researcher: row 216 r5, index-build test makes Book One/Places before the write and query test lists the hybrid paths in sorted order (mos-1528, sage-3702); tests only, BUILD.md round 4

agents/researcher/work/queue-216/BUILD.md

@@ -0,0 +1,237 @@
+# Row 216 build notes (C2-05a, lookup index and queries, #1717)
+
+Phase A only: code, tests and this file. No test, suite or mutant has been run. `node --check` passed on every changed `.mjs`.
+
+- Branch: `researcher/row216`
+- Base: `d372102882d6858fa77af4aee453f866c886ad5c` (origin/refactor)
+- Design: `agents/gosalyn/work/case2/DESIGN.md` on origin/gosalyn/case2-design, section 3 (table at lines 625-631, bullets 633-641), 1.2-1.4, B12, D2
+- Brief: `docs/plans/2026-10-20_case2-rows.md`, C2-05a at lines 320-357
+
+## Files
+
+| Path | Status |
+|---|---|
+| `packages/library/src/index-build.mjs` | new |
+| `packages/library/src/query.mjs` | new |
+| `packages/library/src/index.mjs` | edit: 2 export lines added |
+| `packages/library/tests/query-fixture.mjs` | new, test helper |
+| `packages/library/tests/query.test.mjs` | new |
+| `packages/library/tests/index-build.test.mjs` | new |
+| `agents/researcher/work/queue-216/BUILD.md` | new (this file) |
+
+No existing test or source file changed beyond `index.mjs`.
+
+## Design rows and where each is tested
+
+| Design row | Code | Tests (query.test.mjs unless noted) |
+|---|---|---|
+| `library_find` | `find` | find is bound to its universe; every result carries its scope; long list pages; large items page under the cap |
+| `library_get` | `get` | hybrid gets a source file; get lists visible links both ways; get pages its lines |
+| `library_search` | `search` | search returns scoped line hits; item that cannot fit alone is refused |
+| `library_manuscript` | `manuscript` | one chapter at most 400 lines; refused without chapter; hybrid reads a source chapter |
+| `library_universe` | `universeInfo` | universe info reports a hybrid's sources, constraints, notes; unknown universe refused |
+| Hybrid semantics (1.4) | `sees` | a hybrid sees its sources canon minus exclusions, no playground |
+| Unmapped never appears | index build + `sees` | unmapped files never appear (query.test); index holds mapped files only (index-build.test) |
+| Per-commit cache (3) | `indexFor` | same commit, path, mapping return one index; different path, mapping or commit get their own; eight-entry bound; failed read not kept; unchecked mapping refused (index-build.test) |
+| Rebuild time (3, C2-05a gate) | `indexFor` | 3,000-file rebuild, time reported with `t.diagnostic`, no threshold asserted |
+| REPLY_CAP parity | `QUERY_REPLY_CAP` | equals `REPLY_CAP` from harness tools.mjs |
+
+## Choices where the design table is silent or differs
+
+These are departures or gaps. Each is built as stated, so Sage can rule before Phase B. A ruling that changes one of them is a small edit.
+
+1. **Paging arguments (gap a).** The table has no offset. `find` and `search` take an optional `offset` (a position in the filtered list, default 0). A reply carries `next`: the position of the next item, or `null`.
+2. **`library_get` has no universe (gap b).** Built with a required `universe`. Without it the reply could not be isolated. A missing file and a file the universe cannot see both return `null`, so a caller cannot tell them apart. `get` also takes an optional `from` line.
+3. **`get` over the cap (gap c).** Lines page by `from` with `next`. `links_out` and `links_in` come back whole on every page. If the frontmatter and links alone exceed the cap, the call is refused with `query-item-too-large`. A hub note with many backlinks may be refused. This needs a ruling: link paging, or accept the refusal.
+4. **`manuscript` without a chapter (gap d).** Refused with `query-chapter-required`. The design names no list form. A chapter name that matches two visible files is refused with `query-chapter-ambiguous`.
+5. **`search` excerpt (gap e).** The excerpt is the whole line, not a truncation. A line that alone exceeds the cap is refused. Truncating it would cut an item.
+6. **`exclude` form (gap f).** `checkMapping` accepts only a folder path for `exclude` (`folder()`), so an exclusion is a path prefix. There is no type or source form to build. Confirm.
+7. **Pin constraints.** `pin` does not hide any file. It is reported by `universeInfo` only. Confirm.
+8. **Playground through `get`.** `scope` applies to lists. `get` by an explicit path returns a playground file of the caller's own universe. Confirm.
+9. **Links.** A link into a file the universe cannot see is dropped from `links_out` and `links_in`, in line with N1. Links from a visible file that point into another universe are kept in the index (the reader keeps them under R6), and the query layer drops them for universes that cannot see them.
+10. **`find` matching.** Case-insensitive substring over the front matter `name` and the file name. An empty `query` matches every file in scope.
+11. **Cache key.** `repo`, `commit` and a sha256 of the canonical mapping. Keying by commit alone would return the wrong scopes after a mapping change. The cache holds eight entries, least recently used out. Failed reads are not kept.
+12. **`universeInfo`.** Reads only the checked mapping and the served commit. It builds no index.
+13. **Reply commit.** Every reply carries the index commit, which is the served commit passed in.
+
+## Provisional refusal codes (pending Sage approval)
+
+The brief says new refusal codes need Sage's approval first. These are provisional and must not be treated as settled:
+
+- `query-argument-invalid`
+- `query-universe-unknown`
+- `query-chapter-required`
+- `query-chapter-ambiguous`
+- `query-item-too-large`
+
+Reused, existing codes: `library-mapping-invalid`, plus the reader's `library-git`, `library-commit` through `indexFor`.
+
+## Grep results (grep only, not a test run)
+
+- Test references to the changed paths: `packages/library/tests/*.mjs` import `../src/index.mjs` and `../src/mapping.mjs`. `packages/bus/tests/library.test.mjs` and `library-sync.test.mjs` import the library index as a namespace. Neither enumerates its exports, so the two new export lines break no assertion.
+- `packages/cli/tests/stack-copy.test.mjs:52` checks that `packages/library/src/index.mjs` exists, and it still does.
+- 64-hex pins: none in `packages/library/tests`, none on `index.mjs`, `query.mjs` or `index-build.mjs`.
+- `scripts/test-*.sh`: no reference to the new modules.
+
+## Flag for Sage
+
+- `packages/library/tests/helpers.mjs` `repo()` builds its fixtures under `tmpdir()`, which is `/tmp`. The launcher rules forbid that. The new tests do not use it; they use `tests/query-fixture.mjs`, which builds under `/mnt/storage/scratch/tmp`. The existing helper should be fixed in a separate row, not here.
+
+## Phase B commands (not run)
+
+Run only after Sage sends "slot clear". Set the scratch TMPDIR first, per the launcher rule.
+
+```
+cd /mnt/storage/src/mosaic-stack/.claude/worktrees/agent-aa3cc98787bc5152c/packages/library
+export TMPDIR=/mnt/storage/scratch/tmp
+node --test tests/query.test.mjs tests/index-build.test.mjs
+node --test tests/*.test.mjs
+```
+
+Also run `packages/bus/tests/library.test.mjs` and `library-sync.test.mjs`, since they import the index.
+
+## Status
+
+Not yet verified. Nothing has been tested and nothing is committed. The working tree holds the Phase A changes. AGENTS.md invariant 8 allows a commit only after the applicable suites are green, so the commit waits for Phase B. The dispatch asked for a local commit in Phase A; Sage to confirm that the commit waits for Phase B.
