feat: model + thinking control — the stats bar's picker, on pi-ai's catalog

The model-control wave (user-decided design, 2026-09-12): ONE controller
for the conversation agents (prober/teacher are functionally one agent);
background sub-agents stay config-pinned. pi-ai owns the registry — the
shipped 366-model OpenRouter catalog (cost, context, modality,
thinkingLevelMap), getSupportedThinkingLevels/clampThinkingLevel for the
per-model thinking truth, and streamSimple's automatic clamp. No second
registry to drift out of sync.

Seams:
- config.ts: ReasoningEffort retired for pi's ThinkingLevel
  (off|minimal|low|medium|high|xhigh|max). GLM roles go honest at "low" —
  pi's catalog says GLM-5.3-flash accepts exactly low|high|max, and the old
  "minimal" was silently clamped to low by streamSimple since the swap;
  nothing changes behaviorally. visualMaker → qwen/qwen3.8-flash (fixes
  the dead qwen/qwen3.8-max slug — the catalog only ships -0902; also the
  user's cost pick, 0.15/0.47 per-1M).
- src/agent/models.ts: piEngineFor(role, settings?) — provider+id resolved
  from the catalog, thinking level from settings ?? config, CLAMPED to the
  model's supported list (a settings change between models can never send
  an invalid level). PiEngine gains `level` (observability/tests).
- ChatRecord.settings {model?: {provider, id}, thinkingLevel?} — written
  by PUT /api/chats/[id]/settings (replace-whole, no updatedAt churn),
  read by chat-handler at turn composition: agents are stateless per turn,
  so the change is next-turn-effective by construction. The turns log
  still records the ACTUAL billed model (the honest witness).
- GET /api/models: the configured-provider catalog as client-safe DTOs
  (core/contracts/models.ts) + config defaults; a second provider joins
  the picker by registering it in piModels() — nothing else changes.
- PUT settings validation gate (src/server/model-catalog.ts): unknown
  provider/model or unsupported level → 400 carrying the supported list,
  never a silent clamp.
- scripts/sync-pricing.ts: regenerated PRICES/CONTEXT_LIMITS from pi-ai's
  shipped openrouter.json (offline; same source as the engine + picker).
  All 366 models priced; glm's stale 0.15/0.5 → pi's 0.075/0.25, limit
  1310720 → 1048576 — cost is inferred at read time, so history re-prices.
- UI (components/model-picker.tsx): stats-bar right side becomes model +
  thinking buttons; menus open ABOVE; fuzzy search over "provider id
  name" (core/fuzzy.ts — pi's /model pattern); model rows show name/id/
  price/context; the thinking menu lists exactly the chosen model's
  supported levels (GLM: low|high|max — no dead options, no "off").
  Model switch drops an incompatible pinned level (falls back to config,
  which clamps honestly) rather than carrying a 400.

Tests (350/350, +15): catalog projection + defaults, the settings gate,
pi thinking truth pinned against upgrades (glm low|high|max; minimal→low;
off→low — GLM cannot disable thinking), the engine factory's
override/fallback/clamp/throw matrix, fuzzy ranking, store round-trip,
and the re-priced folds (usage, stats bar, activity dock).

Live smoke (disposable driver, deleted): catalog route 366 + defaults;
glm+minimal → 400 + supported; turn 1 billed qwen/qwen3.8-flash under
the override; mid-session switch flipped turn 2 to glm; clear-overrides
restored the config pin. ALL CHECKS PASS on real OpenRouter.

tests/render-stats-bar.test.tsx

@@ -3,11 +3,11 @@ import { describe, it } from "node:test";
 import assert from "node:assert/strict";
 import { StatsBar } from "../components/stats-bar.tsx";
 import { prettyModel } from "../components/usage-format.ts";
-import type { TurnUsage } from "../src/core/contracts.ts";
+import type { ChatSettings, TurnUsage } from "../src/core/contracts.ts";
 
 // The stats bar: folds only (no cost math in the component), the "—"
-// doctrine for absent data, honest cost (never a fake $0), and the
-// model/thinking placeholder chip for the coming control.
+// doctrine for absent data, honest cost (never a fake $0), and the model +
+// thinking control (components/model-picker.tsx — pi-ai catalog backed).
 
 function step(inputTokens: number, outputTokens: number, over: Record<string, number | undefined> = {}) {
 	return { inputTokens, outputTokens, cacheReadTokens: undefined, cacheWriteTokens: undefined, reasoningTokens: undefined, ...over };
@@ -24,28 +24,40 @@ function turn(over: Partial<TurnUsage> = {}): TurnUsage {
 	};
 }
 
+const SETTINGS_STUB = (_s: ChatSettings) => {};
+
 describe("stats bar", () => {
 	it("renders — everywhere when the record has no turns yet (doctrine)", () => {
-		const html = renderToStaticMarkup(<StatsBar turns={[]} />);
+		const html = renderToStaticMarkup(
+			<StatsBar turns={[]} chatId="chat_x" onSettingsSaved={SETTINGS_STUB} />,
+		);
 		assert.match(html, /data-testid="stats-bar"/);
 		assert.match(html, /data-testid="stats-context">—</);
 		assert.match(html, /data-testid="stats-cost">—</);
-		assert.match(html, /data-testid="stats-model">—</);
+		// no turns, no settings, catalog not loaded → both control labels "—"
+		assert.match(html, /data-testid="stats-model"[^>]*><span>—<\/span>/);
 		assert.match(html, /Thinking —</);
 	});
 
 	it("folds context + cost from the turns log (core/prices, no local math)", () => {
-		const html = renderToStaticMarkup(<StatsBar turns={[turn(), turn()]} />);
-		// last turn's last call: 10k in + 1k out = 11k; limit 1,310,720 → "1.3M"
-		assert.match(html, /data-testid="stats-context">11k \/ 1\.3M</);
-		// each turn: 10k fresh input ×0.15 + 1k output ×0.5 = $0.002 → two = $0.0040
-		assert.match(html, /data-testid="stats-cost">\$0\.0040</);
-		// model chip: pretty name from the last turn's model id
-		assert.match(html, /data-testid="stats-model">Glm 5\.3 Flash</);
+		const html = renderToStaticMarkup(
+			<StatsBar turns={[turn(), turn()]} chatId="chat_x" onSettingsSaved={SETTINGS_STUB} />,
+		);
+		// last turn's last call: 10k in + 1k out = 11k; pi catalog limit
+		// 1_048_576 → "1M" (tables regenerated from pi-ai's catalog)
+		assert.match(html, /data-testid="stats-context">11k \/ 1M</);
+		// pi catalog price 0.075/0.25 per 1M: each turn 10k×0.075 + 1k×0.25
+		// = $0.001 → two = $0.0020
+		assert.match(html, /data-testid="stats-cost">\$0\.0020</);
+		// model button label falls back to the last turn's actual model
+		// (the catalog + settings are what drive it once loaded)
+		assert.match(html, /data-testid="stats-model"[^>]*><span>Glm 5\.3 Flash<\/span>/);
 	});
 
 	it("shows — for cost when every turn is unpriceable, never a fake $0", () => {
-		const html = renderToStaticMarkup(<StatsBar turns={[turn({ model: "nope/unknown" })]} />);
+		const html = renderToStaticMarkup(
+			<StatsBar turns={[turn({ model: "nope/unknown" })]} chatId="chat_x" onSettingsSaved={SETTINGS_STUB} />,
+		);
 		assert.match(html, /data-testid="stats-cost">—</);
 		// unknown model also kills the context limit
 		assert.match(html, /data-testid="stats-context">—</);