feat(sources v1): the agent locates files itself — ls/find/grep + tool-call cards

User pivot (2026-09-19): no attachments UI at all. Pasting paths is native
for technical users and alien for everyone else - so the agent gets the
tools to find what the learner merely NAMES. The learner communicates in
messages; the agent locates and reads. Zero cross-stream seams: paths
already live in tool parts, so the sources "list" is the transcript.

- ls/find/grep: pi-verbatim schemas, descriptions, and output formats
  (fd's glob semantics, rg's path:line: match format, pi's truncation
  notices), ported to pure Node - no binaries, no shell-out, read-only by
  construction. Deltas from pi: home-anchored resolution (the harness has
  no cwd), .gitignore replaced by hard noise exclusions
  (node_modules/.git/Library/.Trash), 10s walk timeout with partial results.
- read: description swapped to pi-verbatim (doctrine moved to the prompt);
  relative paths now resolve against the learner's home like the rest.
- prompts/shared/05-learner-files.md: one minimal doctrine fragment
  composed into BOTH agents (composeInstructions grew a shared/ dir,
  before the agent's own fragments). teacher/30-jobs.md keeps only the
  pdf-dispatch addendum.
- ToolCallCard: the generic quiet tool-call card the user specced -
  collapsed one-liner (tool name + headline argument), expandable to full
  input/output, errors red, image payloads never render. Registered for
  read/ls/find/grep.
- ui-message.ts: TeacherUITools entries for the four tools (mechanical).
- tests: fs-tools suite (glob semantics, pi formats, exclusions, limits),
  registry/card renders, shared-fragment composition pins, tool-registry
  key updates, read re-anchor.

components/artifacts/index.ts

@@ -4,6 +4,7 @@ import { DemoCard } from "@/components/artifacts/demo-card";
 import { JobCard, PdfJobCard } from "@/components/artifacts/job-card";
 import { VisualCard } from "@/components/artifacts/visual-card";
 import { ProbeDoneCard } from "@/components/artifacts/probe-done-card";
+import { ToolCallCard } from "@/components/artifacts/tool-call-card";
 
 /**
  * Artifact renderer registry — the extension point for tool-part UI.
@@ -29,4 +30,11 @@ export const artifactRenderers: Record<string, ComponentType<ArtifactPartProps>>
 	// The probe conclusion: the assessment belongs to the learner as much as
 	// to the transcript (docs/probe-teach-split.md §2). Plain v1 card.
 	probe_done: ProbeDoneCard,
+	// The learner-filesystem set (sources v1): one quiet expandable
+	// tool-call card each — collapsed one-liner (tool name + headline
+	// argument), full input/output on expand.
+	read: ToolCallCard,
+	ls: ToolCallCard,
+	find: ToolCallCard,
+	grep: ToolCallCard,
 };