+
+## Round 2 (2026-10-22, sage-2708, sage-2716): rulings applied, rebased onto aca16404c
+
+Added after the text above; nothing above is edited. "Nothing is committed", "Provisional refusal codes",
+`query-chapter-required` and the tmpdir flag above were true when written and are superseded here.
+
+- Branch `researcher/row216-r2`, one local commit on origin/refactor `aca16404c`. Row 268 (C2-01c) is in
+  that base. Row 253 has not landed; the work rebases onto 253's tip before any gate. Not pushed, not run.
+- Rulings: `agents/sage/work/queue-216/RULINGS.md` at da9555ca2, rulings 1-13 and the tmpdir flag.
+- Drift check, d37210288..aca16404c against my paths: the library files that changed are `mapping.mjs`,
+  `scope.mjs`, `README.md` and the mapping and scope tests. None is a file I add or edit. `query.mjs` reads
+  the checked mapping through them, so the whole library package runs in phase B.
+
+### What changed from phase A
+
+| Ruling | Change in `query.mjs` | Test |
+|---|---|---|
+| 3 `get` over the cap | `links_out` and `links_in` page together with `links_from`; every reply carries `links_next`, `next` and the front matter. A page with lines left carries at least one line. Links take at most half the cap while lines remain. `query-item-too-large` is left for front matter alone or one line alone (or one link alone) | hub note with 900 backlinks pages and adds up; front matter alone and a line alone refused; bad `links_from` |
+| 4 `manuscript` no chapter | `chapter` optional: the first visible chapter in path order. Every reply carries `next_chapter`. `query-chapter-required` removed. Ambiguity still refuses | first chapter and `next_chapter`; ambiguous name refused |
+| 5 `search` long line | hit comes back `{path, line, excerpt: null, excerpt_too_long: true, scope}`, other hits still return | marked hit and unmarked hits in one reply |
+| 6 `exclude` | path-prefix reading only. The test names `EXCLUSION` and `EXCLUDED_PATHS` in `query-fixture.mjs`, so C2-15 (row 267) swaps two constants | exclusion hides from the hybrid and not from the source |
+| 8 hybrid `get` | unchanged code; test added | hybrid gets a source's playground file as `null`; the source gets it with `scope: "playground"` |
+| PRD 1.14 (row 268) | `universeInfo` reports `kind` from the mapping (`draft` included) | four tests below |
+
+PRD 1.14 tests, one each: a lookup naming a `book` leaves `book: null` files out (find and search);
+`library_manuscript` never reads a `book: null` file; a draft universe has no canon, so its lookups return
+files only with `scope: "playground"`; `library_universe` on a draft returns kind, name and prefixes.
+The levels fixture is `WITH_LEVELS` in `query.test.mjs`: harbor gets `Notes/Harbor/` as a universe-level
+playground prefix, and `idea` is a draft over `Drafts/New World/`.
+
+`query-fixture.mjs` builds under `tmpdir()`, as `helpers.mjs` does (ruling "tmpdir flag"). The earlier
+flag about `helpers.mjs` building under `/tmp` is closed by that ruling: the gate sets `TMPDIR`.
+
+Refusal codes now: `query-argument-invalid`, `query-universe-unknown`, `query-chapter-ambiguous`,
+`query-item-too-large`. All four approved in the rulings.
+
+### Grep results (grep only, not a test run)
+
+- `git grep` over `packages/*/tests/*` and `scripts/*` for `query.mjs` and `index-build`: no hit outside
+  `packages/library/tests/query*.test.mjs` and `index-build.test.mjs`.
+- 64-hex pins naming a library path: none. Positive control: the same pathspec finds the sha256 lines in
+  `packages/cli/tests/case1-hostcheck.test.mjs` and the `packages/library/src/index.mjs` existence check at
+  `packages/cli/tests/stack-copy.test.mjs:52`.
+- Tests that read `packages/library/src` as a directory: `packages/cli/tests/stack-release-fixture.mjs:309`
+  copies `packages/library/src` whole into a release fixture. It carries no file list, so two new files break
+  no assertion. `stack-release.test.mjs` is not in the gate unless Sage wants it.
+- Tests that import the library index as a namespace: `packages/bus/tests/library.test.mjs` and
+  `library-sync.test.mjs`. Neither enumerates exports, so the two export lines add no break. Both run
+  whole in phase B.
+
+### Run limits (fixed before any run)
+
+Every node file runs as its own `setsid -w timeout -k 10 LIMIT node --test FILE`; nothing runs unbounded.
+
+- Node test files: LIMIT 900 s. The library test files have no recorded time. 900 s is above the longest
+  recorded whole-package run I know of (cli, 591 s, row 281 BUILD.md "Runs" step 3), so it holds the 3x rule
+  for any single file. The first run records each file's time, and a file past 300 s gets a limit re-derived
+  from it before the next run. `query.test.mjs` builds a 900-file repo and a 3,000-file index rebuild is in
+  `index-build.test.mjs`; both are the files most likely to need it.
+- No shell script is in this row's gate, so no script limit applies.
+
+Any timeout goes to Sage, then Mos, unplaced (mos-1275).
+
+### Phase B (not run; Sage's CLEAR first, then a rebase onto 253's tip)
+
+```
+export TMPDIR=/mnt/storage/scratch/tmp
+cd <worktree>/packages/library
+for f in tests/*.test.mjs; do setsid -w timeout -k 10 900 node --test "$f"; done
+cd ../bus
+for f in tests/library.test.mjs tests/library-sync.test.mjs; do setsid -w timeout -k 10 900 node --test "$f"; done
+cd ../cli
+setsid -w timeout -k 10 900 node --test tests/stack-copy.test.mjs
+```
+
+Mutants I propose (my list, not read off the brief; each is meant to be killed by the named test, and none
+has been thrown; the kill claims are unverified until CLEAR):
+
+- M-a: `sees()` returns true for a file of another universe: killed by "find is bound to its universe".
+- M-b: the playground filter dropped: killed by "playground appears only when asked for".
+- M-c: the hybrid reads a source's playground: killed by "a hybrid gets a source playground file as null".
+- M-d: `links_next` always null: killed by the hub paging test.
+- M-e: the book filter lets `book: null` through: killed by the PRD 1.14 book test.
+
+### Status
+
+Built, not run. `node --check` has not been run on this round's files (no node before the CLEAR); the
+phase A pass above covered the earlier text only. The commit is local and waits for no gate under Sage's
+sage-2716 instruction, which allows git and docs work only; push and claim wait for Sage's go.
+
+## Round 3: rebase onto 45dca69f6, drift check, hash-pin grep (2026-10-23T18:53:43Z, sage-3576)
+
+Appended; nothing above is edited. Git only; nothing run, nothing pushed. Branch researcher/row216-r4 holds the
+one row 216 commit on 45dca69f6 (origin/refactor, 10-23). Earlier base: 48e450ce8 (row 253).
+
+- Rebase: clean. `git range-diff 48e450ce8..038089e5f 45dca69f6..researcher/row216-r4` shows the commit as `=`.
+- Landed in 48e450ce8..45dca69f6: 1175 files. Path overlap with this row's 7 paths: none. packages/library: no
+  landed file. packages/harness/src/tools.mjs (imported by query-fixture.mjs or the tests): not landed.
+- Hash-pin grep (the item 216 owed): 64-hex in packages/library: none. Positive control: 364 files in
+  packages/*/tests and scripts match 64-hex. Tests and scripts that name library files by path:
+  bus/tests/library.test.mjs and library-sync.test.mjs and bus/src/runtime.mjs import library/src/index.mjs;
+  business/src/business.mjs and its test import library/src/mapping.mjs (unchanged by this row);
+  cli/tests/stack-copy.test.mjs, stack-release-fixture.mjs:310 and stack-release.test.mjs:1991 copy
+  packages/library/src as a tree; scripts/stack-copy.sh:37 copies it; scripts/mosaic:41 runs survey.mjs. None pins
+  a hash of index.mjs, index-build.mjs or query.mjs.
