is responsible for its own ownership bookkeeping.
+ */
+export type SeedTargetProvider = () => Promise<Result<string, CdpError>>;
+
 export const createCdpSession = (
   transport: CdpTransport,
   ownership?: OwnershipRegistry,
+  createSeedTarget?: SeedTargetProvider,
 ): CdpSession => {
   let sessionId: string | null = null;
   let targetId: string | null = null;
@@ -246,6 +258,13 @@ export const createCdpSession = (
         const ownedLive = ownership.list().filter((id) => allPages.some((p) => p.targetId === id));
         pickTargetId = ownedLive[0];
       }
+      if (!pickTargetId && createSeedTarget) {
+        // Delegated seeding (see SeedTargetProvider): the provider creates the
+        // window in the right profile and records ownership itself.
+        const seeded = await createSeedTarget();
+        if (!seeded.success) return seeded;
+        pickTargetId = seeded.data;
+      }
       if (!pickTargetId) {
         const createParams: Record<string, unknown> = { url: "about:blank" };
         if (ownership) createParams["newWindow"] = true;