feat: add dedicated subagent view to TUI

[avoidwork]

Description

Adds a dedicated SUBAGENTS panel to the TUI that captures and renders each subagent's reasoning, message segments, and tool calls separately from the orchestrator's conversation. callProvider now captures the stream namespace so subagent subgraphs emit distinct subagent_* event types, which are routed to a dedicated subagent store keyed by namespace instead of the orchestrator's assistant bubble.

Also fixes two related issues surfaced while building the panel: view-switching slash commands (/subagents, /skills, /memories, etc.) no longer interrupt an in-flight stream, and the ConversationArea stays mounted across panel views so message list and session state survive the round-trip.

Type of Change

• New feature (non-breaking change which adds functionality)
• Bugfix (non-breaking change which fixes an issue)

Testing

Added tests/unit/tui/subagentsPanel.test.js (16 tests) covering namespace discrimination, event routing, and tool-call redirection. Added tests/unit/tui/repro-subagents-escape.test.js for the Escape-to-conversation behavior. Updated tests/unit/tui/panels.test.js, tests/unit/tui.test.js, and tests/unit/tui/commandParser.test.js for the new SUBAGENTS panel and isViewCommand helper. Verified with npm run test (4219 passing), npm run lint (0 errors), and npm run coverage (subagentStore.js at 100% line coverage).

Coverage

• Line coverage maintained

Checklist

• npm run lint passes
• Tests pass with maintained line coverage
• No forbidden patterns used
• Conventional Commit style applied

Closes #1360

[avoidwork]

Audit Results — tui-subagents-panel

Goal Fulfillment

Goal	Status	Notes
1. Capture namespace in callProvider	✅ Complete	index.js captures namespace, computes isSubagent = namespace.length > 0, emits subagent_message/subagent_reasoning/subagent_tool/subagent_tool_start/subagent_tool_end for subagents; root graph events unchanged.
2. Route subagent events in TUI	✅ Complete	createStreamingHandler routes subagent_* events to subagentStoreRef.current via updateSubagentStore, returning early before touching streamingMsgIdRef.current.
3. Add SUBAGENTS panel	✅ Complete	PANELS.SUBAGENTS added and registered in getPanelOrder(); src/tui/subagentsPanel.js created reusing MessageBubble.
4. Wire panel into App	✅ Complete	currentView === PANELS.SUBAGENTS branch added, passing subagentStore from conversationAreaRef.current?.getSubagentStore?.().
5. Write unit tests	✅ Complete	tests/unit/tui/subagentsPanel.test.js covers namespace discrimination, event routing, and tool-call redirection.
6. Verify	✅ Complete	npm run test (4214 pass), npm run lint (0 errors), npm run coverage (maintained; new files 100% line coverage).

Spec Compliance

• tui-subagents-panel spec — All ADDED requirements satisfied: subagent store keyed by namespace, segments for message/reasoning/tool, tool-call tracking.
• tui-streaming delta spec — MODIFIED requirement satisfied: createStreamingHandler routes subagent_message/subagent_reasoning/subagent_tool_start/subagent_tool_end to the subagent store, not streamingMsgIdRef.current; root graph events continue to update the assistant bubble.

Task Completion

All 8 tasks in tasks.md are marked [x]. openspec status reports isComplete: true.

Quality Check

• No forbidden patterns (no console.log, no empty catch, no wildcard exports).
• New modules (subagentStore.js, subagentsPanel.js) are pure/testable and follow project conventions (2-space indent, JSDoc, camelCase).
• Existing panels.test.js and tui.test.js updated to reflect the new panel order (7 panels).
• npm start reaches the Ink mount but fails on raw-mode stdin — an environment limitation of the non-TTY sandbox, not a code defect.

Iterations

• Spec audit: 1 iteration (no errors found).
• Implementation audit: 1 iteration (no errors found).

[avoidwork]

Subagent event routing — namespace discriminator

This PR routes subagent activity to a dedicated SUBAGENTS store. The discriminator that separates orchestrator events from subagent events lives in callProvider (index.js), and it took a couple of iterations to get right. Documenting the final logic here for future reference.

The namespace structure (with subgraphs: true)

Source	Namespace	Length
Orchestrator message	["model_request:<uuid>"]	1
Orchestrator tool call	["tools:<id>"]	1
Subagent message	["tools:<id>", "model_request:<uuid>"]	2
Subagent tool call / result	["tools:<id>", "tools:<subid>"]	2

The rule

const isSubagent =
  Array.isArray(namespace) &&
  namespace.length > 1 &&
  namespace.some((part) => part.startsWith("tools:"));

A namespace is subagent-scoped only when it has a tools: segment and more than one segment. The orchestrator's own tool calls are emitted under a single tools: segment (length 1), so they stay in the conversation view. A subagent subgraph always adds a second segment (a nested model_request: or tools:), so it routes to the SUBAGENTS store.

Why not a UUID match?

There is no stable programmatic orchestrator identifier. The ReactAgent exposes no id/uuid attribute — its own keys are options and compactContext, and its prototype exposes graph, checkpointer, store, invoke, stream, etc. The model_request:<uuid> in the namespace is a per-request model ID, not a persistent orchestrator identity. So the discriminator is structural (namespace shape), not a UUID match.

History of the fix

1. Initial: namespace.length > 0 — wrong. The root graph yields ["model_request:<uuid>"] (length 1), so the orchestrator's own messages were misrouted as subagent activity.
2. Second attempt: namespace.some(part => part.startsWith("tools:")) — still wrong. The orchestrator's own tool calls are emitted under ["tools:<id>"], so they were misrouted too.
3. Final: namespace.length > 1 && namespace.some(part => part.startsWith("tools:")) — correct. Verified empirically against the orchestrator's ls/task tool calls and subagent message/tool-call namespaces.

All 4215 tests pass; lint is clean.