+- bus/src/runtime.mjs landed changes after 48e450ce8 and uses libraryModule by named members (ensureMirror, SLOT,
+  readLibraryFile, libraryStatus, sync, LibraryError, SYNC_INTERVAL_MS) only; the landed diff touches none of them,
+  and this row's two new index.mjs exports (query and index build) are not iterated by any caller.
+- Gate additions for phase B: run bus library.test.mjs and library-sync.test.mjs whole (they import index.mjs), and
+  the cli stack-copy and stack-release tests that copy packages/library/src.
+
+## Round 4: phase B on 4e5d28ab2, two test fixes for r5 (2026-10-23T20:20:51Z, sage-3702, mos-1528)
+
+Appended; nothing above is edited.
+
+Phase B receipts on 4e5d28ab2 (researcher-r216-kit/out-b1): library whole 114 pass, 2 fail; bus library.test and
+library-sync.test 12 pass; cli 266 pass. The 3,000-file rebuild took 3807 ms (the test, with fixture setup, 4070 ms;
+`t.diagnostic` in index-build.test.mjs). No row 216 mutant was required or thrown in that round.
+
+The 2 library reds are test faults, not product faults. Both are placed as first-run reds in files this row adds
+(mos-1272); Mos ruled both fixes in mos-1528 and Sage relayed it in sage-3712.
+
+- R4: `packages/library/tests/index-build.test.mjs`, test "a different repo path, mapping or commit gets its own
+  index". Old: `writeFileSync(join(repo, 'Book One/Places/New.md'), …)` with no `Book One/Places` folder in FILES, so
+  the write failed with ENOENT. New: one `mkdirSync(join(repo, 'Book One/Places'), { recursive: true })` before the
+  write (import line gains `mkdirSync`). No assertion changes.
+- R5: `packages/library/tests/query.test.mjs`, test "a hybrid sees its sources canon, minus exclusions, and no
+  playground". The assertion sorts the actual paths and compared them to an unsorted literal, so the literal had
+  the wrong order (Characters before Chapters; Second World Characters before Chapters). New: only the expected
+  literal is reordered into sorted order. The `.sort()` on the actual side stays, and the assertion still checks
+  order. The set of seven paths is unchanged.
+- Product code: no edit.
+
+Reruns owed after the r5 commit (run on Sage's CLEAR, after the 283 gate): index-build.test.mjs whole,
+query.test.mjs whole, library whole, and the mutants those two files kill (M-a to M-e above). Results are appended
+below as a new entry.
+
+Run limit note: stack-release.test.mjs ran 644 s in the cli run. A per-file limit of 3 x 644 = 1932 s covers it.
+Sage's gates run cli as one whole-package `node --test` under 2100 s.
+
+Carry notes from Filbert's static check (doc only, no change in r5): N1 and N2 stay recorded as he gave them. The
+`After` list in this file still names row 268; row 268 landed at c27207f6e.

packages/library/src/index-build.mjs

@@ -0,0 +1,75 @@
+// The lookup index of design 3 (C2-05a): types, names, links and backlinks for one commit of her repo.
+// It is built from the reader's output, so it holds only mapped, readable files: R1, R2 and R7 leave a
+// file out, and an unresolved link is not in it. It is cached in memory by commit id. The key also
+// carries the repo path and a digest of the mapping, because one commit reads differently under another
+// mapping. The index is not universe-aware; query.mjs decides what a universe may see.
+import { createHash } from 'node:crypto';
+import { readLibrary } from './reader.mjs';
+import { raise } from './problems.mjs';
+
+const CACHE_LIMIT = 8;
+const cache = new Map();
+
+const push = (map, key, value) => {
+  if (!map.has(key)) map.set(key, []);
+  map.get(key).push(value);
+};
+// A file's name for lookups: its front matter `name` when it is text, else its file name.
+const displayName = file => {
+  const name = file.frontmatter?.name;
+  return typeof name === 'string' && name.trim() ? name.trim() : file.name;
+};
+// A link as the index keeps it: the file at the other end, its line, and the field when front matter holds it.
+const linkAt = (path, link) => ({ path, line: link.line, ...(link.field === undefined ? {} : { field: link.field }) });
+
+// Builds the index from readLibrary's output. Pure: no git, no clock.
+export function buildIndex(library, mapping) {
+  const files = new Map(), types = new Map(), names = new Map(), linksOut = new Map(), linksIn = new Map();
+  for (const file of library.files) {
+    const name = displayName(file);
+    files.set(file.path, {
+      path: file.path, scope: file.scope, universe: file.universe, book: file.book, type: file.type,
+      folder: file.folder, stem: file.name, name, frontmatter: file.frontmatter, lines: file.lines,
+    });
+    if (file.type !== null) push(types, file.type, file.path);
+    push(names, name.toLowerCase(), file.path);
+    linksOut.set(file.path, file.links.map(link => linkAt(link.path, link)));
+    for (const link of file.links) push(linksIn, link.path, linkAt(file.path, link));
+  }
+  return Object.freeze({
+    commit: library.commit, mapping, files, paths: [...files.keys()], types, names, linksOut, linksIn,
+    problems: library.problems,
+  });
+}
+
+const digest = mapping => createHash('sha256').update(JSON.stringify(mapping)).digest('hex');
+
+// The index for one commit under one mapping, read once and kept in memory. A repeat call returns the same
+// object. Past CACHE_LIMIT entries the oldest goes. A failed read is not kept.
+export async function indexFor({ repo, commit, mapping }) {
+  if (!mapping || mapping.kind !== 'library') raise('library-mapping-invalid', 'expected a checked library mapping');
+  const key = JSON.stringify([repo, commit, digest(mapping)]);
+  if (cache.has(key)) {
+    const hit = cache.get(key);
+    cache.delete(key);
+    cache.set(key, hit);
+    return hit;
+  }
+  const pending = readLibrary({ repo, commit, mapping }).then(library => buildIndex(library, mapping));
+  cache.set(key, pending);
+  while (cache.size > CACHE_LIMIT) cache.delete(cache.keys().next().value);
+  try {
+    return await pending;
+  } catch (error) {
+    if (cache.get(key) === pending) cache.delete(key);
+    throw error;
+  }
+}
+
+export function clearIndexCache() {
+  cache.clear();
+}
+
+export function indexCacheSize() {
+  return cache.size;
+}

packages/library/src/index.mjs

@@ -8,3 +8,5 @@ export { renderItems, KINDS, NOTICES, UNREADABLE } from './render.mjs';
 export { survey, formatSurvey, surveyMain } from './survey.mjs';
 export { SYNC_STATE_FILE, mirrorPath, ensureMirror, withLibraryLock, servedCommit, readSyncState, libraryStatus, readLibraryFile } from './mirror.mjs';
 export { syncCommand, sync, ASKPASS, SLOT, SYNC_INTERVAL_MS } from './sync.mjs';
+export { buildIndex, indexFor, clearIndexCache, indexCacheSize } from './index-build.mjs';
+export { sees, find, get, search, manuscript, universeInfo, QUERY_REPLY_CAP, LOOKUP_LIMIT, MANUSCRIPT_LINES } from './query.mjs';

packages/library/src/query.mjs

@@ -0,0 +1,240 @@
+// The lookup queries of design 3 (C2-05a): find, get, search, manuscript and universeInfo. Each takes a
+// source {repo, commit, mapping} and an argument object, and returns a reply that fits QUERY_REPLY_CAP.
