gosalyn: C2-01 packages/library, mapping, scope, commit reader with R1-R7, link resolver, renderItems, library survey (row 212, #416 )

2026-10-20 16:29:31 -05:00
20 changed files with 1329 additions and 2 deletions
@@ -34,7 +34,7 @@ export function setup(t, realPin=false){
 test('shared copy: npm ci, pushed reachability, readonly/existing copy, webui delegation',t=>{
 const s=setup(t),r=s.run('stack-copy.sh',['copy',s.id,'--copies',s.copies]);assert.equal(r.status,0,r.stderr);
 const copy=join(s.copies,s.id);assert.equal(statSync(copy).mode&0o777,0o555);
- for(const f of ['scripts/mosaic','adapters/pi/adapter.sh','packages/queue/src/cli.mjs','package.json','package-lock.json','packages/tasks/requirements.json','packages/project/src/index.mjs','packages/project/schemas/project.schema.json','packages/project/templates/north-star.md','packages/plugins/src/kinds.mjs','packages/plugins/src/loader.mjs'])assert.ok(existsSync(join(copy,f)),f);
+ for(const f of ['scripts/mosaic','adapters/pi/adapter.sh','packages/queue/src/cli.mjs','package.json','package-lock.json','packages/tasks/requirements.json','packages/project/src/index.mjs','packages/library/src/index.mjs','packages/project/schemas/project.schema.json','packages/project/templates/north-star.md','packages/plugins/src/kinds.mjs','packages/plugins/src/loader.mjs'])assert.ok(existsSync(join(copy,f)),f);
 const npm=join(s.bin,'npm');writeFileSync(npm,'#!/bin/sh\nexit 99\n');chmodSync(npm,0o755);
 const existing=s.run('webui-service.sh',['copy',s.id,'--copies',s.copies]);assert.equal(existing.status,0);assert.equal(existing.stdout,`exists: ${copy}\n`);unlinkSync(npm);
 git(s.repo,'update-ref','refs/remotes/origin/refactor',git(s.repo,'hash-object','-w','package.json'));
@@ -0,0 +1,128 @@
+# packages/library
+
+Reads a writing repo by a mapping of folders to books, types, canon and playground. This is Case 2
+row C2-01 (`docs/plans/2026-10-20_case2-rows.md`), built from design sections 1.1 to 1.3 and 7.4 in
+`agents/gosalyn/work/case2/DESIGN.md` on `gosalyn/case2-design`.
+It is pure code with no state. Business file loading (C2-04), sync (C2-03a), the index (C2-05a) and the
+guard (C2-06) build on it.
+
+## Mapping
+
+`checkMapping(entry, where, { fail })` checks a `kind: "library"` project entry and returns a
+deep-frozen copy. `where` names the entry in messages. `fail(code, message)` defaults to throwing a
+`LibraryError`. C2-04 passes its own so a business file refusal carries the file name.
+
+```json
+{
+  "kind": "library",
+  "remote": "https://git.example.invalid/her/books.git",
+  "branch": "main",
+  "vaultPrefix": "books",
+  "types": { "Characters": "character", "Places": "place", "Research": "research" },
+  "manuscript": ["Chapters"],
+  "universes": {
+    "harbor": { "name": "Harbor", "books": ["Book One"], "playground": ["Book One/Playground/"] }
+  }
+}
+```
+
+- `remote` is https with no credentials, query or fragment. `branch` is a plain ref name.
+- `vaultPrefix` is optional, one folder name.
+- `types` maps a folder name to `character`, `place`, `research`, `tracker` or `summary`.
+  `manuscript` lists folder names and shares none with `types`.
+- A universe has `name`, `books` and `playground`. A hybrid adds `kind: "hybrid"`, two or more
+  non-hybrid `sources`, `constraints` (each one `{ "exclude": ... }` or
+  `{ "pin": { "entity", "field", "value" } }`) and `notes`.
+
+Refusals:
+
+| Code | When |
+|---|---|
+| `library-playground-outside-book` | a playground prefix is not strictly inside a book of its own universe |
+| `library-mapping-invalid` | any other shape fault: unknown key, bad remote or branch, a book folder in two universes, a book folder that holds another, a playground prefix that holds another, an unknown hybrid source |
+
+## Scope
+
+`classify(mapping, path)` decides scope from the path alone. Only paths ending in lowercase `.md` are
+mapped. A path under a playground prefix is `playground`. Any other path under a book folder is
+`canon`. Everything else is `unmapped`. The type is the first folder after the book, or after the
+playground prefix: a `types` name, `manuscript`, or `null`.
+
+## Reader
+
+`readLibrary({ repo, commit, mapping })` reads one commit, never a working tree. `repo` may be a
+clone or a bare mirror. `commit` must be a full 40-hex id that names a commit, else `library-commit`.
+Git runs through `git()` and `gitBytes()` from `packages/project/src/git.mjs`, so the same safe config,
+environment and ceiling directory apply. A failed git call refuses `library-git`.
+
+It returns `{ commit, files, problems }`, deep-frozen and sorted. Each file has its path, scope,
+universe, book, type, numbered lines, `bodyLine`, parsed `frontmatter` or `null`, `frontmatterRaw`
+and `links`. Front matter `appears_in` and `relationships` wikilinks count as links.
+
+Problems carry `{ code, path, line, message }`:
+
+| Rule | Meaning | File indexed |
+|---|---|---|
+| R1 | not a regular `100644` blob of at most 1 MiB, or not UTF-8, or holds a NUL | no |
+| R2 | path is unmapped | no |
+| R3 | front matter not fully parsed, `line` is where parsing stopped | yes, front matter kept raw |
+| R4 | link resolves to no file or to more than one | yes, link dropped |
+| R5 | canon file links into the playground | yes |
+| R6 | canon file links into another universe, a hybrid's sources excepted | yes |
+| R7 | two paths differ only in case | no, neither |
+
+The front matter parser takes scalars, quoted strings, flow lists, block lists and wikilinks. Nested
+maps, anchors, block scalars and duplicate keys stop it with R3.
+
+## Links
+
+`resolver(paths, { vaultPrefix })` tries four steps in order, each with the target as written and
+then with `.md` added:
+
+1. `root`: the path from the repo root.
+2. `vault-prefix`: the same path with `vaultPrefix/` stripped.
+3. `relative`: relative to the linking file, never above the repo root.
+4. `shortest`: a target with no `/` that matches the base name of exactly one indexed file.
+
+It resolves only against indexed files. A link to a `.canvas` file or an attachment is R4. A link into
+another repo resolves to nothing. `extractLinks` skips fenced and inline code.
+
+## renderItems
+
+`renderItems(body, { scopeOf, changed })` turns a reply body into the plain text both channels show.
+It is pure. Item kinds are `fact`, `finding`, `correction` (with `from` and `to`), `question` and
+`idea`. Each cite is a path with commit, line range and quote, or a url with a quote.
+
+```
+1. Correction: Chapter 1 says grey.
+   From: "green eyes"
+   To: "grey eyes"
+   [canon] Book One/Characters/Mara Vell.md:9 @bbbbbbb "green eyes" (changed since)
+```
+
+A body of `{ "items": [], "notice": ... }` gives `No cited answer`, `No answer` or `The turn failed`.
+Any other shape gives the fixed line `This reply could not be shown.` and none of the body's text.
+
+## Survey
+
+```sh
+mosaic library survey <repo> [--mapping <file>]
+```
+
+It reads the repo's HEAD commit and prints folder names, file counts by extension, front matter key
+sets and link-form counts. It never prints file text, front matter values, file names or link targets.
+A key that is not a short identifier prints as `(other key)`, since it could be her words. With
+`--mapping` it adds scope counts, resolver step counts and problem counts by rule.
+
+Exit codes follow `packages/project`: 0 done, 2 the repo can't be read (`library-git`,
+`library-commit`), 3 a bad mapping, 4 usage. `scripts/mosaic` sends `library survey` here. Other
+library verbs will be bus verbs.
+
+## Tests
+
+```sh
+node --test packages/library/tests/
+```
+
+Fixtures are made-up repos built per test in a temp dir. A marker string stands in for her text, and
+the survey tests check that it never appears in output.
@@ -0,0 +1,11 @@
+{
+  "name": "@mosaic/library",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "license": "UNLICENSED",
+  "exports": "./src/index.mjs",
+  "scripts": {
+    "test": "node --test tests/*.test.mjs"
+  }
+}
@@ -0,0 +1,8 @@
+// packages/library: her writing repo read by a mapping (Case 2, design 1 and 7.4). See README.md.
+export { LibraryError, RULES, problem, sortProblems } from './problems.mjs';
+export { checkMapping, TYPES } from './mapping.mjs';
+export { classify } from './scope.mjs';
+export { extractLinks, parseWikilink, resolver, formOf } from './links.mjs';
+export { readLibrary, listTree, readTexts, parseFile, parseFrontMatter, headCommit, MAX_BLOB, LINK_FIELDS } from './reader.mjs';
+export { renderItems, KINDS, NOTICES, UNREADABLE } from './render.mjs';
+export { survey, formatSurvey, surveyMain } from './survey.mjs';
@@ -0,0 +1,79 @@
+// Wikilinks and the link resolver of design 1.3. Links are [[target]], [[target|label]] and
+// [[target#heading]], with ![[...]] embeds read the same way. Links inside fenced code blocks and
+// inline code spans are not links, as in Obsidian.
+import { posix } from 'node:path';
+
+const WIKILINK = /(!?)\[\[([^\[\]\n]+?)\]\]/g;
+const MARKDOWN_LINK = /(?<!!)\[[^\[\]\n]*\]\(([^()\s]+)\)/g;
+const FENCE = /^\s{0,3}(`{3,}|~{3,})/;
+
+// One wikilink's parts, or null for text that isn't one.
+export function parseWikilink(text) {
+  const match = /^(!?)\[\[([^\[\]\n]+?)\]\]$/.exec(text);
+  return match ? parts(match[2], match[1] === '!') : null;
+}
+function parts(inner, embed) {
+  const bar = inner.indexOf('|');
+  const target = bar < 0 ? inner : inner.slice(0, bar);
+  const hash = target.indexOf('#');
+  return {
+    file: (hash < 0 ? target : target.slice(0, hash)).trim(),
+    heading: hash < 0 ? null : target.slice(hash + 1).trim(),
+    label: bar < 0 ? null : inner.slice(bar + 1),
+    embed,
+  };
+}
+// The form a link is counted under in the survey.
+export const formOf = link => link.markdown ? 'markdown' : link.embed ? 'embed' : !link.file ? 'self'
+  : link.label !== null ? 'label' : link.heading !== null ? 'heading' : 'plain';
+
+// Links in body lines. `lines` is [[number, text], ...]. Markdown links are returned only with
+// `markdown: true`, for the survey's counts. The resolver follows wikilinks only.
