fix: the practice live-view law — live is positive evidence; absorb custom markers

The thinking-submission incident (owner report, 2026-10-05): two spinners
sandwiching the submitted thinking card, and the card doubling once tokens
flowed. Records on disk were clean — both bugs were live-view-only.

- view.ts LIVE IS POSITIVE EVIDENCE (owner ruling): a tool call renders
  live (input-streaming) ONLY when its own message is streaming THIS turn
  (streamingIds) — session busyness can never resurrect a settled call.
  The pose turn's problem call kept flipping to a mid-transcript spinner
  because the fallback keyed on live.inFlight. applyResultTo's placeholder
  fork now also MARKS the settled ack (input-available) instead of leaving
  the guessed state standing. Live cards now sit at the bottom by
  construction, never mid-transcript.
- session-core.ts absorbed(): the custom role gets its identity key
  (customType + details deep-equal) — the optimistic thinking marker is
  dropped when the write-ahead's server copy lands, so the +400ms
  adoption window can no longer double the card. Total over roles; types
  that never appear optimistically never reach the branch.

Pinned: settled problem never live mid-turn; this turn's streaming call
stays shimmer; dangling-settled is input-available; absorbed by
customType+details (different details = different submission); model-level
adoption keeps exactly one marker.

components/session-core.ts

@@ -23,6 +23,7 @@ import {
 	newUserMessage,
 	projectView,
 	type ChatInput,
+	type LhMarkerMessage,
 	type LhMessage,
 	type LhViewMessage,
 	type LiveExecution,
@@ -134,9 +135,30 @@ export function absorbed(m: LhMessage, record: readonly LhMessage[]): boolean {
 				(r as ToolResultMessage).toolCallId === toolCallId,
 		);
 	}
+	if (role === "custom") {
+		// Markers (the thinking submission, 2026-10-05 — the doubled-card
+		// bug: the optimistic practice-thinking card was never absorbed, so
+		// the adoption window rendered it beside the write-ahead's server
+		// copy for the whole turn). TOTAL over roles by identity key — a
+		// marker is itself when its customType AND structured details match;
+		// types that never appear optimistically simply never reach here.
+		const marker = m as LhMarkerMessage;
+		return record.some(
+			(r) =>
+				(r as { role?: string }).role === "custom" &&
+				(r as LhMarkerMessage).customType === marker.customType &&
+				sameDetails((r as LhMarkerMessage).details, marker.details),
+		);
+	}
 	return false;
 }
 
+/** Structural deep-equal for marker details (JSON-stable payloads — the
+ *  constructors mint plain data). */
+function sameDetails(a: unknown, b: unknown): boolean {
+	return JSON.stringify(a) === JSON.stringify(b);
+}
+
 export interface SessionState {
 	messages: LhViewMessage[];
 	nativeMessages: LhMessage[];

src/core/view.ts

@@ -181,13 +181,20 @@ export function projectView(messages: readonly LhMessage[], live?: LiveTurnState
 			const reasoning: LhViewPart[] = [];
 			let textN = 0;
 			let reasoningN = 0;
+			// LIVE IS POSITIVE EVIDENCE (owner, 2026-10-05): a call renders
+			// live ONLY when its own message is streaming THIS turn — session
+			// busyness alone can never resurrect a settled call (the practice
+			// bug: a thinking submission flipped the POSE turn's problem call
+			// back to a spinner mid-transcript; live cards belong at the
+			// bottom, and this gate is what puts them there by construction).
+			const streamingMessage = live?.streamingIds.has(m.id) === true;
 			for (const block of assistant.content) {
 				if (block.type === "text") {
 					rest.push({ type: "text", id: `${m.id}-t${textN++}`, text: block.text, state: "done" });
 				} else if (block.type === "thinking") {
 					reasoning.push({ type: "reasoning", id: `${m.id}-r${reasoningN++}`, text: block.thinking, state: "done" });
 				} else if (block.type === "toolCall") {
-					rest.push(toolPartOf(block, live));
+					rest.push(toolPartOf(block, live, streamingMessage));
 				}
 			}
 			const parts: LhViewPart[] = [...reasoning, ...rest];
@@ -232,10 +239,15 @@ function isPlaceholderResultTool(name: string): boolean {
 	return (QUESTION_TOOLS as readonly string[]).includes(name) || name === "problem";
 }
 