+// Universe isolation is here, in sees(): a file reaches a reply only when sees() allows it. Scope comes
+// from the path (D2). Unmapped files are not in the index, so they never appear. Lists page by position
+// and never cut an item. A search line too long to fit alone comes back as a marked hit with no excerpt;
+// a find item, a file's front matter or one of its lines that cannot fit alone is refused.
+import { raise } from './problems.mjs';
+import { TYPES } from './mapping.mjs';
+import { indexFor } from './index-build.mjs';
+
+// The same cap as packages/harness/src/tools.mjs REPLY_CAP. The query tests assert the two stay equal.
+export const QUERY_REPLY_CAP = 40_000;
+export const LOOKUP_LIMIT = 50;
+export const MANUSCRIPT_LINES = 400;
+const SCOPES = Object.freeze(['canon', 'playground']);
+
+const bytes = value => JSON.stringify(value).length;
+const invalid = message => raise('query-argument-invalid', message);
+const inside = (folder, path) => path.startsWith(folder.endsWith('/') ? folder : `${folder}/`);
+
+function textArg(value, name) {
+  if (typeof value !== 'string') invalid(`${name} must be text`);
+  return value;
+}
+function scopeArg(value) {
+  if (value === undefined) return 'canon';
+  if (!SCOPES.includes(value)) invalid('scope must be "canon" or "playground"');
+  return value;
+}
+function positionArg(value, name, fallback) {
+  if (value === undefined) return fallback;
+  if (!Number.isSafeInteger(value) || value < 1) invalid(`${name} must be a line number of 1 or more`);
+  return value;
+}
+function offsetArg(value) {
+  if (value === undefined) return 0;
+  if (!Number.isSafeInteger(value) || value < 0) invalid('offset must be a whole number of 0 or more');
+  return value;
+}
+function universeArg(mapping, value) {
+  if (typeof value !== 'string' || !value) invalid('universe is required');
+  if (!Object.hasOwn(mapping.universes, value)) raise('query-universe-unknown', `this library has no universe ${JSON.stringify(value)}`);
+  return value;
+}
+
+// Whether universe U may see a file. Its own files, in either scope. A hybrid also sees the canon of
+// its declared sources, minus the folders its exclude constraints name. A hybrid never sees a source's
+// playground. Pin constraints do not hide anything; they are reported by universeInfo only.
+export function sees(mapping, universe, file) {
+  if (file.universe === universe) return true;
+  const entry = mapping.universes[universe];
+  if (entry.kind !== 'hybrid' || !entry.sources.includes(file.universe) || file.scope !== 'canon') return false;
+  return !entry.constraints.some(c => c.exclude !== undefined && inside(c.exclude, file.path));
+}
+
+// The files one universe may see in one scope, with optional book and type filters, in path order.
+async function visible(source, universe, { scope, book, type }) {
+  const index = await indexFor(source);
+  const files = index.paths
+    .map(path => index.files.get(path))
+    .filter(file => file.scope === scope && sees(index.mapping, universe, file)
+      && (book === undefined || file.book === book) && (type === undefined || file.type === type));
+  return { index, files };
+}
+
+// A reply whose size is over the cap is refused, never cut.
+function checked(reply) {
+  if (bytes(reply) > QUERY_REPLY_CAP) raise('query-item-too-large', `the reply is over the ${QUERY_REPLY_CAP}-character cap`);
+  return reply;
+}
+
+// Picks items from `offset`, at most `limit`, while the reply still fits. build(picked, next) returns
+// the reply; `next` is the position of the first item not picked, or null when none is left. An item
+// that cannot fit even alone is refused: skipping it would hide it, and cutting it would break it.
+function fitPage(items, { offset = 0, limit = LOOKUP_LIMIT, build }) {
+  const picked = [];
+  let at = offset;
+  while (at < items.length && picked.length < limit) {
+    // The size check uses items.length for `next`, the widest number a cursor can take, so a page never runs over.
+    if (bytes(build([...picked, items[at]], items.length)) > QUERY_REPLY_CAP) {
+      if (!picked.length) raise('query-item-too-large', `the item at position ${at} alone is over the ${QUERY_REPLY_CAP}-character cap`);
+      break;
+    }
+    picked.push(items[at]);
+    at += 1;
+  }
+  return checked(build(picked, at < items.length ? at : null));
+}
+
+// find: the files whose name or file name holds `query`, case-insensitive. Up to 50 per page.
+export async function find(source, { universe: name, query, type, book, scope, offset } = {}) {
+  const universe = universeArg(source.mapping, name);
+  const needle = textArg(query, 'query').toLowerCase();
+  if (type !== undefined && !TYPES.includes(type)) invalid(`type must be one of ${TYPES.join(', ')}`);
+  const { index, files } = await visible(source, universe, {
+    scope: scopeArg(scope), book: book === undefined ? undefined : textArg(book, 'book'), type,
+  });
+  const hits = files.filter(file => file.name.toLowerCase().includes(needle) || file.stem.toLowerCase().includes(needle));
+  return fitPage(hits, {
+    offset: offsetArg(offset),
+    build: (picked, next) => ({
+      commit: index.commit,
+      results: picked.map(file => ({
+        path: file.path, type: file.type, name: file.name, appears_in: file.frontmatter?.appears_in ?? null,
+        scope: file.scope, universe: file.universe, book: file.book,
+      })),
+      next,
+    }),
+  });
+}
+
+// get: one visible file, its front matter, its lines from `from`, and its visible links both ways.
+// Returns null when the file is missing or not visible, so a caller cannot tell the two apart. Lines page
+// by `from` (reply `next`), links page together by `links_from` (reply `links_next`); `links_out` come
+// before `links_in`. Every page carries the front matter. Links take at most half the cap, so a hub note
+// with many backlinks stays readable and still leaves room for lines. A page with lines left carries at
+// least one line, so links shrink when a line needs the room; read on with `from: next` and
+// `links_from: links_next`. A `from` past the last line returns links alone. Only front matter, or a
+// line that cannot fit with no links beside it, is refused.
+export async function get(source, { universe: name, path, from, links_from: linksFrom } = {}) {
+  const universe = universeArg(source.mapping, name);
+  const startLine = positionArg(from, 'from', 1);
+  const linkStart = offsetArg(linksFrom);
+  if (typeof path !== 'string') invalid('path must be text');
+  const index = await indexFor(source);
+  const file = index.files.get(path);
+  if (!file || !sees(index.mapping, universe, file)) return null;
+  const reachable = links => links.filter(link => {
+    const other = index.files.get(link.path);
+    return other !== undefined && sees(index.mapping, universe, other);
+  });
+  const outs = reachable(index.linksOut.get(file.path) ?? []);
+  const ins = reachable(index.linksIn.get(file.path) ?? []);
+  const links = [...outs.map(link => ({ out: true, link })), ...ins.map(link => ({ out: false, link }))];
+  const lines = file.lines.slice(startLine - 1);
+  const linkRest = Math.max(0, links.length - linkStart);
+  const page = (nLines, nLinks) => {
+    const taken = links.slice(linkStart, linkStart + nLinks);
+    return {
+      path: file.path, commit: index.commit, scope: file.scope, frontmatter: file.frontmatter,
+      lines: lines.slice(0, nLines),
+      links_out: taken.filter(item => item.out).map(item => item.link),
+      links_in: taken.filter(item => !item.out).map(item => item.link),
+      next: nLines < lines.length ? startLine + nLines : null,
+      links_next: nLinks < linkRest ? linkStart + nLinks : null,
+    };
+  };
+  // How many leading items fit in `room`, by each item's own size.
