feat(T2b): sources v0 — read tool + pdf-reader sub-agent

Learner source files, on the teacher's own terms (nothing auto-injects):

- read tool (src/agent/tools/read.ts): pi-read port — path/offset/limit,
  2000-line/50KB truncation with use-offset continuation notices, image
  files (jpg/png/gif/webp/bmp) returned as native image content parts
  (new LhToolImageResult escape hatch in lh-tool.ts). Always-on in both
  the prober and teacher registries (user-decided 2026-09).
- pdf-reader sub-agent (JobKind 'pdf', toggleable, ack-and-steer): triage
  via pdf_info (pdfjs text layer: per-page text/image/math-density),
  targeted pdf_extract, regex pdf_search (hits count as consultation),
  and pdf_render — pages painted by pdfjs onto a canvas shim in headless
  Chrome (the pdfium viewer doesn't paint headless), screenshot fed back
  image-in-the-loop (visual-maker idiom, providerSafePng applied). The
  unread-finish gate bounces a zero-consultation brief once. Teacher gets
  a text brief with page citations only; renders never leave the loop.
- MODELS.pdfReader = qwen/qwen3.8-flash (user override 2026-09-19: the
  look-at-renders workload wants the vision-proven model; catalog listed
  glm-5.3-flash as image-capable but qwen is the known-good daily driver).
- UI: PdfCompleteBadge + PdfBriefCard (steer-card, job-card), dispatch
  card + activity-dock kind entries (type-forced, flagged for UI review).
- Prompts: 'Learner source files' section in teacher/30-jobs.md; read
  line in prober/10-probe-doctrine.md. Doctrine rides tool descriptions
  per the self-contained-tools principle.

tests/demos.test.tsx

@@ -42,7 +42,7 @@ import { SubagentSteerCard } from "../components/artifacts/steer-card.tsx";
 import { DispatchCard } from "../components/artifacts/dispatch-card.tsx";
 import { JobCard } from "../components/artifacts/job-card.tsx";
 import { JobsContext } from "../components/jobs-context.ts";
-import { demoInputSchema, jobTools, visualInputSchema } from "../src/agent/tools/jobs.ts";
+import { demoInputSchema, jobTools, pdfInputSchema, visualInputSchema } from "../src/agent/tools/jobs.ts";
 import { runDemoBuilder } from "../src/agent/subagents/demo-builder.ts";
 import { headlessOverride, type DemoRunResult, type HeadlessApi } from "../src/agent/subagents/headless.ts";
 import { createJobRunner, demoModelOverride, visualModelOverride } from "../src/agent/subagents/runner.ts";
@@ -174,6 +174,9 @@ function noChromeHeadless(): HeadlessApi {
 		renderSvg: async () => {
 			throw new Error("should not render");
 		},
+		renderPdfPages: async () => {
+			throw new Error("should not render");
+		},
 	};
 }
 
@@ -369,6 +372,39 @@ describe("steer card rendering (the delivered artifact)", () => {
 		assert.ok(html.includes("britannica.com/plato"), "source links ride inside the details");
 	});
 
+	it("renders a quiet PDF-reading-complete one-liner (sources v0) whose collapsed details carries the brief + pages", () => {
+		const steer = buildSubagentSteer(
+			{ id: "jpf", kind: "pdf", toolCallId: "cpf" },
+			{
+				path: "/Users/x/course/chapter-3.pdf",
+				question: "What is the integral of x dx?",
+				brief: "The power rule appears on **page 1**: the integral of x dx is x^2/2 + C.",
+				pagesConsulted: [1, 2],
+			},
+		);
+		const html = renderToStaticMarkup(<SubagentSteerCard message={steer as never} />);
+		assert.match(html, /PDF/);
+		assert.match(html, /reading complete/);
+		assert.match(html, /2 pages consulted/);
+		assert.match(html, /<details[^>]*data-testid="pdf-complete-badge"/, "a real disclosure like the research badge");
+		assert.ok(!/<details[^>]*open/.test(html), "collapsed by default");
+		assert.ok(html.includes("power rule"), "the brief rides inside the details");
+		// the path/question are sub-agent context — never learner-facing chrome
+		assert.ok(!html.includes("/Users/x/course/chapter-3.pdf"), "the file path never renders");
+	});
+
+	it("renders the PDF failure brief with the failed badge when the reader FAILED", () => {
+		const steer = buildSubagentSteer(
+			{ id: "jpf2", kind: "pdf", toolCallId: "cpf2" },
+			{ path: "/tmp/doc.pdf", question: "q", brief: "PDF failed: the file could not be opened", pagesConsulted: [] },
+		);
+		const html = renderToStaticMarkup(<SubagentSteerCard message={steer as never} />);
+		assert.match(html, /pdf-brief-card/);
+		assert.match(html, /failed/);
+		assert.match(html, /could not be opened/);
+		assert.ok(!html.includes("pdf-complete-badge"), "no complete badge for a failure");
+	});
+
 	it("renders the visual failure note with no svg when the build FAILED", () => {
 		const steer = buildSubagentSteer({ id: "jv", kind: "visual", toolCallId: "cv" }, { svg: "", notes: "FAILED: iteration limit" });
 		const html = renderToStaticMarkup(<SubagentSteerCard message={steer as never} />);
@@ -750,14 +786,17 @@ describe("tool + renderer registry wiring", () => {
 	it("demo and visual are SERVER-EXECUTED dispatch tools with the contract schemas", () => {
 		const { runner } = testRunner();
 		const tools = jobTools({ chatId: "chat_registry", jobStore, spawn: (job) => void runner.runJob(job.id) });
-		assert.deepEqual(Object.keys(tools).sort(), ["demo", "research", "visual"]);
-		for (const name of ["demo", "visual", "research"] as const) {
+		assert.deepEqual(Object.keys(tools).sort(), ["demo", "pdf", "research", "visual"]);
+		for (const name of ["demo", "visual", "research", "pdf"] as const) {
 			assert.equal(typeof (tools[name] as { execute?: unknown }).execute, "function", `${name} executes server-side — fire-and-forget ack per THE ASYNC PROTOCOL`);
 		}
 		assert.equal(demoInputSchema.safeParse({ title: "T", brief: "b" }).success, true);
 		assert.equal(demoInputSchema.safeParse({ brief: "b" }).success, false, "demo requires a title");
 		assert.equal(visualInputSchema.safeParse({ brief: "b" }).success, true);
 		assert.equal(visualInputSchema.safeParse({}).success, false, "visual requires a brief");
+		assert.equal(pdfInputSchema.safeParse({ path: "/tmp/doc.pdf", question: "q" }).success, true);
+		assert.equal(pdfInputSchema.safeParse({ question: "q" }).success, false, "pdf requires a path");
+		assert.equal(pdfInputSchema.safeParse({ path: "/tmp/doc.pdf" }).success, false, "pdf requires a question");
 	});
 
 	it("the artifact renderer registry maps demo/visual to the W6 cards", () => {