fix Claude pane hang: cap tail, parse off-isolate, coalesce notifies

The native Claude pane (T-137) picks the newest transcript JSONL by
mtime — which on a live session is this multi-MB active file. On attach
it read and parsed the whole file synchronously on the UI isolate and
fired notifyListeners per item, freezing the app.

Three fixes: cap the initial read to a recent tail (256KB, injectable
for tests); run JSON parsing in a background isolate via Isolate.run;
coalesce the controller's notifications with a zero-duration Timer so a
burst collapses into one rebuild (a microtask-scheduled notify wouldn't
— stream events deliver one per microtask and the notify interleaves).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.pql/changelog/ticket_history/2026-05.sql

@@ -2140,3 +2140,4 @@ Refinement (2026-05-22, refinement-agent review):
 ---
 Findings (2026-05-22): docs/spikes/cc-team-internals-2.1.148.md. All 5 checks answered from real artifacts + tmux manual + synthetic control-mode test (no live run/quota). Key risk for T-139: pane->teammate->transcript identity joins only on agentType (config <-> .meta.json), ambiguous for same-type teammates -> needs joinedAt/mtime or lead-transcript tiebreaker. tmux 3.6a has no %pane-died; poll list-panes -a. Teammate transcripts at <munged>/<sid>/subagents/agent-<hex>.jsonl + .meta.json{agentType,description}.', NULL, '2026-05-22 17:55:11', '2026-05-22 17:55:11', '2026-05-22 17:55:11', NULL, 'dbf4f56d1ec9d2234f255826c5f88f68', 1) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-137', 'status', 'backlog', 'in_progress', NULL, '2026-05-22 17:58:07', '2026-05-22 17:58:07', '2026-05-22 17:58:07', NULL, '4e67262d4b04f8541e71fe8f03106fbf', 1) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-137', 'status', 'in_progress', 'done', NULL, '2026-05-22 18:14:32', '2026-05-22 18:14:32', '2026-05-22 18:14:32', NULL, 'a284c7249dda3c63a52a202bad07f105', 1) ON CONFLICT(hash) DO NOTHING;

.pql/changelog/tickets/2026-05.sql

@@ -2485,3 +2485,4 @@ Refinement (2026-05-22, refinement-agent review):
 ---
 Findings (2026-05-22): docs/spikes/cc-team-internals-2.1.148.md. All 5 checks answered from real artifacts + tmux manual + synthetic control-mode test (no live run/quota). Key risk for T-139: pane->teammate->transcript identity joins only on agentType (config <-> .meta.json), ambiguous for same-type teammates -> needs joinedAt/mtime or lead-transcript tiebreaker. tmux 3.6a has no %pane-died; poll list-panes -a. Teammate transcripts at <munged>/<sid>/subagents/agent-<hex>.jsonl + .meta.json{agentType,description}.', 'done', 'high', NULL, NULL, NULL, '2026-05-22 15:59:34', '2026-05-22 17:55:11', NULL, '2f9a445df8c60beafe126aff339410b8', 1) ON CONFLICT(id) DO UPDATE SET type=excluded.type, parent_id=excluded.parent_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);
 INSERT INTO tickets (id, type, parent_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-137', 'story', 'T-132', 'ConversationView + replace the terminal in the Claude pane', 'New lib/builtin/claude/src/conversation_view.dart rendering user / assistant(markdown via ClideMarkdown) / tool-call card / tool-result+diff card; whole tree under one SelectionArea. Swap ClidePtyView -> ConversationView in lib/builtin/claude/src/claude_pane.dart (~line 287). Claude still runs in tmux (detached / output ignored) but content comes from the transcript (TranscriptReader). Keep the terminal builtin + ClidePtyView for general use. Surface conversation as events too (D-6). Cite D-75. Acceptance: make run shows the native Claude conversation from the live transcript; select+copy across cards works; no terminal in the Claude pane; terminal builtin still works; widget tests. Blocked by T3, T4.', 'in_progress', 'high', NULL, NULL, NULL, '2026-05-22 15:59:34', '2026-05-22 17:58:07', NULL, 'e8244b90386314574545f0c1a7bd012c', 1) ON CONFLICT(id) DO UPDATE SET type=excluded.type, parent_id=excluded.parent_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);
+INSERT INTO tickets (id, type, parent_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-137', 'story', 'T-132', 'ConversationView + replace the terminal in the Claude pane', 'New lib/builtin/claude/src/conversation_view.dart rendering user / assistant(markdown via ClideMarkdown) / tool-call card / tool-result+diff card; whole tree under one SelectionArea. Swap ClidePtyView -> ConversationView in lib/builtin/claude/src/claude_pane.dart (~line 287). Claude still runs in tmux (detached / output ignored) but content comes from the transcript (TranscriptReader). Keep the terminal builtin + ClidePtyView for general use. Surface conversation as events too (D-6). Cite D-75. Acceptance: make run shows the native Claude conversation from the live transcript; select+copy across cards works; no terminal in the Claude pane; terminal builtin still works; widget tests. Blocked by T3, T4.', 'done', 'high', NULL, NULL, NULL, '2026-05-22 15:59:34', '2026-05-22 18:14:32', NULL, '6651a2c3c9099f7d38553f6cf9e41e98', 1) ON CONFLICT(id) DO UPDATE SET type=excluded.type, parent_id=excluded.parent_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);