+export function extractLinks(lines, { markdown = false } = {}) {
+  const found = [];
+  let fence = null;
+  for (const [line, text] of lines) {
+    const open = FENCE.exec(text);
+    if (fence) { if (open && open[1][0] === fence[0] && open[1].length >= fence.length) fence = null; continue; }
+    if (open) { fence = open[1]; continue; }
+    const plain = text.replace(/(`+)[^`]*?\1/g, match => ' '.repeat(match.length));
+    for (const m of plain.matchAll(WIKILINK)) found.push({ ...parts(m[2], m[1] === '!'), line });
+    if (markdown) {
+      for (const m of plain.matchAll(MARKDOWN_LINK)) {
+        if (!/^[a-z][a-z0-9+.-]*:/i.test(m[1]) && !m[1].startsWith('#'))
+          found.push({ file: m[1], heading: null, label: null, embed: false, markdown: true, line });
+      }
+    }
+  }
+  return found;
+}
+
+// A resolver over the indexed paths. resolve(from, file) tries, in order: a path from the repo
+// root, the same path with `vaultPrefix/` stripped, a path relative to the linking file, and
+// Obsidian's shortest-path form, a base name that matches exactly one indexed file. Each step tries
+// the target as written and then with `.md` added. A target in another of her repos is not in the
+// index, so it resolves to nothing.
+export function resolver(paths, { vaultPrefix } = {}) {
+  const known = new Set(paths), byBase = new Map();
+  for (const path of known) {
+    const base = posix.basename(path);
+    for (const key of new Set([base, base.replace(/\.md$/, '')])) byBase.set(key, [...(byBase.get(key) ?? []), path]);
+  }
+  const hit = candidate => [candidate, `${candidate}.md`].find(c => known.has(c));
+  return function resolve(from, file) {
+    if (typeof file !== 'string' || !file) return { path: null, step: 'missing' };
+    let path = hit(file);
+    if (path) return { path, step: 'root' };
+    if (vaultPrefix && file.startsWith(`${vaultPrefix}/`) && (path = hit(file.slice(vaultPrefix.length + 1))))
+      return { path, step: 'vault-prefix' };
+    const relative = posix.normalize(posix.join(posix.dirname(from), file));
+    if (relative !== '..' && !relative.startsWith('../') && !relative.startsWith('/') && (path = hit(relative)))
+      return { path, step: 'relative' };
+    if (!file.includes('/')) {
+      const matches = byBase.get(file) ?? [];
+      if (matches.length === 1) return { path: matches[0], step: 'shortest' };
+      if (matches.length > 1) return { path: null, step: 'ambiguous', count: matches.length };
+    }
+    return { path: null, step: 'missing' };
+  };
+}
@@ -0,0 +1,132 @@
+// The library project entry of a business file (design 1.1): her folders mapped onto universes,
+// books, type folders, manuscript folders and playground prefixes. A pure validator. Business file
+// loading wires it in C2-04, which passes its own `fail` so the refusal reads as a business file
+// problem. Agents can't write this entry (M9, C2-04).
+import { raise } from './problems.mjs';
+
+export const TYPES = Object.freeze(['character', 'place', 'research', 'tracker', 'summary']);
+const ID = /^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$/;
+const BRANCH = /^[A-Za-z0-9][A-Za-z0-9._/-]{0,127}$/;
+const CONSTRAINT_KEYS = ['exclude', 'pin'];
+
+// A folder segment from her vault: spaces and capitals are fine, separators, control characters
+// and dot names are not.
+function segment(value) {
+  return typeof value === 'string' && value.length > 0 && value.length <= 255 && value !== '.' && value !== '..'
+    && !/[\/\\\u0000-\u001f\u007f]/.test(value) && value.trim() === value;
+}
+function folder(value) {
+  return typeof value === 'string' && value.length <= 1024 && value.split('/').every(segment);
+}
+const holds = (outer, inner) => inner.startsWith(outer.endsWith('/') ? outer : `${outer}/`);
+
+export function checkMapping(entry, where = 'library', { fail = raise } = {}) {
+  const bad = message => fail('library-mapping-invalid', `${where} ${message}`);
+  const object = (value, name) => {
+    if (value === null || typeof value !== 'object' || Array.isArray(value)) bad(`${name} must be an object`);
+  };
+  const only = (value, keys, name) => {
+    for (const key of Object.keys(value)) if (!keys.includes(key)) bad(`${name} has unknown key ${JSON.stringify(key)}`);
+  };
+  const list = (value, name, check, what) => {
+    if (!Array.isArray(value)) bad(`${name} must be a list`);
+    for (const item of value) if (!check(item)) bad(`${name} holds ${JSON.stringify(item)}, which is not ${what}`);
+    if (new Set(value).size !== value.length) bad(`${name} names an entry twice`);
+    return [...value];
+  };
+
+  object(entry, '');
+  only(entry, ['kind', 'remote', 'branch', 'vaultPrefix', 'universes', 'types', 'manuscript'], 'entry');
+  if (entry.kind !== 'library') bad('kind must be "library"');
+  let url;
+  try { url = new URL(entry.remote); } catch { bad('remote must be an https:// URL'); }
+  if (url.protocol !== 'https:' || url.username || url.password || url.search || url.hash || entry.remote.includes('\0'))
+    bad('remote must be an https:// URL with no credentials, query or fragment');
+  if (typeof entry.branch !== 'string' || !BRANCH.test(entry.branch) || entry.branch.includes('..')
+      || entry.branch.includes('//') || entry.branch.endsWith('/') || entry.branch.endsWith('.lock'))
+    bad('branch must be a plain branch name');
+  if (Object.hasOwn(entry, 'vaultPrefix') && !segment(entry.vaultPrefix)) bad('vaultPrefix must be one folder name');
+
+  object(entry.types, 'types');
+  for (const [name, type] of Object.entries(entry.types)) {
+    if (!segment(name)) bad(`types has ${JSON.stringify(name)}, which is not one folder name`);
+    if (!TYPES.includes(type)) bad(`types.${name} must be one of ${TYPES.join(', ')}`);
+  }
+  const manuscript = list(entry.manuscript, 'manuscript', segment, 'one folder name');
+  for (const name of manuscript) if (Object.hasOwn(entry.types, name)) bad(`manuscript folder ${JSON.stringify(name)} is also a type folder`);
+
+  object(entry.universes, 'universes');
+  if (!Object.keys(entry.universes).length) bad('universes must name at least one universe');
+  const universes = {}, bookOwner = new Map(), prefixes = [];
+  for (const [id, universe] of Object.entries(entry.universes)) {
+    const name = `universes.${id}`;
+    if (!ID.test(id)) bad(`universe id ${JSON.stringify(id)} is not a plain id`);
+    object(universe, name);
+    const hybrid = universe.kind === 'hybrid';
+    only(universe, hybrid ? ['kind', 'name', 'sources', 'books', 'playground', 'constraints', 'notes'] : ['name', 'books', 'playground'], name);
+    if (typeof universe.name !== 'string' || !universe.name.trim() || universe.name.length > 128 || /[\u0000-\u001f]/.test(universe.name))
+      bad(`${name}.name must be a short display name`);
+    const books = list(universe.books, `${name}.books`, folder, 'a folder path');
+    if (!hybrid && !books.length) bad(`${name}.books must name at least one book folder`);
+    for (const book of books) {
+      if (bookOwner.has(book)) bad(`book folder ${JSON.stringify(book)} is in two universes`);
+      bookOwner.set(book, id);
+    }
+    const playground = list(universe.playground ?? [], `${name}.playground`,
+      value => typeof value === 'string' && value.endsWith('/') && folder(value.slice(0, -1)), 'a folder path ending in /');
+    for (const prefix of playground) {
+      // Every playground file must have a universe and a book (1.1, B1).
+      if (!books.some(book => holds(book, prefix) && prefix !== `${book}/`))
+        fail('library-playground-outside-book', `${where} ${name}.playground ${JSON.stringify(prefix)} is not inside one of its books`);
+      prefixes.push(prefix);
+    }
+    const out = { name: universe.name, books, playground };
+    if (hybrid) {
+      out.kind = 'hybrid';
+      out.sources = list(universe.sources, `${name}.sources`, value => typeof value === 'string' && ID.test(value), 'a universe id');
+      if (out.sources.length < 2) bad(`${name}.sources must name two or more universes`);
+      if (!Array.isArray(universe.constraints ?? [])) bad(`${name}.constraints must be a list`);
+      out.constraints = (universe.constraints ?? []).map((constraint, i) => {
+        const at = `${name}.constraints[${i}]`;
+        object(constraint, at);
+        only(constraint, CONSTRAINT_KEYS, at);
+        if (Object.keys(constraint).length !== 1) bad(`${at} must hold exactly one of ${CONSTRAINT_KEYS.join(', ')}`);
+        if (Object.hasOwn(constraint, 'exclude')) {
+          if (!folder(constraint.exclude)) bad(`${at}.exclude must be a source path`);
+          return { exclude: constraint.exclude };
+        }
+        object(constraint.pin, `${at}.pin`);
+        only(constraint.pin, ['entity', 'field', 'value'], `${at}.pin`);
+        if (!folder(constraint.pin.entity) || typeof constraint.pin.field !== 'string' || !constraint.pin.field
+            || !['string', 'number', 'boolean'].includes(typeof constraint.pin.value))
+          bad(`${at}.pin needs an entity path, a field name and a scalar value`);
+        return { pin: { ...constraint.pin } };
+      });
+      if (Object.hasOwn(universe, 'notes') && (typeof universe.notes !== 'string' || universe.notes.length > 4000))
+        bad(`${name}.notes must be text of at most 4000 characters`);
+      if (Object.hasOwn(universe, 'notes')) out.notes = universe.notes;
+    }
+    universes[id] = out;
+  }
+  for (const [id, universe] of Object.entries(universes)) {
+    for (const source of universe.sources ?? []) {
+      if (!Object.hasOwn(universes, source) || universes[source].kind === 'hybrid')
+        bad(`universes.${id}.sources names ${JSON.stringify(source)}, which is not a non-hybrid universe`);
+    }
+  }
+  const books = [...bookOwner.keys()];
+  for (const a of books) for (const b of books) if (a !== b && holds(a, b)) bad(`book folder ${JSON.stringify(a)} holds book folder ${JSON.stringify(b)}`);
+  for (const a of prefixes) for (const b of prefixes) if (a !== b && holds(a, b)) bad(`playground ${JSON.stringify(a)} holds playground ${JSON.stringify(b)}`);
+  if (new Set(prefixes).size !== prefixes.length) bad('a playground prefix is listed twice');
+
+  return deepFreeze({
+    kind: 'library', remote: entry.remote, branch: entry.branch,
+    ...(Object.hasOwn(entry, 'vaultPrefix') ? { vaultPrefix: entry.vaultPrefix } : {}),
+    universes, types: { ...entry.types }, manuscript,
+  });
+}
+
+function deepFreeze(value) {
+  if (value && typeof value === 'object') { for (const item of Object.values(value)) deepFreeze(item); Object.freeze(value); }
+  return value;
+}
@@ -0,0 +1,27 @@
+// Errors and the R-rule problems of design 1.3. A problem never holds back a commit: it names a
+// path and, where there is one, a line, and the index leaves the file or link out.
