feat(browser): import sessions and add agent PiP

docs/features/agent-browser-pip/tasks.md

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+# Agent Browser Surfaces and Picture-in-Picture Tasks
+
+## Status
+
+V1 read-only mirror revision implemented. Visible browser multi-tabs, Fit-desktop emulation, and
+packaged cross-platform validation remain open.
+
+## Completed Discovery
+
+- [x] Trace current YoBrowser page, native view, CDP, overlay, panel, and session lifecycles.
+- [x] Identify the unconditional Agent `browser.open.requested` panel-opening behavior.
+- [x] Confirm the current model is one page per session with no user/Agent ownership.
+- [x] Locate stable `LoopRun.runId` ownership and the missing tool-context propagation.
+- [x] Verify Electron View/WebContentsView reparenting and child-window platform constraints.
+- [x] Define the single-parent invariant, eligibility predicate, interaction matrix, and failure
+      behavior.
+- [x] Diagnose the current 420-520 px panel constraints, fixed Browser toolbar, native viewport
+      behavior, and stale hard-coded Chromium user-agent version.
+- [x] Write the proposal, implementation plan, feasibility assessment, and acceptance criteria.
+
+## Product Decisions Required Before Implementation
+
+- [x] Automatically switch an already open Workspace surface to Browser for each new Agent browser
+      action, without pinning Browser afterward.
+- [x] Confirm PiP **Close** dismisses only the current run and never closes the Agent page.
+- [x] Confirm one primary Agent page is retained per session and reused across loops.
+- [x] Confirm PiP remains eligible while the renderer session remains in the working state.
+- [x] Use a compact Agent-browser activity strip instead of a webpage below the usable PiP size.
+- [ ] Confirm Responsive default, explicit Fit desktop, and Browser Expand as the page-adaptation
+      model.
+- [x] Confirm undersized chats use a compact Agent activity strip instead of an unusable page card.
+- [x] Confirm PiP is a low-frame-rate read-only mirror with a 1280 x 800 background viewport.
+- [ ] Supply the referenced screenshot or approve a visual baseline for radius, shadow, toolbar,
+      sizing, and placement.
+
+## Phase 1: Run Identity and Workspace Foundation
+
+- [x] Add `runId` to internal tool execution options.
+- [ ] Thread `runId` through immediate, batch, resumed, and deferred tool paths.
+- [x] Pass `runId` through `AgentToolManager` into `YoBrowserToolHandler`.
+- [ ] Add an idempotent browser run-finalization port for every terminal outcome.
+- [ ] Replace per-session single-page state with workspace/tab state.
+- [x] Add explicit user/Agent page ownership and last-touched run identity.
+- [ ] Reuse one primary Agent tab per session and define popup inheritance.
+- [x] Expand shared browser status/events for ownership and run identity.
+- [x] Add runtime tests for ownership and run-sensitive placement.
+
+## Phase 2: Placement Ownership and Panel Tabs
+
+- [ ] Add a versioned renderer layout report for conversation and panel bounds.
+- [ ] Validate layout sender, host window, and active session in main.
+- [ ] Add one serialized placement controller per workspace.
+- [ ] Enforce panel/PiP/detached single-parent invariants.
+- [ ] Remove direct competing attach/detach ownership from `BrowserPanel.vue`.
+- [ ] Add browser tab create/select/close operations.
+- [ ] Add a compact panel tab strip and Agent marker using existing UI primitives.
+- [ ] Add container-responsive wide, compact, and narrow Browser chrome.
+- [ ] Keep the address bar usable and every hidden command keyboard-accessible at 420 px.
+- [x] Generalize the existing Workspace fullscreen shell behavior into Browser Expand/Restore.
+- [x] Derive the YoBrowser desktop user-agent Chromium version from the runtime.
+- [x] Route user navigation and Agent tools through explicit page ownership.
+- [x] Stop destroying a completed Agent page merely because the session becomes inactive.