-/** A tool call block → its view part, with the live execution layer. */
+/** A tool call block → its view part, with the live execution layer.
+ * `streamingMessage` — POSITIVE EVIDENCE (owner, 2026-10-05): this call's
+ * own message is streaming THIS turn. The input-streaming shimmer keys on
+ * it, never on session busyness: a call from a settled message can never
+ * render live, whatever else is running. */
 function toolPartOf(
 	block: { id: string; name: string; arguments?: unknown },
 	live: LiveTurnState | undefined,
+	streamingMessage: boolean,
 ): LhViewPart {
 	const part: LhViewPart = {
 		type: `tool-${block.name}`,
@@ -262,10 +274,11 @@ function toolPartOf(
 			part.output = exec.output;
 		}
 	} else {
-		// No execution yet: mid-turn it is input-streaming (the shimmer
-		// activity); in a settled record a dangling call is the dock's
-		// pending question (input-available).
-		part.state = live?.inFlight ? "input-streaming" : "input-available";
+		// No execution yet: live ONLY on positive evidence — the call's own
+		// message is streaming this turn (its arguments may literally be
+		// mid-write). Anything else is a dangling call from a settled
+		// message — the dock's pending state, never a shimmer.
+		part.state = streamingMessage ? "input-streaming" : "input-available";
 	}
 	return part;
 }
@@ -280,7 +293,17 @@ function applyResultTo(part: LhViewPart | undefined, result: ToolResultMessage):
 		// AnsweredCard a null and crash the render (the live crash, 2026-09-26).
 		const tool = part.type.startsWith("tool-") ? part.type.slice("tool-".length) : part.type;
 		const isQuestion = isPlaceholderResultTool(tool);
-		if (isQuestion && !result.isError && result.details == null) return;
+		if (isQuestion && !result.isError && result.details == null) {
+			// The placeholder fork (fork 2) stands: the clean pose/ask ack carries
+			// no card data — NEVER output-available. But the call IS settled
+			// (the practice bug, 2026-10-05: this early-return left the part on
+			// whatever toolPartOf guessed, which mid-turn resurrected a settled
+			// problem as a live spinner). input-available is the settled truth:
+			// the ProblemCard reads the call's input, the dock keys on the
+			// native fold — neither wants the ack's (null) payload.
+			part.state = "input-available";
+			return;
+		}
 		applyResult(part, result);
 	}
 	// A result with no visible part (e.g. a call whose assistant message

tests/session-core.test.ts

@@ -24,7 +24,8 @@ import { afterEach, describe, it } from "node:test";
 import { absorbed, pendingCallTool, SessionModel } from "../components/session-core.ts";
 import type { ChatInput } from "../src/core/input-events.ts";
 import type { LhMessage } from "../src/core/native-messages.ts";
-import { newUserMessage, newAnswerResult, needsContinuation, endsInDismissal } from "../src/core/native-messages.ts";
+import { newUserMessage, newAnswerResult, newThinkingMessage, needsContinuation, endsInDismissal } from "../src/core/native-messages.ts";
+import { projectView } from "../src/core/index.ts";
 import { dismissedAnswer } from "../src/core/question-core.ts";
 import { buildAnswer, type QuestionData } from "../src/core/question-core.ts";
 