+export class LibraryError extends Error {
+  constructor(code, message) { super(`${code}: ${message}`); this.code = code; }
+}
+export const raise = (code, message) => { throw new LibraryError(code, message); };
+
+export const RULES = Object.freeze({
+  R1: 'not a regular blob up to 1 MiB of UTF-8 text',
+  R2: 'path is unmapped',
+  R3: 'front matter not fully parsed',
+  R4: 'link resolves to no file or to more than one',
+  R5: 'canon file refers into the playground',
+  R6: 'canon file refers into another universe',
+  R7: 'paths differ only in case',
+});
+
+export function problem(code, path, line, message = RULES[code]) {
+  if (!Object.hasOwn(RULES, code)) raise('library-problem-code', `unknown problem code ${code}`);
+  return Object.freeze({ code, path, ...(Number.isSafeInteger(line) ? { line } : {}), message });
+}
+
+// Stable order for status output and tests: path, then line, then code.
+export function sortProblems(list) {
+  return [...list].sort((a, b) => a.path < b.path ? -1 : a.path > b.path ? 1
+    : (a.line ?? 0) - (b.line ?? 0) || (a.code < b.code ? -1 : a.code > b.code ? 1 : 0));
+}
@@ -0,0 +1,219 @@
+// The commit reader of design 1.3. It reads a commit of her repo, never a working tree: it lists the
+// tree with `git ls-tree -r -z` and reads blobs with `cat-file`, through the same bounded git()
+// and gitBytes() as packages/project, so hooks, protocols and the environment are fixed the same
+// way. Nothing in the repo is checked out or run (D7). Each R-rule is a problem, never a refusal
+// of the commit; the affected file or link is left out of the index.
+import { git, gitBytes } from '../../project/src/git.mjs';
+import { classify } from './scope.mjs';
+import { extractLinks, parseWikilink, resolver } from './links.mjs';
+import { LibraryError, problem, raise, sortProblems } from './problems.mjs';
+
+export const MAX_BLOB = 1024 * 1024;
+const MAX_LISTING = 32 * 1024 * 1024;
+const SHA = /^[0-9a-f]{40}$/;
+const ENTRY = /^([0-7]{6}) (blob|tree|commit) ([0-9a-f]{40}) +(-|\d+)\t(.+)$/s;
+export const LINK_FIELDS = Object.freeze(['appears_in', 'relationships']);
+const READERS = 8;
+
+async function local(promise, message) {
+  try { return await promise; } catch (e) { raise('library-git', `${message} (${e.code ?? 'error'})`); }
+}
+
+export async function headCommit(repo) {
+  return local(git(repo, ['rev-parse', '--verify', '--end-of-options', 'HEAD^{commit}']), 'repository has no readable HEAD commit');
+}
+
+// Every entry of the commit's tree: { mode, type, oid, size, path }. Sizes come from `-l`, so no
+// blob is opened to list it.
+export async function listTree(repo, commit) {
+  if (typeof commit !== 'string' || !SHA.test(commit)) raise('library-commit', 'expected a full commit id');
+  const kind = await local(git(repo, ['cat-file', '-t', commit]), 'commit is not in the repository');
+  if (kind !== 'commit') raise('library-commit', 'not a commit');
+  const bytes = await local(gitBytes(repo, ['ls-tree', '-r', '-z', '-l', '--full-tree', commit], MAX_LISTING), 'tree listing refused');
+  let text;
+  try { text = new TextDecoder('utf-8', { fatal: true }).decode(bytes); }
+  catch { raise('library-git', 'tree listing is not UTF-8'); }
+  const entries = text.split('\0');
+  if (entries.pop() !== '') raise('library-git', 'invalid tree listing');
+  return entries.map(entry => {
+    const m = ENTRY.exec(entry);
+    if (!m) raise('library-git', 'invalid tree listing');
+    return { mode: m[1], type: m[2], oid: m[3], size: m[4] === '-' ? null : Number(m[4]), path: m[5] };
+  });
+}
+
+// R1: only a 100644 blob up to 1 MiB of UTF-8 text without NUL is read.
+export const readable = entry => entry.mode === '100644' && entry.type === 'blob'
+  && Number.isSafeInteger(entry.size) && entry.size <= MAX_BLOB;
+
+// Text of each readable entry, by path. An entry whose bytes aren't UTF-8 text is missing from the
+// map, and the caller reports it under R1.
+export async function readTexts(repo, entries) {
+  const texts = new Map(), queue = [...entries];
+  const decoder = new TextDecoder('utf-8', { fatal: true, ignoreBOM: false });
+  const worker = async () => {
+    for (let entry = queue.shift(); entry; entry = queue.shift()) {
+      const bytes = await local(gitBytes(repo, ['cat-file', 'blob', entry.oid], MAX_BLOB), 'blob read refused');
+      let value;
+      try { value = decoder.decode(bytes); } catch { continue; }
+      if (!value.includes('\0')) texts.set(entry.path, value);
+    }
+  };
+  await Promise.all(Array.from({ length: READERS }, worker));
+  return texts;
+}
+
+const QUOTED = /^"(?:[^"\\]|\\.)*"$|^'(?:[^']|'')*'$/;
+const PLAIN_START = /^[^\s\[\]{}&*!|>%@`"'#,]/;
+function scalar(raw) {
+  const value = raw.trim();
+  if (parseWikilink(value)) return { ok: true, value };
+  if (QUOTED.test(value)) {
+    if (value[0] === "'") return { ok: true, value: value.slice(1, -1).replace(/''/g, "'") };
+    try { return { ok: true, value: JSON.parse(value) }; } catch { return { ok: false }; }
+  }
+  if (value === '' || value === '~' || value === 'null') return { ok: true, value: null };
+  if (!PLAIN_START.test(value) || /: |\s#/.test(value) || value.endsWith(':')) return { ok: false };
+  if (value === 'true' || value === 'false') return { ok: true, value: value === 'true' };
+  if (/^-?(0|[1-9]\d*)(\.\d+)?$/.test(value)) return { ok: true, value: Number(value) };
+  return { ok: true, value };
+}
+function flow(raw) {
+  const inner = raw.trim().slice(1, -1), items = [];
+  let current = '', quote = null;
+  for (const ch of inner) {
+    if (quote) { current += ch; if (ch === quote) quote = null; continue; }
+    if (ch === '"' || ch === "'") { quote = ch; current += ch; continue; }
+    if (ch === '[' || ch === ']' || ch === '{' || ch === '}') return { ok: false };
+    if (ch === ',') { items.push(current); current = ''; continue; }
+    current += ch;
+  }
+  if (quote) return { ok: false };
+  if (current.trim() || items.length) items.push(current);
+  const values = [];
+  for (const item of items) { const s = scalar(item); if (!s.ok || !item.trim()) return { ok: false }; values.push(s.value); }
+  return { ok: true, value: values };
+}
+function value(raw) {
+  const text = raw.trim();
+  if (text.startsWith('[') && !parseWikilink(text)) return text.endsWith(']') ? flow(text) : { ok: false };
+  return scalar(text);
+}
+
+// Front matter of design 1.3 (R3): scalars, quoted strings, flow lists and block lists of scalars or
+// wikilinks. Anything else, a nested map, a block scalar or an anchor for example, leaves the whole
+// front matter as raw text with one R3 problem at the line where parsing stopped.
+// Returns { frontmatter, raw, bodyLine, stop } with 1-based line numbers.
+export function parseFrontMatter(lines) {
+  if (lines[0]?.replace(/^/, '').trimEnd() !== '---') return { frontmatter: null, raw: null, bodyLine: 1, stop: null };
+  const close = lines.findIndex((text, i) => i > 0 && /^(---|\.\.\.)\s*$/.test(text));
+  if (close < 0) return { frontmatter: null, raw: null, bodyLine: 1, stop: 1 };
+  const raw = lines.slice(1, close).join('\n'), data = {};
+  let list = null;
+  for (let i = 1; i < close; i++) {
+    const text = lines[i], line = i + 1;
+    if (!text.trim() || /^\s*#/.test(text)) continue;
+    const item = /^(\s*)- (.*)$|^(\s*)-$/.exec(text);
+    if (item && list) {
+      const parsed = scalar(item[2] ?? '');
+      if (!parsed.ok) return { frontmatter: null, raw, bodyLine: close + 2, stop: line };
+      data[list].push(parsed.value);
+      continue;
+    }
+    const pair = /^([^\s:#\-][^:]*?|"[^"]+"|'[^']+')\s*:(?:\s+(.*))?$/.exec(text);
+    if (!pair) return { frontmatter: null, raw, bodyLine: close + 2, stop: line };
+    const key = pair[1].replace(/^(["'])(.*)\1$/, '$2');
+    if (Object.hasOwn(data, key) || key === '__proto__') return { frontmatter: null, raw, bodyLine: close + 2, stop: line };
+    if (pair[2] === undefined || !pair[2].trim()) {
+      const next = lines[i + 1];
+      if (i + 1 < close && /^\s*-( |$)/.test(next)) { data[key] = []; list = key; }
+      else { data[key] = null; list = null; }
+      continue;
+    }
+    list = null;
+    const parsed = value(pair[2]);
+    if (!parsed.ok) return { frontmatter: null, raw, bodyLine: close + 2, stop: line };
+    data[key] = parsed.value;
+  }
+  return { frontmatter: data, raw: null, bodyLine: close + 2, stop: null };
+}
+
+export const splitLines = text => text.replace(/^/, '').split('\n').map(l => l.endsWith('\r') ? l.slice(0, -1) : l);
+
+// One parsed file: its lines (all of them, numbered from 1), front matter and the links it holds.
+// Front matter links come from LINK_FIELDS values that are wikilinks; other values are names.
+export function parseFile(text, { markdown = false } = {}) {
+  const lines = splitLines(text);
+  const fm = parseFrontMatter(lines);
+  const numbered = lines.map((t, i) => [i + 1, t]);
+  const links = extractLinks(numbered.slice(fm.bodyLine - 1), { markdown });
+  if (fm.frontmatter) {
+    for (const field of LINK_FIELDS) {
+      const raw = fm.frontmatter[field];
+      const values = Array.isArray(raw) ? raw : raw === undefined || raw === null ? [] : [raw];
+      for (const v of values) {
+        const link = typeof v === 'string' ? parseWikilink(v.trim()) : null;
+        if (link) links.push({ ...link, field, line: frontMatterLine(lines, fm.bodyLine, field) });
+      }
+    }
+  }
+  return { lines: numbered, bodyLine: fm.bodyLine, frontmatter: fm.frontmatter, frontmatterRaw: fm.raw, stop: fm.stop, links };
+}
+function frontMatterLine(lines, bodyLine, field) {
+  const i = lines.slice(0, bodyLine - 1).findIndex(t => new RegExp(`^["']?${field}["']?\\s*:`).test(t));
+  return i < 0 ? undefined : i + 1;
+}
+
+// Read a commit under a checked mapping (mapping.mjs). Returns the indexed files and every
+// R1-R7 problem: { commit, files: [...], problems: [...] }, frozen, sorted by path.