+- [ ] Remove the compatibility single-page status/routes after all callers migrate.
+- [ ] Add main/renderer tests for tab and placement races.
+
+## Phase 3: Page Presentation, PiP Surface, and Interaction
+
+- [ ] Build representative responsive/fixed-width website fixtures.
+- [ ] Compare device emulation and controlled zoom for per-tab Fit desktop.
+- [ ] Verify user input, CDP input, DOM, screenshot, iframe, fixed/sticky, and reset coordinates.
+- [ ] Ship Fit desktop only if one path passes the complete coordinate proof.
+- [ ] Add per-tab Responsive/Fit presentation state without restart persistence.
+- [x] Replace the native-page PiP with a lazy Canvas mirror.
+- [x] Add the focusless render host and explicit `capturing`/`rendering`/`stopped` modes.
+- [x] Add bounded capture, resize, encoding, and typed in-memory frame delivery.
+- [x] Keep preview chrome in the trusted chat renderer and expose only typed mode/frame contracts.
+- [x] Render sanitized title, Agent activity, **Open in panel**, and **Close**.
+- [x] Implement the V1 eligibility predicate.
+- [x] Remove the unconditional Agent-triggered `sidepanelStore.openBrowser()` behavior.
+- [x] Implement default responsive bounds and small-region fallback.
+- [x] Implement compact Agent activity-strip fallback below usable page size.
+- [x] Make every non-button PiP point draggable and distinguish click from drag by threshold.
+- [x] Toggle the close/expand toolbar on a non-drag click without forwarding page input.
+- [x] Implement current-run dismissal without page/tool interruption.
+- [x] Implement panel handoff with no reload or duplicate display.
+- [x] Move the Agent page to the 1280 x 800 render host when Browser hides during an active run.
+- [x] Keep panel activity overlay behavior and render the PiP activity halo in trusted Canvas chrome.
+- [x] Add accessible labels, focus behavior, and i18n strings.
+- [x] Add focused tests for mirror eligibility, frame retention, input isolation, dismissal, drag,
+      focus, and panel handoff.
+
+## Phase 4: Lifecycle and Cross-Platform Validation
+
+- [ ] Test loop fail, abort, supersede, and teardown cleanup.
+- [x] Test loop completion cleanup.
+- [ ] Test permission/question pause behavior.
+- [ ] Test session switch, route change, multi-window activation, and stale events.
+- [x] Test focus/blur mode transitions and host-focus isolation.
+- [ ] Test show/hide, minimize/restore, resize, maximize, and display scale.
+- [ ] Test tab close and page/chrome/host crash recovery.
+- [ ] Test concurrent user commands and Agent tool activity.
+- [ ] Test page input, chat focus, native z-order, and activity overlay on macOS.
+- [ ] Test Browser chrome at every container breakpoint and at non-integer display scales.
+- [ ] Test Responsive, Fit desktop if approved, Expand, and Restore without page reload/state loss.
+- [ ] Repeat packaged focus/z-order/drag tests on Windows and Linux.
+- [ ] Verify the exact page WebContents/CDP identity survives every placement move.
+- [ ] Verify no inactive-session content appears, including transient frames.
+- [ ] Profile retained Agent-tab memory before considering eviction.
+- [x] Run `pnpm run format`.
+- [x] Run `pnpm run i18n`.
+- [x] Run `pnpm run lint`.
+- [x] Run typecheck, build, focused suites, and the full main/renderer test suite.
+- [ ] Capture BEFORE/AFTER screenshots or GIFs and include the ASCII layouts in the PR.
+
+## Deferred Work
+
+- [ ] Persist PiP position/size only if users demonstrate a need.
+- [ ] Add a measured idle Agent-tab eviction policy only if memory profiling requires it.
+- [ ] Add keyboard PiP movement if accessibility review requires it.
+- [ ] Generalize Agent tools to explicit tab IDs only when multi-tab automation is requested.
+- [ ] Share architecture with standalone browser windows only after a separate convergence design.