+  const count = (items, room) => {
+    let used = 0, n = 0;
+    while (n < items.length && used + bytes(items[n]) + 1 <= room) used += bytes(items[n++]) + 1;
+    return n;
+  };
+  const base = bytes(page(0, 0));
+  if (base > QUERY_REPLY_CAP) raise('query-item-too-large', `the front matter of ${file.path} alone is over the ${QUERY_REPLY_CAP}-character cap`);
+  if (lines.length && bytes(page(1, 0)) > QUERY_REPLY_CAP) {
+    raise('query-item-too-large', `line ${lines[0][0]} of ${file.path} alone is over the ${QUERY_REPLY_CAP}-character cap`);
+  }
+  const rest = links.slice(linkStart);
+  let nLinks = count(rest, (lines.length ? Math.floor(QUERY_REPLY_CAP / 2) : QUERY_REPLY_CAP) - base);
+  if (!nLinks && rest.length) nLinks = count(rest, QUERY_REPLY_CAP - base);
+  if (!nLinks && rest.length) raise('query-item-too-large', `a link of ${file.path} alone is over the ${QUERY_REPLY_CAP}-character cap`);
+  while (lines.length && nLinks > 0 && bytes(page(1, nLinks)) > QUERY_REPLY_CAP) nLinks = Math.floor(nLinks / 2);
+  let nLines = Math.max(lines.length ? 1 : 0, count(lines, QUERY_REPLY_CAP - bytes(page(0, nLinks))));
+  while (nLines > 1 && bytes(page(nLines, nLinks)) > QUERY_REPLY_CAP) nLines -= 1;
+  return checked(page(nLines, nLinks));
+}
+
+// search: lines whose text holds `text`, case-insensitive. The excerpt is the whole line. Up to 50 per page.
+export async function search(source, { universe: name, text, book, scope, offset } = {}) {
+  const universe = universeArg(source.mapping, name);
+  const needle = textArg(text, 'text').toLowerCase();
+  if (!needle) invalid('text must not be empty');
+  const { index, files } = await visible(source, universe, {
+    scope: scopeArg(scope), book: book === undefined ? undefined : textArg(book, 'book'),
+  });
+  const hits = [];
+  for (const file of files) {
+    for (const [line, body] of file.lines) {
+      if (!body.toLowerCase().includes(needle)) continue;
+      const hit = { path: file.path, line, excerpt: body, scope: file.scope };
+      // The excerpt is the whole line. A line too long to fit alone is marked, not cut and not refused.
+      hits.push(bytes({ commit: index.commit, results: [hit], next: Number.MAX_SAFE_INTEGER }) > QUERY_REPLY_CAP
+        ? { path: file.path, line, excerpt: null, excerpt_too_long: true, scope: file.scope } : hit);
+    }
+  }
+  return fitPage(hits, {
+    offset: offsetArg(offset),
+    build: (picked, next) => ({ commit: index.commit, results: picked, next }),
+  });
+}
+
+// manuscript: one chapter file of a book, by its file name, up to 400 lines per call from `from` to `to`.
+// Without a chapter it returns the book's first chapter file in path order. Every reply carries
+// `next_chapter`, the next chapter file's name in path order or null. A name that matches two visible
+// files is refused. Files outside every book (book null) are never chapters of a book.
+export async function manuscript(source, { universe: name, book, scope, chapter, from, to } = {}) {
+  const universe = universeArg(source.mapping, name);
+  const bookName = textArg(book, 'book');
+  const chapterName = chapter === undefined ? undefined : textArg(chapter, 'chapter');
+  const start = positionArg(from, 'from', 1);
+  const end = positionArg(to, 'to', Infinity);
+  if (end < start) invalid('to must not be before from');
+  const { index, files } = await visible(source, universe, { scope: scopeArg(scope), book: bookName, type: 'manuscript' });
+  let at = 0;
+  if (chapterName !== undefined) {
+    const matches = files.filter(file => file.stem === chapterName);
+    if (matches.length > 1) raise('query-chapter-ambiguous', `${matches.length} visible files are named ${JSON.stringify(chapterName)}`);
+    if (!matches.length) return null;
+    at = files.indexOf(matches[0]);
+  }
+  const file = files[at];
+  if (!file) return null;
+  const nextChapter = files[at + 1]?.stem ?? null;
+  return fitPage(file.lines.slice(start - 1, end), {
+    limit: MANUSCRIPT_LINES,
+    build: (picked, next) => ({
+      path: file.path, commit: index.commit, scope: file.scope, lines: picked,
+      next: next === null ? null : start + next, next_chapter: nextChapter,
+    }),
+  });
+}
+
+// universeInfo: a universe's kind, name, books, playground prefixes, type folders and manuscript folders.
+// A hybrid adds its sources, constraints and notes. A draft has no books and no canon: its kind, name
+// and prefixes are the whole answer beside the mapping's types. It reads only the checked mapping and the
+// served commit.
+export async function universeInfo(source, { universe: name } = {}) {
+  const universe = universeArg(source.mapping, name);
+  const entry = source.mapping.universes[universe];
+  const hybrid = entry.kind === 'hybrid';
+  return checked({
+    commit: source.commit, universe, name: entry.name, kind: entry.kind ?? 'universe',
+    books: entry.books, playground: entry.playground, types: source.mapping.types, manuscript: source.mapping.manuscript,
+    ...(hybrid ? {
+      sources: entry.sources, constraints: entry.constraints,
+      ...(entry.notes === undefined ? {} : { notes: entry.notes }),
+    } : {}),
+  });
+}

packages/library/tests/index-build.test.mjs

@@ -0,0 +1,92 @@
+// Index tests (C2-05a): the cache key and its bound, failed reads, mapped-only contents, and the rebuild
+// time on a 3,000-file fixture. Fixtures are made up and built under the scratch area.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { mkdirSync, symlinkSync, writeFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { performance } from 'node:perf_hooks';
+import { clearIndexCache, indexCacheSize, indexFor } from '../src/index-build.mjs';
+import { git, mapping, MARKER } from './helpers.mjs';
+import { note, scratchRepo } from './query-fixture.mjs';
+
+const FILES = {
+  'Book One/Characters/Mara Vell.md': note('character', 'Mara Vell', MARKER),
+  'Book One/Chapters/Chapter 01.md': '# One\n[[Mara Vell]]\n',
+  'Inbox Note.md': `${MARKER}\n`,
+};
+
+// A mapping whose harbor universe has the given display name. Each name gives a new cache key.