+export async function readLibrary({ repo, commit, mapping }) {
+  if (!mapping || mapping.kind !== 'library') throw new LibraryError('library-mapping-invalid', 'expected a checked library mapping');
+  const entries = await listTree(repo, commit);
+  const problems = [], twins = new Set(), byLower = new Map();
+  for (const e of entries) byLower.set(e.path.toLowerCase(), [...(byLower.get(e.path.toLowerCase()) ?? []), e.path]);
+  for (const group of byLower.values()) if (group.length > 1) for (const path of group) twins.add(path);
+
+  const candidates = [];
+  for (const entry of entries) {
+    const where = classify(mapping, entry.path);
+    if (where.scope === 'unmapped') { problems.push(problem('R2', entry.path)); continue; }
+    if (twins.has(entry.path)) { problems.push(problem('R7', entry.path)); continue; }
+    if (!readable(entry)) { problems.push(problem('R1', entry.path)); continue; }
+    candidates.push({ entry, where });
+  }
+  const texts = await readTexts(repo, candidates.map(c => c.entry));
+  const files = [];
+  for (const { entry, where } of candidates) {
+    if (!texts.has(entry.path)) { problems.push(problem('R1', entry.path)); continue; }
+    const parsed = parseFile(texts.get(entry.path));
+    if (parsed.stop !== null) problems.push(problem('R3', entry.path, parsed.stop));
+    files.push({ path: entry.path, ...where, name: entry.path.split('/').pop().replace(/\.md$/, ''), ...parsed });
+  }
+
+  const resolve = resolver(files.map(f => f.path), { vaultPrefix: mapping.vaultPrefix });
+  const byPath = new Map(files.map(f => [f.path, f]));
+  for (const file of files) {
+    const kept = [];
+    for (const link of file.links) {
+      if (!link.file) continue;
+      const target = resolve(file.path, link.file);
+      if (!target.path) { problems.push(problem('R4', file.path, link.line)); continue; }
+      const to = byPath.get(target.path);
+      if (file.scope === 'canon') {
+        if (to.scope === 'playground') problems.push(problem('R5', file.path, link.line));
+        const sources = mapping.universes[file.universe].sources ?? [];
+        if (to.universe !== file.universe && !sources.includes(to.universe)) problems.push(problem('R6', file.path, link.line));
+      }
+      kept.push({ ...link, path: target.path, step: target.step });
+    }
+    file.links = kept;
+    delete file.stop;
+  }
+  files.sort((a, b) => a.path < b.path ? -1 : 1);
+  return deepFreeze({ commit, files, problems: sortProblems(problems) });
+}
+
+function deepFreeze(value) {
+  if (value && typeof value === 'object' && !Object.isFrozen(value)) { Object.freeze(value); for (const v of Object.values(value)) deepFreeze(v); }
+  return value;
+}
@@ -0,0 +1,59 @@
+// renderItems(body): how a stored cited reply looks (design 7.4), shared by the Console chat (C2-10b)
+// and the Discord relay (C2-18). Pure: no git, no clock. The caller passes what it knows about cites.
+// The guard (C2-06) checks limits before a reply is stored. This only refuses to show a body that
+// doesn't have the reply shape, and then it shows a fixed line, never the body's text.
+export const KINDS = Object.freeze({ fact: 'Fact', finding: 'Finding', correction: 'Correction', question: 'Question', idea: 'Idea' });
+export const NOTICES = Object.freeze({ 'no-cited-answer': 'No cited answer', 'no-answer': 'No answer', 'turn-failed': 'The turn failed' });
+export const UNREADABLE = 'This reply could not be shown.';
+const SHA = /^[0-9a-f]{40}$/;
+
+const plain = value => value !== null && typeof value === 'object' && !Array.isArray(value);
+const line = n => Number.isSafeInteger(n) && n > 0;
+function cite(value, { scopeOf, changed }) {
+  if (!plain(value) || typeof value.quote !== 'string') return null;
+  if (Object.hasOwn(value, 'url')) {
+    if (typeof value.url !== 'string' || Object.hasOwn(value, 'path')) return null;
+    return { badge: 'web', url: value.url, ref: value.url, quote: value.quote, changed: false };
+  }
+  const { path, commit, lines } = value;
+  if (typeof path !== 'string' || !SHA.test(commit ?? '') || !Array.isArray(lines) || lines.length !== 2
+      || !line(lines[0]) || !line(lines[1]) || lines[1] < lines[0]) return null;
+  const badge = scopeOf?.(path);
+  const ref = `${path}:${lines[0] === lines[1] ? lines[0] : `${lines[0]}-${lines[1]}`} @${commit.slice(0, 7)}`;
+  return { badge: badge === 'canon' || badge === 'playground' ? badge : null, path, commit, lines: [...lines], ref,
+    quote: value.quote, changed: changed?.({ path, commit }) === true };
+}
+const quoted = text => JSON.stringify(text);
+
+// body: the stored message body (a JSON string or the parsed object).
+// options.scopeOf(path) -> 'canon' | 'playground' | undefined, for the scope badge.
+// options.changed({path, commit}) -> true when the file's last commit is newer than the cited one.
+// Returns { kind: 'items', items, text } | { kind: 'notice', notice, text } | { kind: 'unreadable', text }.
+export function renderItems(body, options = {}) {
+  const unreadable = { kind: 'unreadable', text: UNREADABLE };
+  let value = body;
+  if (typeof body === 'string') { try { value = JSON.parse(body); } catch { return unreadable; } }
+  if (!plain(value) || !Array.isArray(value.items)) return unreadable;
+  const keys = Object.keys(value);
+  if (value.items.length === 0) {
+    if (keys.length !== 2 || !Object.hasOwn(NOTICES, value.notice)) return unreadable;
+    return { kind: 'notice', notice: value.notice, text: NOTICES[value.notice] };
+  }
+  if (keys.length !== 1) return unreadable;
+  const items = [];
+  for (const item of value.items) {
+    if (!plain(item) || !Object.hasOwn(KINDS, item.kind) || typeof item.text !== 'string' || !Array.isArray(item.cites)) return unreadable;
+    const correction = item.kind === 'correction';
+    if (correction && (typeof item.from !== 'string' || typeof item.to !== 'string')) return unreadable;
+    const cites = item.cites.map(c => cite(c, options));
+    if (cites.some(c => c === null)) return unreadable;
+    items.push({ kind: item.kind, label: KINDS[item.kind], text: item.text,
+      ...(correction ? { from: item.from, to: item.to } : {}), cites });
+  }
+  const text = items.map((item, i) => [
+    `${i + 1}. ${item.label}: ${item.text}`,
+    ...(item.kind === 'correction' ? [`   From: ${quoted(item.from)}`, `   To: ${quoted(item.to)}`] : []),
+    ...item.cites.map(c => `   ${c.badge ? `[${c.badge}] ` : ''}${c.ref} ${quoted(c.quote)}${c.changed ? ' (changed since)' : ''}`),
+  ].join('\n')).join('\n');
+  return { kind: 'items', items, text };
+}
@@ -0,0 +1,21 @@
+// The scope rule of design 1.2. Scope comes from the path alone (D2): no file content can change it.
+// Paths are repo-relative and compared exactly, case included (R7 handles case-only twins).
+const inside = (folder, path) => path.startsWith(folder.endsWith('/') ? folder : `${folder}/`);
+
+// { scope: 'playground' | 'canon', universe, book, type, folder } or { scope: 'unmapped' }.
+// `type` is the mapped type of the first folder under the book (canon) or under the playground
+// prefix (playground), 'manuscript' for a manuscript folder, else null. `folder` is that folder name.
+export function classify(mapping, path) {
+  if (typeof path !== 'string' || !path.endsWith('.md')) return { scope: 'unmapped' };
+  for (const [universe, entry] of Object.entries(mapping.universes)) {
+    const book = entry.books.find(b => inside(b, path));
+    if (!book) continue;
+    const prefix = entry.playground.find(p => inside(p, path));
+    const rest = path.slice((prefix ?? `${book}/`).length).split('/');
+    const folder = rest.length > 1 ? rest[0] : null;
+    const type = folder === null ? null : Object.hasOwn(mapping.types, folder) ? mapping.types[folder]
+      : mapping.manuscript.includes(folder) ? 'manuscript' : null;
+    return { scope: prefix ? 'playground' : 'canon', universe, book, type, folder };
+  }
+  return { scope: 'unmapped' };
+}
@@ -0,0 +1,126 @@
+// `mosaic library survey <repo> [--mapping <file>]` (design 1.1, 10 step 7). It prints what a mapping
+// needs: folder names, file counts by extension, front matter key sets and link-form counts. It
+// never prints file text, front matter values, file names or link targets. With a mapping it adds
+// scope counts, resolver step counts and R-problem counts by code. It reads the repo's HEAD commit
+// through the commit reader, never the working tree.
+import { readFileSync, realpathSync, statSync } from 'node:fs';
+import { resolve as resolvePath } from 'node:path';
+import { pathToFileURL } from 'node:url';
+import { checkMapping } from './mapping.mjs';
+import { classify } from './scope.mjs';
+import { formOf } from './links.mjs';
+import { headCommit, listTree, parseFile, readable, readLibrary, readTexts } from './reader.mjs';
+import { LibraryError, RULES } from './problems.mjs';
+
+export const USAGE = 'usage: mosaic library survey <repo> [--mapping <file>]';
+// Keys are printed only in the short identifier forms property names take. A key with spaces or of
+// any other shape could be a phrase of hers, so it is counted as one "(other key)".
+const KEY = /^[A-Za-z_][A-Za-z0-9_-]{0,31}$/;
+const OTHER_KEY = '(other key)';
+const FORMS = ['plain', 'label', 'heading', 'embed', 'self', 'markdown'];
+const STEPS = ['root', 'vault-prefix', 'relative', 'shortest'];
+const extension = path => /\.md$/.test(path) ? 'md' : /\.canvas$/.test(path) ? 'canvas' : /\.base$/.test(path) ? 'base' : 'other';
+
+// The survey as data. `mapping` is a checked mapping or undefined.