@@ -937,3 +938,106 @@ describe("newAnswerResult two audiences", () => {
 		assert.equal((msg.details as { questionText?: string }).questionText, "Which planet is closest to the Sun?");
 	});
 });
+
+// ─── the practice live-view law (owner, 2026-10-05) ─────────────────────────
+//
+// The two-spinners + doubled-card incident: submitting thinking flipped the
+// POSE turn's problem call back to a live spinner mid-transcript (session
+// busyness leaked into per-call state), and the optimistic thinking marker
+// was never absorbed (role "custom" was missing from absorbed()), so the
+// adoption window rendered the submission twice for the whole turn.
+
+/** The post-settle pose-turn record of a practice session. */
+function poseRecord(): LhMessage[] {
+	return [
+		{ id: "m1", role: "user", content: "db practice" },
+		{
+			id: "m3",
+			role: "assistant",
+			content: [{ type: "toolCall", id: "call-p1", name: "problem", arguments: { statement: "Q?" } }],
+		} as unknown as LhMessage,
+		{
+			id: "m4",
+			role: "toolResult",
+			toolCallId: "call-p1",
+			toolName: "problem",
+			content: [{ type: "text", text: "Problem posed — the turn ends here." }],
+			details: null,
+		} as unknown as LhMessage,
+	] as LhMessage[];
+}
+
+describe("the live-view law — live is positive evidence, not session busyness", () => {
+	it("a settled problem call NEVER renders live during another turn (the two-spinner bug)", () => {
+		// The thinking turn's live state: inFlight, but NOTHING streams that
+		// touches the pose call, and the executions map (per-turn) is empty.
+		const live = { executions: new Map(), inFlight: true, streamingIds: new Set<string>() };
+		const view = projectView(poseRecord(), live);
+		const problem = view.flatMap((m) => m.parts).find((p) => p.type === "tool-problem");
+		assert.ok(problem, "the problem part projects");
+		assert.equal(problem!.state, "input-available", "settled = the ProblemCard, never a shimmer");
+	});
+
+	it("a call in THIS turn's streaming message stays input-streaming (the shimmer's true home)", () => {
+		const live = { executions: new Map(), inFlight: true, streamingIds: new Set(["c_as1"]) };
+		const messages = [
+			...poseRecord(),
+			{
+				id: "c_as1",
+				role: "assistant",
+				content: [{ type: "toolCall", id: "call-c1", name: "conclude", arguments: { outcome: "solved" } }],
+			} as unknown as LhMessage,
+		];
+		const view = projectView(messages, live);
+		const conclude = view.flatMap((m) => m.parts).find((p) => p.type === "tool-conclude");
+		assert.ok(conclude, "the conclude part projects");
+		assert.equal(conclude!.state, "input-streaming", "the live card renders at the bottom, by construction");
+	});
+
+	it("a DANGLING call in a settled message is the dock's pending — not a mid-turn shimmer", () => {
+		const live = { executions: new Map(), inFlight: true, streamingIds: new Set<string>() };
+		const messages = [
+			{ id: "m1", role: "user", content: "go" },
+			{
+				id: "m2",
+				role: "assistant",
+				content: [{ type: "toolCall", id: "call-p9", name: "problem", arguments: { statement: "Q?" } }],
+			} as unknown as LhMessage,
+		] as LhMessage[];
+		const view = projectView(messages, live);
+		const part = view.flatMap((m) => m.parts).find((p) => p.type === "tool-problem");
+		assert.equal(part!.state, "input-available", "no evidence, no shimmer — even mid-turn");
+	});
+});
+
+describe("absorbed — the custom role (the doubled thinking card)", () => {
+	it("absorbs the optimistic thinking marker by customType + details", () => {
+		const optimistic = { ...newThinkingMessage("call-p1", false, "my trace"), id: "c_opt1" } as LhMessage;
+		const serverCopy = { ...newThinkingMessage("call-p1", false, "my trace"), id: "srv_1" } as LhMessage;
+		assert.ok(absorbed(optimistic, [...poseRecord(), serverCopy]), "same submission → the local copy drops");
+		// A DIFFERENT submission (commit flag, text) is its own marker.
+		const other = { ...newThinkingMessage("call-p1", true, "my trace"), id: "srv_2" } as LhMessage;
+		assert.ok(!absorbed(optimistic, [...poseRecord(), other]), "different details → not the same submission");
+		// The c_ gate: server stamps are never absorbed, whatever the role.
+		assert.ok(!absorbed(serverCopy, [optimistic]), "server ids never drop");
+	});
+
+	it("the adoption window cannot double the card (model-level end-to-end)", () => {
+		// The exact client sequence of the incident: the optimistic marker in
+		// the tail (client id), then the +400ms adoption fetch swaps in the
+		// write-ahead record (server id). ONE card must remain.
+		const m = model({ chatId: "chat_x", initialMessages: poseRecord() });
+		const optimistic = { ...newThinkingMessage("call-p1", false, "my trace"), id: "c_opt1" } as LhMessage;
+		m.applyWireEvent({ type: "message_start", message: optimistic });
+		assert.equal(
+			m.getState().nativeMessages.filter((x) => (x as { role?: string }).role === "custom").length,
+			1,
+			"the optimistic marker is in the tail",
+		);
+		const serverCopy = { ...newThinkingMessage("call-p1", false, "my trace"), id: "srv_1" } as LhMessage;
+		m.adoptRecord([...poseRecord(), serverCopy]);
+		const customs = m.getState().nativeMessages.filter((x) => (x as { role?: string }).role === "custom");
+		assert.equal(customs.length, 1, "the server copy replaced the optimistic one — no doubling");
+		assert.equal((customs[0] as { id?: string }).id, "srv_1");
+	});
+});