+const named = name => mapping(e => ({ ...e, universes: { ...e.universes, harbor: { ...e.universes.harbor, name } } }));
+
+test('the same commit, repo path and mapping return the same index, and only mapped files are in it', async t => {
+  clearIndexCache();
+  const { repo, commit } = scratchRepo(t, FILES);
+  const a = await indexFor({ repo, commit, mapping: mapping() });
+  const b = await indexFor({ repo, commit, mapping: mapping() });
+  assert.equal(a, b);
+  assert.equal(indexCacheSize(), 1);
+  assert.equal(a.commit, commit);
+  assert.ok(a.files.has('Book One/Characters/Mara Vell.md'));
+  assert.ok(!a.files.has('Inbox Note.md'));
+  assert.deepEqual(a.names.get('mara vell'), ['Book One/Characters/Mara Vell.md']);
+  assert.deepEqual(a.linksIn.get('Book One/Characters/Mara Vell.md').map(l => l.path), ['Book One/Chapters/Chapter 01.md']);
+});
+
+test('a different repo path, mapping or commit gets its own index', async t => {
+  clearIndexCache();
+  const { root, repo, commit } = scratchRepo(t, FILES);
+  const base = await indexFor({ repo, commit, mapping: mapping() });
+  const alias = join(root, 'alias');
+  symlinkSync(repo, alias);
+  assert.notEqual(await indexFor({ repo: alias, commit, mapping: mapping() }), base);
+  assert.notEqual(await indexFor({ repo, commit, mapping: named('Renamed Harbor') }), base);
+  mkdirSync(join(repo, 'Book One/Places'), { recursive: true });
+  writeFileSync(join(repo, 'Book One/Places/New.md'), note('place', 'New'));
+  git(repo, 'add', '-A');
+  git(repo, 'commit', '-qm', 'second');
+  const next = git(repo, 'rev-parse', 'HEAD');
+  const later = await indexFor({ repo, commit: next, mapping: mapping() });
+  assert.notEqual(later, base);
+  assert.equal(later.commit, next);
+  assert.ok(later.files.has('Book One/Places/New.md'));
+});
+
+test('the cache holds at most eight indexes and evicts the least recently used', async t => {
+  clearIndexCache();
+  const { repo, commit } = scratchRepo(t, FILES);
+  const maps = Array.from({ length: 9 }, (_, i) => named(`Harbor ${i}`));
+  const first = await indexFor({ repo, commit, mapping: maps[0] });
+  for (const m of maps.slice(1)) await indexFor({ repo, commit, mapping: m });
+  assert.equal(indexCacheSize(), 8);
+  assert.notEqual(await indexFor({ repo, commit, mapping: maps[0] }), first);
+  assert.equal(indexCacheSize(), 8);
+});
+
+test('a failed read is not kept in the cache', async t => {
+  clearIndexCache();
+  const { repo } = scratchRepo(t, FILES);
+  await assert.rejects(indexFor({ repo, commit: '0'.repeat(40), mapping: mapping() }));
+  assert.equal(indexCacheSize(), 0);
+});
+
+test('a missing or unchecked mapping is refused before any read', async t => {
+  clearIndexCache();
+  const { repo, commit } = scratchRepo(t, FILES);
+  await assert.rejects(indexFor({ repo, commit, mapping: undefined }), { code: 'library-mapping-invalid' });
+  await assert.rejects(indexFor({ repo, commit, mapping: { kind: 'hybrid' } }), { code: 'library-mapping-invalid' });
+});
+
+test('a 3,000-file rebuild completes and its time is reported', { timeout: 300_000 }, async t => {
+  clearIndexCache();
+  const folders = ['Characters', 'Places', 'Research'];
+  const files = {};
+  for (let i = 0; i < 3000; i++) {
+    files[`Book One/${folders[i % 3]}/Note ${i}.md`] = note('character', `Note ${i}`, `Body ${i} [[Note ${(i + 1) % 3000}]]`);
+  }
+  const { repo, commit } = scratchRepo(t, files);
+  const started = performance.now();
+  const index = await indexFor({ repo, commit, mapping: mapping() });
+  const ms = performance.now() - started;
+  t.diagnostic(`3,000-file index rebuild: ${ms.toFixed(0)} ms`);
+  assert.equal(index.paths.length, 3000);
+});

packages/library/tests/query-fixture.mjs

@@ -0,0 +1,31 @@
+// Scratch repos for the query and index tests (C2-05a). They are built under tmpdir(), as helpers.mjs
+// repo() does; the gate sets TMPDIR under /mnt/storage/scratch/tmp, never /tmp (RULINGS "tmpdir flag").
+// Bodies are made up.
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { dirname, join } from 'node:path';
+import { git } from './helpers.mjs';
+
+// A repo with one commit holding `files` (path -> text). Removed when the test ends.
+export function scratchRepo(t, files) {
+  const root = mkdtempSync(join(tmpdir(), 'r216-'));
+  t.after(() => rmSync(root, { recursive: true, force: true }));
+  const repo = join(root, 'books');
+  mkdirSync(repo);
+  git(repo, 'init', '-q', '-b', 'main');
+  for (const [path, text] of Object.entries(files)) {
+    mkdirSync(dirname(join(repo, path)), { recursive: true });
+    writeFileSync(join(repo, path), text);
+  }
+  git(repo, 'add', '-A');
+  git(repo, 'commit', '-qm', 'fixture');
+  return { root, repo, commit: git(repo, 'rev-parse', 'HEAD') };
+}
+
+// A note: front matter with a type and a name, optional extra front matter lines, then a body.
+export const note = (type, name, body = '', extra = []) => ['---', `type: ${type}`, `name: ${name}`, ...extra, '---', body, ''].join('\n');
+
+// The one exclusion the hybrid tests use, and the paths it hides. C2-15 (row 267) replaces the reading of
+// `exclude` (a path prefix today); swapping these two constants is the whole change to the tests.
+export const EXCLUSION = { exclude: 'Book One/Research' };
+export const EXCLUDED_PATHS = ['Book One/Research/Ferry Logs.md'];

packages/library/tests/query.test.mjs

@@ -0,0 +1,369 @@
+// Query tests for design 3 (C2-05a): universe isolation, scope labels, unmapped files, hybrids, paging
+// under the reply cap, refusals and manuscript paging. Fixtures are made up and built under the scratch area.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { REPLY_CAP } from '../../harness/src/tools.mjs';
+import { find, get, search, manuscript, universeInfo, QUERY_REPLY_CAP, LOOKUP_LIMIT, MANUSCRIPT_LINES } from '../src/query.mjs';
+import { mapping, MARKER } from './helpers.mjs';
+import { scratchRepo, note, EXCLUSION, EXCLUDED_PATHS } from './query-fixture.mjs';
+
+// A hybrid over harbor and second. Its one constraint is EXCLUSION (query-fixture.mjs) and it declares no
+// books or playground.
+const WITH_BLEND = e => ({
+  ...e,
+  universes: {
+    ...e.universes,
+    blend: {
+      kind: 'hybrid', name: 'Blend', sources: ['harbor', 'second'], books: [], playground: [],
+      constraints: [EXCLUSION], notes: 'made-up hybrid',
+    },
+  },
+});
+
+// PRD 1.14 levels (C2-01c): harbor gets a universe-level playground prefix outside every book, and a draft
+// universe has only playground prefixes. Files there have book null.