+export async function survey({ repo, commit, mapping }) {
+  const head = commit ?? await headCommit(repo);
+  const entries = await listTree(repo, head);
+  const folders = new Map();
+  for (const entry of entries) {
+    const slash = entry.path.lastIndexOf('/');
+    const name = slash < 0 ? '' : entry.path.slice(0, slash);
+    const counts = folders.get(name) ?? { md: 0, canvas: 0, base: 0, other: 0 };
+    counts[entry.type === 'blob' ? extension(entry.path) : 'other']++;
+    folders.set(name, counts);
+  }
+  const markdown = entries.filter(e => e.path.endsWith('.md'));
+  const texts = await readTexts(repo, markdown.filter(readable));
+  const keySets = new Map(), forms = Object.fromEntries(FORMS.map(f => [f, 0]));
+  const fields = { appears_in: { wikilink: 0, name: 0 }, relationships: { wikilink: 0, name: 0 } };
+  let noFrontMatter = 0, unparsed = 0;
+  for (const text of texts.values()) {
+    const file = parseFile(text, { markdown: true });
+    if (file.stop !== null) unparsed++;
+    else if (!file.frontmatter) noFrontMatter++;
+    else {
+      const set = [...new Set(Object.keys(file.frontmatter).map(k => KEY.test(k) ? k : OTHER_KEY))].sort().join(', ');
+      keySets.set(set, (keySets.get(set) ?? 0) + 1);
+      for (const field of Object.keys(fields)) {
+        const raw = file.frontmatter[field];
+        for (const v of Array.isArray(raw) ? raw : raw === undefined || raw === null ? [] : [raw])
+          fields[field][typeof v === 'string' && /^\s*!?\[\[[^\]]+\]\]\s*$/.test(v) ? 'wikilink' : 'name']++;
+      }
+    }
+    for (const link of file.links) if (!link.field) forms[formOf(link)]++;
+  }
+  const result = {
+    commit: head, entries: entries.length,
+    folders: [...folders].sort(([a], [b]) => a < b ? -1 : 1).map(([name, counts]) => ({ name, ...counts })),
+    markdown: { files: markdown.length, read: texts.size, noFrontMatter, unparsed },
+    keySets: [...keySets].sort(([a, x], [b, y]) => y - x || (a < b ? -1 : 1)).map(([keys, count]) => ({ keys, count })),
+    forms, fields,
+  };
+  if (mapping) {
+    const scopes = { canon: 0, playground: 0, unmapped: 0 };
+    for (const entry of entries) scopes[classify(mapping, entry.path).scope]++;
+    const library = await readLibrary({ repo, commit: head, mapping });
+    const steps = Object.fromEntries(STEPS.map(s => [s, 0]));
+    for (const file of library.files) for (const link of file.links) steps[link.step]++;
+    const problems = Object.fromEntries(Object.keys(RULES).map(code => [code, 0]));
+    for (const p of library.problems) problems[p.code]++;
+    steps.unresolved = problems.R4;
+    Object.assign(result, { scopes, indexed: library.files.length, steps, problems });
+  }
+  return result;
+}
+
+// Folder names are quoted as JSON strings, so no name can carry a control sequence to the terminal.
+export function formatSurvey(s) {
+  const out = [`commit ${s.commit}`, `entries ${s.entries}`, 'folders (direct children: md canvas base other)'];
+  for (const f of s.folders) out.push(`  ${f.name === '' ? '(root)' : JSON.stringify(f.name)} ${f.md} ${f.canvas} ${f.base} ${f.other}`);
+  out.push(`markdown ${s.markdown.files} files, ${s.markdown.read} read, ${s.markdown.noFrontMatter} without front matter, ${s.markdown.unparsed} with front matter not fully parsed`);
+  out.push('front matter key sets');
+  for (const k of s.keySets) out.push(`  ${k.count} [${k.keys}]`);
+  out.push(`body links ${FORMS.map(f => `${f} ${s.forms[f]}`).join(', ')}`);
+  for (const [field, c] of Object.entries(s.fields)) out.push(`field ${field} wikilink ${c.wikilink}, name ${c.name}`);
+  if (s.scopes) {
+    out.push(`scopes canon ${s.scopes.canon}, playground ${s.scopes.playground}, unmapped ${s.scopes.unmapped}; indexed ${s.indexed}`);
+    out.push(`resolved ${STEPS.map(st => `${st} ${s.steps[st]}`).join(', ')}, unresolved ${s.steps.unresolved}`);
+    out.push(`problems ${Object.entries(s.problems).map(([code, n]) => `${code} ${n}`).join(', ')}`);
+  }
+  return `${out.join('\n')}\n`;
+}
+
+// Exit codes as packages/project's CLI: 0 done, 2 the repo can't be read, 3 a bad mapping, 4 usage.
+export async function surveyMain(argv, io = { stdout: process.stdout, stderr: process.stderr }) {
+  const fail = (code, message) => { io.stderr.write(`library survey: ${message}\n`); return code; };
+  const [verb, ...rest] = argv;
+  if (verb !== 'survey') return fail(4, USAGE);
+  let repo, mappingFile;
+  for (let i = 0; i < rest.length; i++) {
+    if (rest[i] === '--mapping' && i + 1 < rest.length && mappingFile === undefined) mappingFile = rest[++i];
+    else if (!rest[i].startsWith('-') && repo === undefined) repo = rest[i];
+    else return fail(4, USAGE);
+  }
+  if (repo === undefined) return fail(4, USAGE);
+  let mapping;
+  if (mappingFile !== undefined) {
+    let entry;
+    try { entry = JSON.parse(readFileSync(mappingFile, 'utf8')); }
+    catch { return fail(3, `library-mapping-invalid: ${mappingFile} is not a readable JSON file`); }
+    try { mapping = checkMapping(entry, mappingFile); }
+    catch (e) { if (e instanceof LibraryError) return fail(3, e.message); throw e; }
+  }
+  const path = resolvePath(repo);
+  try { if (!statSync(path).isDirectory()) return fail(2, `library-git: ${repo} is not a directory`); }
+  catch { return fail(2, `library-git: ${repo} is not a directory`); }
+  try { io.stdout.write(formatSurvey(await survey({ repo: path, mapping }))); }
+  catch (e) { if (e instanceof LibraryError) return fail(2, e.message); throw e; }
+  return 0;
+}
+
+const entry = () => { try { return import.meta.url === pathToFileURL(realpathSync(process.argv[1])).href; } catch { return false; } };
+if (process.argv[1] && entry()) {
+  const code = await surveyMain(process.argv.slice(2));
+  if (code !== 0) process.exitCode = code;
+}
@@ -0,0 +1,12 @@
+{
+  "kind": "library",
+  "remote": "https://git.example.invalid/writer/books.git",
+  "branch": "main",
+  "vaultPrefix": "books",
+  "universes": {
+    "harbor": {"name": "The Harbor", "books": ["Book One"], "playground": ["Book One/Playground/"]},
+    "second": {"name": "Second World", "books": ["Second World"]}
+  },
+  "types": {"Characters": "character", "Places": "place", "Research": "research", "Tracker": "tracker", "Summaries": "summary"},
+  "manuscript": ["Chapters"]
+}
@@ -0,0 +1,54 @@
+// A repo the test builds in her layout's shape: spaces and capitals in folder names, a .canvas file
+// and an unmapped top-level note. Bodies are made up; MARKER stands in for her text.
+import { mkdtempSync, rmSync, mkdirSync, writeFileSync, readFileSync, symlinkSync, chmodSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { dirname, join } from 'node:path';
+import { execFileSync } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
+import { checkMapping } from '../src/mapping.mjs';
+
+export const MARKER = 'MARKER-7f3a-HER-TEXT';
+export const FIXTURES = fileURLToPath(new URL('./fixtures/', import.meta.url));
+export const mappingEntry = () => JSON.parse(readFileSync(join(FIXTURES, 'mapping.json'), 'utf8'));
+export const mapping = (change = e => e) => checkMapping(change(mappingEntry()));
+
+export const git = (repo, ...args) => execFileSync('git', ['-c', 'user.name=fixture', '-c', '[email protected]',
+  '-c', 'commit.gpgsign=false', '-c', 'core.hooksPath=/dev/null', '-C', repo, ...args], { encoding: 'utf8' }).trim();
+
+export const BASE = {
+  'Book One/Characters/Mara Vell.md': [
+    '---', 'type: character', 'name: Mara Vell', 'appears_in: "[[Book One/Chapters/Chapter 01]]"',
+    'relationships:', '  - "[[Tomas]]"', '  - The Ferryman', '---', `Grey eyes. ${MARKER}`, ''].join('\n'),
+  'Book One/Characters/Tomas.md': ['---', 'type: character', 'name: Tomas', 'appears_in: ["[[Chapter 01]]"]', '---', MARKER, ''].join('\n'),
+  'Book One/Chapters/Chapter 01.md': [
+    '# One', `${MARKER} [[Mara Vell]] met [[Book One/Places/Harbor Town|the harbor]].`,
+    'See [[../Places/Harbor Town#Docks]] and [[books/Book One/Characters/Tomas]].',
+    '```', '[[Not A Link]]', '```', 'Inline `[[Not Either]]` and [a note](Notes.md).', ''].join('\n'),
+  'Book One/Places/Harbor Town.md': ['---', 'type: place', '---', `Salt. ${MARKER}`, ''].join('\n'),
+  'Book One/Playground/What If.md': ['---', 'name: What If', '---', `${MARKER} [[Mara Vell]]`, ''].join('\n'),
+  'Book One/Board.canvas': '{"nodes":[]}\n',
+  'Book One/Playground/Sketch.canvas': '{"nodes":[]}\n',
+  'Inbox Note.md': `${MARKER}\n`,
+  'Second World/Chapters/01.md': `# Elsewhere ${MARKER}\n`,
+};
+
+// repo({files, extra}) writes files (path -> text, or { link } / { mode, text }), commits, and
+// returns { repo, commit }.
+export function repo(t, files = BASE) {
+  const root = mkdtempSync(join(tmpdir(), 'library-'));
+  t.after(() => rmSync(root, { recursive: true, force: true }));
+  const dir = join(root, 'books');
+  mkdirSync(dir);
+  git(dir, 'init', '-q', '-b', 'main');
+  for (const [path, value] of Object.entries(files)) {
+    const file = join(dir, path);
+    mkdirSync(dirname(file), { recursive: true });
+    if (typeof value === 'object' && value.link) symlinkSync(value.link, file);
+    else if (typeof value === 'object' && value.bytes) writeFileSync(file, value.bytes);
+    else writeFileSync(file, typeof value === 'object' ? value.text : value);
+    if (typeof value === 'object' && value.mode) chmodSync(file, value.mode);
+  }
+  git(dir, 'add', '-A');
+  git(dir, 'commit', '-qm', 'fixture');
+  return { root, repo: dir, commit: git(dir, 'rev-parse', 'HEAD') };
+}
@@ -0,0 +1,50 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { extractLinks, parseWikilink, resolver } from '../src/index.mjs';
+
+const PATHS = ['Book One/Characters/Mara Vell.md', 'Book One/Characters/Tomas.md', 'Book One/Places/Harbor Town.md',
+  'Book One/Chapters/Chapter 01.md', 'Book One/Places/Notes.md', 'Book One/Characters/Notes.md', 'Mara Vell.md'];
+const resolve = resolver(PATHS, { vaultPrefix: 'books' });
+const FROM = 'Book One/Chapters/Chapter 01.md';
+
+test('resolver step 1: a path from the repo root, with or without .md', () => {
+  assert.deepEqual(resolve(FROM, 'Book One/Places/Harbor Town'), { path: 'Book One/Places/Harbor Town.md', step: 'root' });
+  assert.deepEqual(resolve(FROM, 'Book One/Places/Harbor Town.md'), { path: 'Book One/Places/Harbor Town.md', step: 'root' });
+  // Root wins over shortest: Mara Vell.md at the root, not the character page.
