feat(tui): issue #13 — §5 layout reshape + Tools pane (v0.4.0)

Reshape the TUI from vertical-stack single-pane to Horizontal
two-column with TabbedContent on the right; v1 has a single Tools
tab that consumes ToolStart/ToolResult SSE events previously
rendered inline in the transcript. Foundation for the rest of
design-brief §5; subsequent panes (Persona/AdminEvents/BifrostState/
ServerLog) plug in as sibling TabPanes when their substrate
blockers resolve.

Three coupled pieces, all in-place amendments to issues #4 + #12:

- **Layout**: compose() yields Horizontal#main-row containing
  Vertical#left-column (transcript + thinking-current + prompt) and
  Vertical#right-column (TabbedContent#side-panes with
  TabPane#tools-tab → RichLog#tools-log). Width split 2fr:1fr. CSS
  dock rules narrow to per-container scope so thinking-current
  toggling doesn't reflow the right column.
- **Tools pane**: TuiPresenterState.render() signature widens with
  tools_log: RichLog. ToolStart/ToolResult route there per INV-014;
  every other event keeps its issue-#12 routing. Plain-label
  fallback under render-exception preserves routing (INV-009).
- **Ctrl+1 binding + pane-name widget**: BINDINGS gains
  Binding("ctrl+1", "focus_tools") which programmatically sets
  TabbedContent.active; Textual's default preserves Input focus per
  INV-016 (test asserts; regression path documented).
  Static#pane-name in the footer renders "Tools" v1 (static — no
  tab-switch handler wiring lands in #13 per amendment-2 from
  Volva paraphrase review).

CLI mode (--send) is unaffected by design per INV-018 — non-
interactive, no tabs concept; CLI keeps inline tool-event rendering.

Contract: docs/contracts/issues/13.contract.md (drift-check clean,
two amendments applied from Volva contract-paraphrase pass).

Tests: +9 net (TestLayoutShape × 7 + TestTuiPresenterState routing
× 3, minus 1 deprecated test_tool_start_demoted superseded by
test_tool_start_routes_to_tools_log). 236 total GREEN; ruff clean.

Live smoke against personal Worldtree's mimir: tool-using turn
(KB search) populated tools_log with tool_start + tool_result for
search_library + read_note; transcript stayed chat-only with
worker_phase + thinking. Routing-not-duplication confirmed
end-to-end.

persistent-memory.md

@@ -32,17 +32,28 @@ separate dev team rather than an in-tree Worldtree tool.
 
 ## Current state / in-flight
 
-_As of 2026-05-24 (post-v0.3.0 startup agent picker):_
+_As of 2026-05-24 (post-v0.4.0 §5 entry point: layout reshape +
+Tools pane):_
 
-**Status: v0.3.0 shipped.** Eight core issues complete (`sse_client`
+**Status: v0.4.0 shipped.** Nine core issues complete (`sse_client`
 #1, `sessions` #2, `cli` #3, `tui` #4, `--end-user-id` #5, TUI
 startup error visibility #6, presenter contract semantics amendment
-#12, startup agent picker #8) + robustness fix #7 (MalformedSseData
-+ empty-skip) + v0.2.1 TUI layout fix. 227/227 tests GREEN; ruff
-clean.
+#12, startup agent picker #8, §5 layout reshape + Tools pane #13)
++ robustness fix #7 (MalformedSseData + empty-skip) + v0.2.1 TUI
+layout fix. 236/236 tests GREEN; ruff clean.
+
+**§5 v1 entry point shipped (issue #13).** TUI now Horizontal
+two-column: left = chat surface (transcript + thinking-current +
+prompt); right = TabbedContent with single Tools tab (RichLog
+receiving ToolStart/ToolResult events). Routing-not-duplication:
+tool events leave the main transcript entirely. Ctrl+1 activates
+Tools tab without losing Input focus (INV-016). New `pane-name`
+Static in the footer (static "Tools" v1; dynamic when more tabs
+land). CLI mode (--send) unaffected by design — INV-018.
 
 Last commits on `main`:
-- v0.3.0 feat(sessions,cli,tui): issue #8 — startup agent picker
+- v0.4.0 feat(tui): issue #13 — §5 layout reshape + Tools pane
+- `d30be12` feat(sessions,cli,tui): issue #8 — startup agent picker (v0.3.0)
 - `c85f6bd` fix(tui): anchor layout via dock so Input never moves (v0.2.1)
 - `3b9c610` feat(cli,tui): issue #12 — presenter contract semantics amendment (v0.2.0)
 - `8282156` snapshot: persistent-memory Heimdall scope-model foot-gun
@@ -64,10 +75,14 @@ Last commits on `main`:
   "a lot better" interactively.
 
 **Outstanding operator-side todos:**
-- **Interactive TUI picker eyeball** — `source env.sh && uv run
-  ratatoskr --new` (no flags after) should show the picker; pick
-  lofn; type a message; verify response streams cleanly. Auto-pick
-  smoke confirmed the wiring; visual confirmation pending.
+- **Interactive §5 layout eyeball** — `source env.sh && uv run
+  ratatoskr --new --agent mimir`, ask a tool-using question
+  ("search your KB for X"). Confirm: left column shows chat /
+  thinking; right column's Tools tab shows tool_start +
+  tool_result with `· ` prefix; Ctrl+1 doesn't break input focus;
+  no width-clamp issues on the operator's terminal. Programmatic
+  smoke confirmed all the routing + binding; visual confirmation
+  pending.
 - **Post-v0.2.1 TUI multi-turn eyeball** — confirm thinking-run
   bouncing is gone across multiple turns; the layout fix has only
   been confirmed for a single turn so far.