+const WITH_LEVELS = e => ({
+  ...WITH_BLEND(e),
+  universes: {
+    ...WITH_BLEND(e).universes,
+    harbor: { ...e.universes.harbor, playground: ['Book One/Playground/', 'Notes/Harbor/'] },
+    idea: { kind: 'draft', name: 'New World', playground: ['Drafts/New World/'] },
+  },
+});
+const LEVEL_FILES = {
+  'Notes/Harbor/Scraps.md': note('summary', 'Scraps', `${MARKER} loose`),
+  'Notes/Harbor/Chapters/Idea Chapter.md': `# Idea\n${MARKER} unbooked chapter\n`,
+  'Drafts/New World/Characters/Rin.md': note('character', 'Rin', `${MARKER} draft`),
+  'Drafts/New World/Summary.md': note('summary', 'Summary', `${MARKER} draft`),
+};
+
+const FILES = {
+  'Book One/Characters/Mara Vell.md': note('character', 'Mara Vell', `Grey eyes. ${MARKER}`,
+    ['appears_in: "[[Book One/Chapters/Chapter 01]]"', 'relationships:', '  - "[[Tomas]]"']),
+  'Book One/Characters/Tomas.md': note('character', 'Tomas', MARKER),
+  'Book One/Chapters/Chapter 01.md': `# One\n${MARKER} [[Mara Vell]] met [[Book One/Places/Harbor Town|the harbor]].\n`,
+  'Book One/Chapters/Chapter 02.md': 'Quiet. [[Ferry Logs]] [[Ilse]]\n',
+  'Book One/Places/Harbor Town.md': note('place', 'Harbor Town', `Salt. ${MARKER}`),
+  'Book One/Research/Ferry Logs.md': note('research', 'Ferry Logs', `Timetable. ${MARKER}`),
+  'Book One/Playground/What If.md': note('summary', 'What If', `${MARKER} [[Mara Vell]]`),
+  'Second World/Characters/Ilse.md': note('character', 'Ilse', `${MARKER} Ilse.`),
+  'Second World/Chapters/01.md': '# Elsewhere\n[[Ilse]] waits.\n',
+  'Inbox Note.md': `${MARKER}\n`,
+  'Book One/Board.canvas': '{"nodes":[]}\n',
+};
+
+const src = (ref, map = mapping()) => ({ repo: ref.repo, commit: ref.commit, mapping: map });
+const paths = reply => reply.results.map(r => r.path);
+
+test('the query reply cap equals the harness reply cap', () => {
+  assert.equal(QUERY_REPLY_CAP, REPLY_CAP);
+});
+
+test('find is bound to its universe and refuses a call without one', async t => {
+  const s = src(scratchRepo(t, FILES));
+  const names = paths(await find(s, { universe: 'harbor', query: '' }));
+  assert.ok(names.length > 0);
+  assert.ok(names.every(p => p.startsWith('Book One/')));
+  assert.ok(!names.includes('Second World/Characters/Ilse.md'));
+  await assert.rejects(find(s, { query: '' }), { code: 'query-argument-invalid' });
+  await assert.rejects(find(s, { universe: 'nowhere', query: '' }), { code: 'query-universe-unknown' });
+});
+
+test('every result carries its scope, and playground appears only when asked for', async t => {
+  const s = src(scratchRepo(t, FILES));
+  const canon = (await find(s, { universe: 'harbor', query: '' })).results;
+  assert.ok(canon.every(r => r.scope === 'canon'));
+  assert.ok(!canon.some(r => r.path.includes('/Playground/')));
+  const play = (await find(s, { universe: 'harbor', query: '', scope: 'playground' })).results;
+  assert.deepEqual(play.map(r => r.path), ['Book One/Playground/What If.md']);
+  assert.ok(play.every(r => r.scope === 'playground'));
+});
+
+test('unmapped files never appear in any reply', async t => {
+  const s = src(scratchRepo(t, FILES));
+  assert.deepEqual((await find(s, { universe: 'harbor', query: 'Inbox' })).results, []);
+  assert.deepEqual((await find(s, { universe: 'harbor', query: 'Board' })).results, []);
+  const hits = (await search(s, { universe: 'harbor', text: MARKER })).results;
+  assert.ok(hits.length > 0);
+  assert.ok(hits.every(r => r.path !== 'Inbox Note.md' && r.path !== 'Book One/Board.canvas'));
+});
+
+test('a hybrid sees its sources canon, minus exclusions, and no playground', async t => {
+  const s = src(scratchRepo(t, FILES), mapping(WITH_BLEND));
+  const reply = await find(s, { universe: 'blend', query: '' });
+  assert.deepEqual(paths(reply).sort(), [
+    'Book One/Chapters/Chapter 01.md', 'Book One/Chapters/Chapter 02.md',
+    'Book One/Characters/Mara Vell.md', 'Book One/Characters/Tomas.md', 'Book One/Places/Harbor Town.md',
+    'Second World/Chapters/01.md', 'Second World/Characters/Ilse.md',
+  ]);
+  assert.ok(reply.results.every(r => r.scope === 'canon' && ['harbor', 'second'].includes(r.universe)));
+  assert.deepEqual((await find(s, { universe: 'blend', query: '', scope: 'playground' })).results, []);
+  assert.deepEqual((await find(s, { universe: 'blend', query: 'Ferry' })).results, []);
+});
+
+test('a hybrid gets a source file it can see, and not an excluded or foreign one', async t => {
+  const ref = scratchRepo(t, FILES);
+  const hybrid = src(ref, mapping(WITH_BLEND));
+  const ilse = await get(hybrid, { universe: 'blend', path: 'Second World/Characters/Ilse.md' });
+  assert.equal(ilse.scope, 'canon');
+  assert.ok(ilse.links_in.some(l => l.path === 'Second World/Chapters/01.md'));
+  assert.equal(await get(hybrid, { universe: 'blend', path: 'Book One/Research/Ferry Logs.md' }), null);
+  assert.equal(await get(src(ref), { universe: 'harbor', path: 'Second World/Characters/Ilse.md' }), null);
+});
+
+test('get lists visible links both ways and drops a target another universe cannot see', async t => {
+  const ref = scratchRepo(t, FILES);
+  const harbor = src(ref);
+  const ch1 = await get(harbor, { universe: 'harbor', path: 'Book One/Chapters/Chapter 01.md' });
+  assert.ok(ch1.links_out.some(l => l.path === 'Book One/Characters/Mara Vell.md' && l.line === 2));
+  assert.ok(ch1.links_out.some(l => l.path === 'Book One/Places/Harbor Town.md'));
+  const ch2 = await get(harbor, { universe: 'harbor', path: 'Book One/Chapters/Chapter 02.md' });
+  assert.ok(ch2.links_out.some(l => l.path === 'Book One/Research/Ferry Logs.md'));
+  assert.ok(!ch2.links_out.some(l => l.path === 'Second World/Characters/Ilse.md'));
+  const mara = await get(harbor, { universe: 'harbor', path: 'Book One/Characters/Mara Vell.md' });
+  assert.ok(mara.links_in.some(l => l.path === 'Book One/Chapters/Chapter 01.md'));
+  assert.ok(mara.links_in.some(l => l.path === 'Book One/Playground/What If.md'));
+  assert.ok(mara.links_out.some(l => l.path === 'Book One/Characters/Tomas.md' && l.field === 'relationships'));
+  assert.ok(mara.links_out.some(l => l.path === 'Book One/Chapters/Chapter 01.md' && l.field === 'appears_in'));
+  const blendCh2 = await get(src(ref, mapping(WITH_BLEND)), { universe: 'blend', path: 'Book One/Chapters/Chapter 02.md' });
+  assert.ok(blendCh2.links_out.some(l => l.path === 'Second World/Characters/Ilse.md'));
+});
+
+test('a long list pages by position, never cuts an item, and returns 50 per page', async t => {
+  const files = { ...FILES };
+  for (let i = 1; i <= 120; i++) files[`Book One/Places/Note ${i}.md`] = note('place', `Note ${i}`);
+  const s = src(scratchRepo(t, files));
+  const seen = [];
+  let offset = 0;
+  for (let pages = 0; pages < 10; pages++) {
+    const reply = await find(s, { universe: 'harbor', query: 'Note', offset });
+    assert.ok(JSON.stringify(reply).length <= QUERY_REPLY_CAP);
+    assert.ok(reply.results.length <= LOOKUP_LIMIT);