+  assert.deepEqual(resolve(FROM, 'Mara Vell'), { path: 'Mara Vell.md', step: 'root' });
+});
+
+test('resolver step 2: the same path with vaultPrefix/ stripped', () => {
+  assert.deepEqual(resolve(FROM, 'books/Book One/Characters/Tomas'), { path: 'Book One/Characters/Tomas.md', step: 'vault-prefix' });
+  assert.deepEqual(resolver(PATHS)(FROM, 'books/Book One/Characters/Tomas'), { path: null, step: 'missing' });
+});
+
+test('resolver step 3: a path relative to the linking file, never above the repo root', () => {
+  assert.deepEqual(resolve(FROM, '../Places/Harbor Town'), { path: 'Book One/Places/Harbor Town.md', step: 'relative' });
+  assert.deepEqual(resolve('Book One/Places/Harbor Town.md', './Notes'), { path: 'Book One/Places/Notes.md', step: 'relative' });
+  assert.deepEqual(resolve(FROM, '../../../Book One/Places/Harbor Town'), { path: null, step: 'missing' });
+});
+
+test('resolver step 4: a base name that matches exactly one indexed file', () => {
+  assert.deepEqual(resolve(FROM, 'Tomas'), { path: 'Book One/Characters/Tomas.md', step: 'shortest' });
+  assert.deepEqual(resolve(FROM, 'Harbor Town.md'), { path: 'Book One/Places/Harbor Town.md', step: 'shortest' });
+  assert.deepEqual(resolve(FROM, 'Notes'), { path: null, step: 'ambiguous', count: 2 });
+  assert.deepEqual(resolve(FROM, 'Nobody'), { path: null, step: 'missing' });
+  // A partial path is not a base name.
+  assert.deepEqual(resolve(FROM, 'Places/Harbor Town'), { path: null, step: 'missing' });
+});
+
+test('a link into another of her repos resolves to nothing', () => {
+  assert.deepEqual(resolve(FROM, 'bean-brain/Journal/Today'), { path: null, step: 'missing' });
+  assert.deepEqual(resolve(FROM, '../bean-brain/Journal/Today'), { path: null, step: 'missing' });
+});
+
+test('wikilink forms, embeds, and links skipped inside code', () => {
+  assert.deepEqual(parseWikilink('[[A/B#Head|Label]]'), { file: 'A/B', heading: 'Head', label: 'Label', embed: false });
+  assert.deepEqual(parseWikilink('![[pic.png]]'), { file: 'pic.png', heading: null, label: null, embed: true });
+  assert.equal(parseWikilink('[[a]] and more'), null);
+  const lines = [[1, '[[One]] [[Two|2]] [[Three#H]] ![[Four]] [[#Self]]'], [2, '```js'], [3, '[[Fenced]]'], [4, '```'],
+    [5, 'Inline `[[Code]]` and [md](Five.md) and [web](https://example.invalid/x)']];
+  assert.deepEqual(extractLinks(lines).map(l => [l.file, l.line]), [['One', 1], ['Two', 1], ['Three', 1], ['Four', 1], ['', 1]]);
+  assert.deepEqual(extractLinks(lines, { markdown: true }).filter(l => l.markdown).map(l => l.file), ['Five.md']);
+});
@@ -0,0 +1,82 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { checkMapping, classify, LibraryError } from '../src/index.mjs';
+import { mapping, mappingEntry } from './helpers.mjs';
+
+const refuses = (change, code, pattern) => assert.throws(() => checkMapping(change(mappingEntry())),
+  e => e instanceof LibraryError && e.code === code && (!pattern || pattern.test(e.message)));
+
+test('the fixture mapping checks and comes back frozen', () => {
+  const m = mapping();
+  assert.equal(m.universes.harbor.playground[0], 'Book One/Playground/');
+  assert.ok(Object.isFrozen(m.universes.harbor.books));
+  assert.throws(() => { m.types.Extra = 'place'; });
+});
+
+test('a playground prefix outside its universe books refuses library-playground-outside-book', () => {
+  refuses(e => { e.universes.harbor.playground = ['Second World/Playground/']; return e; }, 'library-playground-outside-book');
+  refuses(e => { e.universes.harbor.playground = ['Elsewhere/']; return e; }, 'library-playground-outside-book');
+  // The whole book as its playground would leave no canon: not inside the book.
+  refuses(e => { e.universes.harbor.playground = ['Book One/']; return e; }, 'library-playground-outside-book');
+});
+
+test('no playground prefix holds another, and no book folder holds another', () => {
+  refuses(e => { e.universes.harbor.playground = ['Book One/Playground/', 'Book One/Playground/Deep/']; return e; },
+    'library-mapping-invalid', /holds playground/);
+  refuses(e => { e.universes.second.books = ['Second World', 'Book One/Part Two']; return e; }, 'library-mapping-invalid', /holds book folder/);
+  refuses(e => { e.universes.second.books = ['Book One']; return e; }, 'library-mapping-invalid', /in two universes/);
+});
+
+test('shape refusals: kind, remote, branch, unknown keys, types, manuscript, folder names', () => {
+  refuses(e => ({ ...e, kind: 'code' }), 'library-mapping-invalid', /kind/);
+  refuses(e => ({ ...e, remote: 'http://git.example.invalid/x.git' }), 'library-mapping-invalid', /https/);
+  refuses(e => ({ ...e, remote: 'https://user:[email protected]/x.git' }), 'library-mapping-invalid', /credentials/);
+  refuses(e => ({ ...e, remote: '[email protected]:x.git' }), 'library-mapping-invalid', /https/);
+  refuses(e => ({ ...e, branch: 'main..x' }), 'library-mapping-invalid', /branch/);
+  refuses(e => ({ ...e, root: '/tmp' }), 'library-mapping-invalid', /unknown key "root"/);
+  refuses(e => { e.universes.harbor.extra = 1; return e; }, 'library-mapping-invalid', /unknown key/);
+  refuses(e => { e.types.Characters = 'villain'; return e; }, 'library-mapping-invalid', /types.Characters/);
+  refuses(e => { e.types['A/B'] = 'place'; return e; }, 'library-mapping-invalid', /one folder name/);
+  refuses(e => ({ ...e, manuscript: ['Characters'] }), 'library-mapping-invalid', /also a type folder/);
+  refuses(e => { e.universes.harbor.books = ['../Book One']; return e; }, 'library-mapping-invalid', /folder path/);
+  refuses(e => ({ ...e, vaultPrefix: 'a/b' }), 'library-mapping-invalid', /vaultPrefix/);
+  refuses(e => ({ ...e, universes: {} }), 'library-mapping-invalid', /at least one universe/);
+  refuses(e => { e.universes['bad id'] = e.universes.second; delete e.universes.second; return e; }, 'library-mapping-invalid', /plain id/);
+});
+
+test('a hybrid universe is a shape the query code can take (1.4), with sources that must exist', () => {
+  const hybrid = e => { e.universes.cross = { kind: 'hybrid', name: 'Crossover', sources: ['harbor', 'second'], books: ['Crossover'],
+    constraints: [{ exclude: 'second/Characters' }, { pin: { entity: 'Book One/Characters/Mara Vell.md', field: 'eyes', value: 'grey' } }],
+    notes: 'Set after book one.' }; return e; };
+  const m = checkMapping(hybrid(mappingEntry()));
+  assert.deepEqual(m.universes.cross.sources, ['harbor', 'second']);
+  refuses(e => { hybrid(e); e.universes.cross.sources = ['harbor', 'nowhere']; return e; }, 'library-mapping-invalid', /non-hybrid universe/);
+  refuses(e => { hybrid(e); e.universes.cross.sources = ['harbor']; return e; }, 'library-mapping-invalid', /two or more/);
+  refuses(e => { hybrid(e); e.universes.cross.constraints = [{ exclude: 'x', pin: {} }]; return e; }, 'library-mapping-invalid', /exactly one/);
+});
+
+test('a caller-supplied fail receives the code, as business file loading will pass it (C2-04)', () => {
+  const seen = [];
+  const fail = (code, message) => { seen.push(code); throw new Error(message); };
+  const entry = mappingEntry();
+  entry.universes.harbor.playground = ['Elsewhere/'];
+  assert.throws(() => checkMapping(entry, 'businesses/acme.json projects.books', { fail }), /businesses\/acme.json projects.books/);
+  assert.deepEqual(seen, ['library-playground-outside-book']);
+});
+
+test('scope comes from the path alone (design 1.2)', () => {
+  const m = mapping();
+  assert.deepEqual(classify(m, 'Book One/Characters/Mara Vell.md'),
+    { scope: 'canon', universe: 'harbor', book: 'Book One', type: 'character', folder: 'Characters' });
+  assert.deepEqual(classify(m, 'Book One/Chapters/Chapter 01.md'),
+    { scope: 'canon', universe: 'harbor', book: 'Book One', type: 'manuscript', folder: 'Chapters' });
+  assert.deepEqual(classify(m, 'Book One/Playground/What If.md'),
+    { scope: 'playground', universe: 'harbor', book: 'Book One', type: null, folder: null });
+  assert.deepEqual(classify(m, 'Book One/Playground/Characters/New.md'),
+    { scope: 'playground', universe: 'harbor', book: 'Book One', type: 'character', folder: 'Characters' });
+  assert.deepEqual(classify(m, 'Book One/Notes.md'), { scope: 'canon', universe: 'harbor', book: 'Book One', type: null, folder: null });
+  assert.equal(classify(m, 'Second World/Chapters/01.md').universe, 'second');
+  for (const path of ['Inbox Note.md', 'Book One/Board.canvas', 'Book One/Playground/Sketch.canvas', 'Book One/Board.base',
+    'Book One/cover.png', 'Book One/Upper.MD', 'Book Onex/a.md', 'book one/a.md', 'Elsewhere/Book One/a.md'])
+    assert.deepEqual(classify(m, path), { scope: 'unmapped' }, path);
+});
@@ -0,0 +1,151 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { writeFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { readLibrary, parseFrontMatter, LibraryError, MAX_BLOB } from '../src/index.mjs';
+import { BASE, git, mapping, repo } from './helpers.mjs';
+
+const codes = (result, path) => result.problems.filter(p => p.path === path).map(p => p.code);
+const file = (result, path) => result.files.find(f => f.path === path);
+
+test('the fixture reads clean: every resolver step, appears_in and relationships wikilinks indexed', async t => {
+  const r = repo(t);
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  assert.equal(result.commit, r.commit);
+  assert.deepEqual(result.files.map(f => [f.path, f.scope]), [
+    ['Book One/Chapters/Chapter 01.md', 'canon'], ['Book One/Characters/Mara Vell.md', 'canon'],
+    ['Book One/Characters/Tomas.md', 'canon'], ['Book One/Places/Harbor Town.md', 'canon'],
+    ['Book One/Playground/What If.md', 'playground'], ['Second World/Chapters/01.md', 'canon']]);
+  const chapter = file(result, 'Book One/Chapters/Chapter 01.md');
+  assert.deepEqual(chapter.links.map(l => [l.path, l.step, l.line]), [
+    ['Book One/Characters/Mara Vell.md', 'shortest', 2], ['Book One/Places/Harbor Town.md', 'root', 2],
+    ['Book One/Places/Harbor Town.md', 'relative', 3], ['Book One/Characters/Tomas.md', 'vault-prefix', 3]]);
+  const mara = file(result, 'Book One/Characters/Mara Vell.md');
+  assert.deepEqual(mara.frontmatter, { type: 'character', name: 'Mara Vell', appears_in: '[[Book One/Chapters/Chapter 01]]',
+    relationships: ['[[Tomas]]', 'The Ferryman'] });
+  assert.deepEqual(mara.links.map(l => [l.field, l.path, l.line]), [
+    ['appears_in', 'Book One/Chapters/Chapter 01.md', 4], ['relationships', 'Book One/Characters/Tomas.md', 5]]);
+  assert.deepEqual(file(result, 'Book One/Characters/Tomas.md').links.map(l => [l.field, l.path]),
+    [['appears_in', 'Book One/Chapters/Chapter 01.md']]);
+  assert.equal(mara.bodyLine, 9);
+  assert.equal(mara.lines[8][0], 9);
+  assert.equal(mara.type, 'character');
+  // Only the unmapped paths are problems: the top-level note and both .canvas files.
