fix(workspace): support jump and auto-follow in agent terminal views

[Juliusolsson05]

Summary

Fixes #837.

Jump to Latest, Auto-follow Focused Agent, and Tail All now operate on raw agent terminal viewports, including OpenCode Terminal and Claude/Codex terminal views, without switching into the rendered feed. Plain shell panes remain excluded.

Implementation

• Preserve the existing jump counter and follow flags; mask forced follow by composed pane visibility.
• Pin after asynchronous PTY writes and attach replay finish parsing, with fire-time state/lifetime checks.
• Coalesce and defer scroll-event re-pins to respect real xterm viewport reentrancy.
• Use public xterm markers to restore retained content after follow ends. Markers track scrollback trimming; evicted anchors fall back to the oldest retained normal-buffer line.
• Reset saved state on session changes; clean up markers/listeners and display TAIL status on raw views.
• Update palette and external-control descriptions without changing schemas or persisted data. No migration is required.

Review

One Claude and one Codex reviewer ran through Agent Code MCP orchestration. Both initially requested fixes. Deferred-write races, replay timing, reentrant scrolling, trim drift, session-state leakage, and a tautological command test were corrected. Both independently approved integrated revision 25eabfc with no remaining blocker. These are agent reviews, not GitHub account approvals.

Verification

Node 24.14.1, fresh npm ci, origin/main integrated and submodules updated.

• Typecheck passed.
• Targeted renderer suite: 30 tests passed across follow, submit, dimension ownership, and command guards.
• Full renderer: 563 passed across 129 files, using --maxWorkers=4 --testTimeout=15000 for local cold-transform load.
• Full system: 111 passed across 17 files, including the new real Electron/xterm test.
• Real-engine regression proves re-pin, jump, restoration after trimming, eviction fallback, alternate-buffer handling and marker disposal. Before the fix it restored line-1191 instead of line-1091 after trimming; public markers made it pass.
• Full unit: 2206 passed, one local image-fixture provenance test failed because a cited historical private session no longer exists. This unrelated local source-retention issue is tracked in test(media): make image fixture provenance checks survive local transcript rotation #839; no fixture, citation or assertion was weakened.
• Test contract, keybinding check and git diff --check passed.
• Earlier Node 25 runs and one timed-out combined run are not claimed as passing verification. CI results on this exact head are the merge gate.

Limits

Raw follow controls xterm scrollback, not an alternate-screen TUI internal history/keybindings. If anchored content is evicted or removed during reflow, restore falls back to the oldest retained line. No new provider, no plain-shell follow, no shared-checkout changes.

The user explicitly authorized merge after Claude/Codex review. Merge remains gated on passing CI; no bypass or auto-merge requested.

[Juliusolsson05]

Delivery complete: both reviewers approved 25eabfc, then quality-gate (10m19s) and minimum-node-fixture-gate (47s) passed on that exact head. CI covered typechecks, core/system/renderer tests, coverage, and distributable verification. Merged with an exact-head fence under the user explicit review-then-merge authorization; merge commit 31e81ef. Issue #837 closed via this PR. Local main was fast-forwarded without altering the unrelated untracked user plan. The separate local source-retention test issue remains tracked in #839.