+  assert.deepEqual(result.problems.map(p => [p.code, p.path]), [
+    ['R2', 'Book One/Board.canvas'], ['R2', 'Book One/Playground/Sketch.canvas'], ['R2', 'Inbox Note.md']]);
+  assert.ok(Object.isFrozen(result.files[0].links));
+});
+
+test('R1: executables, symlinks, gitlinks, blobs over 1 MiB and non-UTF-8 text are not indexed', async t => {
+  const r = repo(t, { ...BASE,
+    'Book One/Places/Run.md': { text: 'x\n', mode: 0o755 },
+    'Book One/Places/Link.md': { link: 'Harbor Town.md' },
+    'Book One/Places/Big.md': 'x'.repeat(MAX_BLOB + 1),
+    'Book One/Places/Edge.md': 'y'.repeat(MAX_BLOB),
+    'Book One/Places/Latin.md': { bytes: Buffer.from([0x63, 0x61, 0x66, 0xe9, 0x0a]) },
+    'Book One/Places/Nul.md': 'a\0b\n' });
+  git(r.repo, 'update-index', '--add', '--cacheinfo', `160000,${r.commit},Book One/Places/Sub.md`);
+  git(r.repo, 'commit', '-qm', 'gitlink');
+  const result = await readLibrary({ repo: r.repo, commit: git(r.repo, 'rev-parse', 'HEAD'), mapping: mapping() });
+  for (const name of ['Run', 'Link', 'Big', 'Latin', 'Nul', 'Sub']) {
+    assert.deepEqual(codes(result, `Book One/Places/${name}.md`), ['R1'], name);
+    assert.equal(file(result, `Book One/Places/${name}.md`), undefined, name);
+  }
+  assert.ok(file(result, 'Book One/Places/Edge.md'), 'exactly 1 MiB is read');
+});
+
+test('R2: unmapped paths are reported and not indexed', async t => {
+  const r = repo(t);
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  for (const path of ['Inbox Note.md', 'Book One/Board.canvas', 'Book One/Playground/Sketch.canvas']) {
+    assert.deepEqual(codes(result, path), ['R2']);
+    assert.equal(file(result, path), undefined);
+  }
+});
+
+test('R3: front matter not fully parsed stays raw, with the line where parsing stopped', async t => {
+  const r = repo(t, { ...BASE,
+    'Book One/Places/Nested.md': ['---', 'type: place', 'coords:', '  lat: 1', '---', 'Body [[Tomas]]', ''].join('\n'),
+    'Book One/Places/Block.md': ['---', 'summary: |', '  text', '---', ''].join('\n'),
+    'Book One/Places/Open.md': ['---', 'type: place', 'never closed', ''].join('\n') });
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  const nested = file(result, 'Book One/Places/Nested.md');
+  assert.deepEqual(result.problems.filter(p => p.path === 'Book One/Places/Nested.md'), [{ code: 'R3', path: 'Book One/Places/Nested.md', line: 4, message: 'front matter not fully parsed' }]);
+  assert.equal(nested.frontmatter, null);
+  assert.equal(nested.frontmatterRaw, 'type: place\ncoords:\n  lat: 1');
+  assert.deepEqual(nested.links.map(l => l.path), ['Book One/Characters/Tomas.md'], 'still indexed by body');
+  assert.equal(result.problems.find(p => p.path === 'Book One/Places/Block.md').line, 2);
+  assert.equal(result.problems.find(p => p.path === 'Book One/Places/Open.md').line, 1);
+  assert.equal(file(result, 'Book One/Places/Open.md').bodyLine, 1);
+});
+
+test('front matter forms the reader accepts and refuses', () => {
+  const parse = text => parseFrontMatter(text.split('\n'));
+  assert.deepEqual(parse('---\na: plain words\nb: "quoted: yes"\nc: \'it\'\'s\'\nd: [x, "y z", 3]\ne:\n- one\n- "[[Two]]"\nf: [[Wiki]]\ng: true\nh:\n---').frontmatter,
+    { a: 'plain words', b: 'quoted: yes', c: "it's", d: ['x', 'y z', 3], e: ['one', '[[Two]]'], f: '[[Wiki]]', g: true, h: null });
+  for (const bad of ['a: {x: 1}', 'a: &anchor x', 'a: [x, [y]]', 'a: x: y', 'a: 1\na: 2', '  a: 1', 'a: "open', '- loose'])
+    assert.notEqual(parse(`---\n${bad}\n---`).stop, null, bad);
+  assert.deepEqual(parse('no front matter'), { frontmatter: null, raw: null, bodyLine: 1, stop: null });
+});
+
+test('R4: a link to no file, to more than one, or into another repo is reported and not followed', async t => {
+  const r = repo(t, { ...BASE,
+    'Book One/Research/Notes.md': 'a\n', 'Book One/Places/Notes.md': 'b\n',
+    'Book One/Chapters/Links.md': ['[[Nobody]]', '[[Notes]]', '[[bean-brain/Journal/Today]]', '[[Tomas]]', ''].join('\n') });
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  assert.deepEqual(result.problems.filter(p => p.path === 'Book One/Chapters/Links.md').map(p => [p.code, p.line]), [['R4', 1], ['R4', 2], ['R4', 3]]);
+  assert.deepEqual(file(result, 'Book One/Chapters/Links.md').links.map(l => l.path), ['Book One/Characters/Tomas.md']);
+});
+
+test('R5: a canon file that refers into the playground is reported, and the link still goes by path', async t => {
+  const r = repo(t, { ...BASE, 'Book One/Places/Dock.md': 'See [[What If]].\n' });
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  assert.deepEqual(codes(result, 'Book One/Places/Dock.md'), ['R5']);
+  assert.deepEqual(file(result, 'Book One/Places/Dock.md').links.map(l => l.path), ['Book One/Playground/What If.md']);
+  // The playground file links to canon: no problem, R5 is only about canon.
+  assert.deepEqual(codes(result, 'Book One/Playground/What If.md'), []);
+});
+
+test('R6: a canon file that refers into another universe is reported; a hybrid may refer into its sources', async t => {
+  const r = repo(t, { ...BASE, 'Book One/Places/Far.md': 'Like [[Second World/Chapters/01]].\n',
+    'Crossover/Chapters/A.md': 'From [[Mara Vell]] and [[Second World/Chapters/01]].\n' });
+  const hybrid = mapping(e => { e.universes.cross = { kind: 'hybrid', name: 'Cross', sources: ['harbor', 'second'], books: ['Crossover'] }; return e; });
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: hybrid });
+  assert.deepEqual(codes(result, 'Book One/Places/Far.md'), ['R6']);
+  assert.deepEqual(file(result, 'Book One/Places/Far.md').links.map(l => l.path), ['Second World/Chapters/01.md']);
+  assert.deepEqual(codes(result, 'Crossover/Chapters/A.md'), []);
+});
+
+test('R7: two paths that differ only in case are both left out', async t => {
+  const r = repo(t, BASE);
+  writeFileSync(join(r.root, 'twin'), 'twin\n');
+  const blob = git(r.repo, 'hash-object', '-w', join(r.root, 'twin'));
+  git(r.repo, 'update-index', '--add', '--cacheinfo', `100644,${blob},Book One/Characters/tomas.md`);
+  git(r.repo, 'commit', '-qm', 'case twin');
+  const result = await readLibrary({ repo: r.repo, commit: git(r.repo, 'rev-parse', 'HEAD'), mapping: mapping() });
+  for (const path of ['Book One/Characters/Tomas.md', 'Book One/Characters/tomas.md']) {
+    assert.deepEqual(codes(result, path), ['R7'], path);
+    assert.equal(file(result, path), undefined);
+  }
+});
+
+test('the reader reads the commit, never the working tree, and refuses a bad commit id', async t => {
+  const r = repo(t);
+  writeFileSync(join(r.repo, 'Book One/Places/Harbor Town.md'), 'unsaved [[Nobody]]\n');
+  writeFileSync(join(r.repo, 'Book One/Places/Untracked.md'), 'x\n');
+  const result = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  assert.equal(file(result, 'Book One/Places/Harbor Town.md').lines[0][1], '---');
+  assert.equal(file(result, 'Book One/Places/Untracked.md'), undefined);
+  for (const commit of ['HEAD', r.commit.slice(0, 12), '0'.repeat(40), git(r.repo, 'rev-parse', 'HEAD^{tree}')])
+    await assert.rejects(readLibrary({ repo: r.repo, commit, mapping: mapping() }), e => e instanceof LibraryError, commit);
+  await assert.rejects(readLibrary({ repo: r.repo, commit: r.commit, mapping: {} }), /library-mapping-invalid/);
+});
+
+test('a bare mirror reads the same as the clone', async t => {
+  const r = repo(t);
+  const bare = join(r.root, 'mirror.git');
+  git(r.root, 'clone', '-q', '--bare', r.repo, bare);
+  const a = await readLibrary({ repo: r.repo, commit: r.commit, mapping: mapping() });
+  const b = await readLibrary({ repo: bare, commit: r.commit, mapping: mapping() });
+  assert.deepEqual(b, a);
+});
@@ -0,0 +1,80 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { renderItems, UNREADABLE } from '../src/index.mjs';
+
+const A = 'a'.repeat(40), B = 'b'.repeat(40);
+const cite = (path, lines, quote, commit = A) => ({ path, commit, lines, quote });
+const options = {
+  scopeOf: path => path.includes('/Playground/') ? 'playground' : path.endsWith('.md') ? 'canon' : undefined,
+  changed: ({ path, commit }) => path === 'Book One/Characters/Mara Vell.md' && commit === A,
+};
+const render = items => renderItems(JSON.stringify({ items }), options);
+
+// One snapshot per item kind: the plain text both channels show.
+const SNAPSHOTS = {
+  fact: [{ kind: 'fact', text: 'Tomas is the ferryman.', cites: [cite('Book One/Characters/Tomas.md', [3, 3], 'the ferryman', B)] }],
+  finding: [{ kind: 'finding', text: 'Eye colour differs.', cites: [cite('Book One/Chapters/Chapter 01.md', [41, 41], 'her grey eyes'),
+    cite('Book One/Characters/Mara Vell.md', [9, 10], 'green eyes')] }],
+  correction: [{ kind: 'correction', text: 'Chapter 1 says grey.', from: 'green eyes', to: 'grey eyes',
+    cites: [cite('Book One/Characters/Mara Vell.md', [9, 9], 'green eyes', B)] }],
+  question: [{ kind: 'question', text: 'Is the harbor north of the town?', cites: [cite('Book One/Places/Harbor Town.md', [2, 4], 'the harbor', B)] }],
+  idea: [{ kind: 'idea', text: 'A storm could close the harbor.', cites: [cite('Book One/Playground/What If.md', [5, 5], 'a storm', B),
+    { url: 'https://example.invalid/tides', quote: 'spring tides' }] }],
+};
+const EXPECTED = {
+  fact: '1. Fact: Tomas is the ferryman.\n   [canon] Book One/Characters/Tomas.md:3 @bbbbbbb "the ferryman"',
+  finding: '1. Finding: Eye colour differs.\n   [canon] Book One/Chapters/Chapter 01.md:41 @aaaaaaa "her grey eyes"\n'
+    + '   [canon] Book One/Characters/Mara Vell.md:9-10 @aaaaaaa "green eyes" (changed since)',
+  correction: '1. Correction: Chapter 1 says grey.\n   From: "green eyes"\n   To: "grey eyes"\n'
+    + '   [canon] Book One/Characters/Mara Vell.md:9 @bbbbbbb "green eyes"',
+  question: '1. Question: Is the harbor north of the town?\n   [canon] Book One/Places/Harbor Town.md:2-4 @bbbbbbb "the harbor"',
+  idea: '1. Idea: A storm could close the harbor.\n   [playground] Book One/Playground/What If.md:5 @bbbbbbb "a storm"\n'
+    + '   [web] https://example.invalid/tides "spring tides"',
+};
+
+for (const kind of Object.keys(SNAPSHOTS)) {
+  test(`renderItems snapshot: ${kind}`, () => {
+    const out = render(SNAPSHOTS[kind]);
+    assert.equal(out.kind, 'items');
+    assert.equal(out.text, EXPECTED[kind]);
+    assert.equal(out.items[0].kind, kind);
+  });
+}
+
+test('renderItems numbers several items and takes a parsed body as well as a string', () => {
+  const items = [...SNAPSHOTS.fact, ...SNAPSHOTS.question];
+  const out = renderItems({ items }, options);
+  assert.equal(out.text, `${EXPECTED.fact}\n${EXPECTED.question.replace(/^1\./, '2.')}`);
+  assert.deepEqual(out.items[1].cites[0], { badge: 'canon', path: 'Book One/Places/Harbor Town.md', commit: B, lines: [2, 4],
+    ref: 'Book One/Places/Harbor Town.md:2-4 @bbbbbbb', quote: 'the harbor', changed: false });
+});
+
+test('without options a path cite has no badge and is never marked changed', () => {
+  assert.equal(renderItems({ items: SNAPSHOTS.finding }).text,
+    '1. Finding: Eye colour differs.\n   Book One/Chapters/Chapter 01.md:41 @aaaaaaa "her grey eyes"\n'
+    + '   Book One/Characters/Mara Vell.md:9-10 @aaaaaaa "green eyes"');
+});
+
+const NOTICE_SNAPSHOTS = { 'no-cited-answer': 'No cited answer', 'no-answer': 'No answer', 'turn-failed': 'The turn failed' };
+for (const [notice, text] of Object.entries(NOTICE_SNAPSHOTS)) {
+  test(`renderItems snapshot: notice ${notice}`, () => {
+    assert.deepEqual(renderItems(JSON.stringify({ items: [], notice }), options), { kind: 'notice', notice, text });
+  });
+}
+
+test('a body without the reply shape shows a fixed line and none of its text', () => {
+  const secret = 'free prose the guard would refuse';
+  const bodies = [secret, JSON.stringify(secret), '{"items": [], "notice": "other"}', JSON.stringify({ items: [], notice: 'no-answer', extra: secret }),
+    JSON.stringify({ items: [] }), JSON.stringify({ items: [{ kind: 'story', text: secret, cites: [] }] }),
+    JSON.stringify({ items: [{ kind: 'fact', text: secret }] }), JSON.stringify({ items: SNAPSHOTS.fact, prose: secret }),
+    JSON.stringify({ items: [{ kind: 'correction', text: secret, cites: [] }] }),
+    JSON.stringify({ items: [{ kind: 'fact', text: secret, cites: [cite('a.md', [2, 1], 'q')] }] }),
+    JSON.stringify({ items: [{ kind: 'fact', text: secret, cites: [{ path: 'a.md', commit: 'abc', lines: [1, 1], quote: 'q' }] }] }),
+    JSON.stringify({ items: [{ kind: 'fact', text: secret, cites: [{ url: 'https://x.invalid', path: 'a.md', quote: 'q' }] }] }),
+    null, 42, '[]'];
+  for (const body of bodies) {
+    const out = renderItems(body, options);
+    assert.deepEqual(out, { kind: 'unreadable', text: UNREADABLE }, String(body));
+    assert.ok(!JSON.stringify(out).includes(secret));
+  }
+});
@@ -0,0 +1,82 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { writeFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { spawnSync } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
+import { surveyMain } from '../src/index.mjs';
+import { BASE, FIXTURES, MARKER, repo } from './helpers.mjs';
+
+const ROOT = fileURLToPath(new URL('../../..', import.meta.url));
+async function run(args) {
+  let stdout = '', stderr = '';
+  const code = await surveyMain(args, { stdout: { write: s => { stdout += s; } }, stderr: { write: s => { stderr += s; } } });
+  return { code, stdout, stderr };
+}
+// Strings from the fixture that are text, values, file names or link targets: none may be printed.
+const NEVER = [MARKER, 'Grey eyes', 'The Ferryman', 'Mara Vell', 'Tomas', 'Harbor Town', 'What If', 'Inbox Note', 'Chapter 01',
+  'Sketch', 'Board', 'Not A Link', 'the harbor', 'Docks', 'character'];
+
+test('the survey prints folder names, counts, key sets and link-form counts, and never text', async t => {
+  const r = repo(t, { ...BASE, 'Book One/Places/Odd.md': ['---', `"${MARKER} key": 1`, '---', ''].join('\n') });
+  const out = await run(['survey', r.repo]);
+  assert.equal(out.code, 0, out.stderr);
+  assert.equal(out.stdout, [
+    `commit ${r.commit}`,
+    'entries 10',
+    'folders (direct children: md canvas base other)',
+    '  (root) 1 0 0 0',
+    '  "Book One" 0 1 0 0',
+    '  "Book One/Chapters" 1 0 0 0',
+    '  "Book One/Characters" 2 0 0 0',
+    '  "Book One/Places" 2 0 0 0',
+    '  "Book One/Playground" 1 1 0 0',
+    '  "Second World/Chapters" 1 0 0 0',
+    'markdown 8 files, 8 read, 3 without front matter, 0 with front matter not fully parsed',
+    'front matter key sets',
+    '  1 [(other key)]',
+    '  1 [appears_in, name, relationships, type]',
+    '  1 [appears_in, name, type]',
+    '  1 [name]',
+    '  1 [type]',
+    'body links plain 3, label 1, heading 1, embed 0, self 0, markdown 1',
+    'field appears_in wikilink 2, name 0',
+    'field relationships wikilink 1, name 1',
+    ''].join('\n'));
+  for (const s of NEVER) assert.ok(!out.stdout.includes(s), s);
+});
+
+test('with --mapping the survey adds scope, resolver step and problem counts', async t => {
+  const r = repo(t);
+  const out = await run(['survey', r.repo, '--mapping', join(FIXTURES, 'mapping.json')]);
+  assert.equal(out.code, 0, out.stderr);
+  const tail = out.stdout.trimEnd().split('\n').slice(-3);
+  assert.deepEqual(tail, [
+    'scopes canon 5, playground 1, unmapped 3; indexed 6',
+    'resolved root 2, vault-prefix 1, relative 2, shortest 3, unresolved 0',
+    'problems R1 0, R2 3, R3 0, R4 0, R5 0, R6 0, R7 0']);
+  for (const s of NEVER) assert.ok(!out.stdout.includes(s), s);
+});
+
+test('survey exit codes: usage 4, bad mapping 3, unreadable repo 2', async t => {
+  const r = repo(t);
+  for (const args of [[], ['scan', r.repo], ['survey'], ['survey', r.repo, '--mapping'], ['survey', r.repo, '--other'], ['survey', r.repo, r.repo]])
+    assert.equal((await run(args)).code, 4, args.join(' '));
+  const bad = join(r.root, 'bad.json');
+  writeFileSync(bad, JSON.stringify({ kind: 'library' }));
+  const refused = await run(['survey', r.repo, '--mapping', bad]);
+  assert.equal(refused.code, 3);
+  assert.match(refused.stderr, /library-mapping-invalid/);
+  writeFileSync(bad, 'not json');
+  assert.equal((await run(['survey', r.repo, '--mapping', bad])).code, 3);
+  assert.equal((await run(['survey', join(r.root, 'missing')])).code, 2);
+  assert.equal((await run(['survey', r.root])).code, 2, 'a directory that is not a repo');
+});
+
+test('scripts/mosaic library survey reaches the survey', t => {
+  const r = repo(t);
+  const out = spawnSync(join(ROOT, 'scripts/mosaic'), ['library', 'survey', r.repo], { encoding: 'utf8', timeout: 30000 });
+  assert.equal(out.status, 0, out.stderr);
+  assert.match(out.stdout, new RegExp(`^commit ${r.commit}\n`));
+  assert.ok(!out.stdout.includes(MARKER));
+});
@@ -34,6 +34,12 @@ if [ "${1:-}" = business ]; then
  shift
  exec node "$REPO/packages/business/src/cli.mjs" "$@"
 fi
+# `mosaic library survey`: names and counts from a writing repo, never its text
+# (packages/library/README.md). Other library verbs are bus verbs.
+if [ "${1:-}" = library ] && [ "${2:-}" = survey ]; then
+  shift
+  exec node "$REPO/packages/library/src/survey.mjs" "$@"
+fi
 case "${1:-}" in
  usage|project|limits|inbox|decide|tasks|agents|trail|talk|stop|launches|bus|plugins|name|names|follow|threads|thread) exec node "$REPO/packages/cli/src/cli.mjs" "$@" ;;
 esac
@@ -27,7 +27,7 @@ COPY_PATHS=(
 packages/conversation/src packages/discord/src packages/discord/bin packages/discord/extension packages/harness/src
 packages/seat/src packages/tasks/src packages/tasks/fields.json packages/tasks/requirements.json
 packages/webui/src packages/webui/README.md packages/cli/README.md
- packages/queue/src
+ packages/queue/src packages/library/src
 # Whole directory: every in-repo plug-in module ships with the copy (row 131).
 packages/plugins
 )