+    if (pages === 0) assert.equal(reply.results.length, LOOKUP_LIMIT);
+    seen.push(...paths(reply));
+    if (reply.next === null) break;
+    offset = reply.next;
+  }
+  assert.equal(seen.length, 120);
+  assert.equal(new Set(seen).size, 120);
+});
+
+test('a page stays under the reply cap when items are large', async t => {
+  const big = 'x'.repeat(2000);
+  const files = { ...FILES };
+  for (let i = 1; i <= 40; i++) files[`Book One/Places/Big ${i}.md`] = note('place', `Big ${i}`, '', [`appears_in: "${big}"`]);
+  const s = src(scratchRepo(t, files));
+  const first = await find(s, { universe: 'harbor', query: 'Big' });
+  assert.ok(JSON.stringify(first).length <= QUERY_REPLY_CAP);
+  assert.ok(first.results.length > 0 && first.results.length < 40);
+  assert.notEqual(first.next, null);
+  const seen = [];
+  let offset = 0;
+  for (let pages = 0; pages < 10; pages++) {
+    const reply = await find(s, { universe: 'harbor', query: 'Big', offset });
+    assert.ok(JSON.stringify(reply).length <= QUERY_REPLY_CAP);
+    seen.push(...paths(reply));
+    if (reply.next === null) break;
+    offset = reply.next;
+  }
+  assert.equal(new Set(seen).size, 40);
+});
+
+test('a search line too long to fit alone comes back marked, with no excerpt, and the other hits still return', async t => {
+  const huge = 'y'.repeat(QUERY_REPLY_CAP + 1000);
+  const s = src(scratchRepo(t, { ...FILES, 'Book One/Places/Wall.md': note('place', 'Wall', `${huge} ${MARKER}`) }));
+  const reply = await search(s, { universe: 'harbor', text: 'yyyyyyyy' });
+  assert.deepEqual(reply.results, [{ path: 'Book One/Places/Wall.md', line: 5, excerpt: null, excerpt_too_long: true, scope: 'canon' }]);
+  const mixed = await search(s, { universe: 'harbor', text: MARKER.toLowerCase() });
+  assert.ok(mixed.results.some(r => r.excerpt_too_long === true));
+  assert.ok(mixed.results.some(r => typeof r.excerpt === 'string' && !('excerpt_too_long' in r)));
+  assert.ok(JSON.stringify(mixed).length <= QUERY_REPLY_CAP);
+});
+
+test('a find item that cannot fit alone is refused, not cut', async t => {
+  const huge = 'y'.repeat(QUERY_REPLY_CAP + 1000);
+  const s = src(scratchRepo(t, { ...FILES, 'Book One/Places/Wall.md': note('place', 'Wall', '', [`appears_in: "${huge}"`]) }));
+  await assert.rejects(find(s, { universe: 'harbor', query: 'Wall' }), { code: 'query-item-too-large' });
+});
+
+test('get pages its lines, and the next line picks up where the page stopped', async t => {
+  const body = `${Array.from({ length: 500 }, (_, i) => `Line ${i + 1} ${'z'.repeat(120)}`).join('\n')}\n`;
+  const s = src(scratchRepo(t, { ...FILES, 'Book One/Chapters/Long.md': body }));
+  const first = await get(s, { universe: 'harbor', path: 'Book One/Chapters/Long.md' });
+  assert.equal(first.lines[0][0], 1);
+  assert.ok(first.lines.length < 501);
+  assert.notEqual(first.next, null);
+  let from = 1, count = 0;
+  for (let pages = 0; pages < 10; pages++) {
+    const page = await get(s, { universe: 'harbor', path: 'Book One/Chapters/Long.md', from });
+    count += page.lines.length;
+    if (page.next === null) break;
+    from = page.next;
+  }
+  assert.equal(count, 501);
+});
+
+test('get refuses a file whose front matter alone is over the cap, and a line alone is over the cap', async t => {
+  const huge = 'q'.repeat(QUERY_REPLY_CAP + 1000);
+  const s = src(scratchRepo(t, {
+    ...FILES,
+    'Book One/Places/Heavy.md': note('place', 'Heavy', '', [`appears_in: "${huge}"`]),
+    'Book One/Chapters/Wide.md': `${huge}\n`,
+  }));
+  await assert.rejects(get(s, { universe: 'harbor', path: 'Book One/Places/Heavy.md' }), { code: 'query-item-too-large' });
+  await assert.rejects(get(s, { universe: 'harbor', path: 'Book One/Chapters/Wide.md' }), { code: 'query-item-too-large' });
+});
+
+test('get pages the links of a hub note, every page carries the front matter, and the pages add up', async t => {
+  const files = { ...FILES };
+  for (let i = 1; i <= 900; i++) files[`Book One/Chapters/Mention ${i}.md`] = `[[Tomas]] ${'w'.repeat(60)}\n`;
+  const s = src(scratchRepo(t, files));
+  const seen = [];
+  const PAST_END = 1000;
+  let linksFrom = 0, pages = 0, lines = 0, from = 1;
+  for (; pages < 40; pages++) {
+    const page = await get(s, { universe: 'harbor', path: 'Book One/Characters/Tomas.md', from, links_from: linksFrom });
+    assert.ok(JSON.stringify(page).length <= QUERY_REPLY_CAP);
+    assert.equal(page.frontmatter.name, 'Tomas');
+    seen.push(...page.links_in.map(l => l.path));
+    if (from !== PAST_END) lines += page.lines.length;
+    // Once the lines are read, ask past the last one: the page then carries links alone.
+    from = page.next ?? PAST_END;
+    if (page.links_next === null && page.next === null) break;
+    if (page.links_next !== null) linksFrom = page.links_next;
+  }
+  assert.ok(pages > 1, 'the hub needed more than one page');
+  assert.ok(pages < 40);
+  assert.equal(seen.filter(p => p.startsWith('Book One/Chapters/Mention ')).length, 900);
+  assert.equal(new Set(seen).size, seen.length, 'no link comes back twice');
+  assert.equal(lines, 6, 'the five lines of the note and the empty one after its last newline');
+  const tail = await get(s, { universe: 'harbor', path: 'Book One/Characters/Tomas.md', from: PAST_END });
+  assert.deepEqual(tail.lines, []);
+  assert.equal(tail.next, null);
+});
+
+test('get rejects a bad links_from', async t => {
+  const s = src(scratchRepo(t, FILES));
+  await assert.rejects(get(s, { universe: 'harbor', path: 'Book One/Characters/Tomas.md', links_from: -1 }), { code: 'query-argument-invalid' });
+  const past = await get(s, { universe: 'harbor', path: 'Book One/Characters/Tomas.md', links_from: 99 });
+  assert.deepEqual([past.links_out, past.links_in, past.links_next], [[], [], null]);
+});
+
+test('search returns scoped line hits, case-insensitively, and refuses empty text', async t => {
+  const s = src(scratchRepo(t, FILES));
+  const reply = await search(s, { universe: 'harbor', text: 'marker' });
+  assert.ok(reply.results.length > 0);
+  assert.ok(reply.results.every(r => r.scope === 'canon' && r.path.startsWith('Book One/') && Number.isInteger(r.line)));
+  assert.ok(reply.results.some(r => r.path === 'Book One/Chapters/Chapter 01.md' && r.line === 2));
+  await assert.rejects(search(s, { universe: 'harbor', text: '' }), { code: 'query-argument-invalid' });
+});
+
+test('a manuscript call returns one chapter, at most 400 lines, and names its next line', async t => {
+  const long = `${Array.from({ length: 900 }, (_, i) => `Scene ${i + 1}`).join('\n')}\n`;
+  const s = src(scratchRepo(t, { ...FILES, 'Book One/Chapters/Long Chapter.md': long }));
+  const first = await manuscript(s, { universe: 'harbor', book: 'Book One', chapter: 'Long Chapter' });
+  assert.equal(first.lines.length, MANUSCRIPT_LINES);
+  assert.equal(first.next, MANUSCRIPT_LINES + 1);
+  const second = await manuscript(s, { universe: 'harbor', book: 'Book One', chapter: 'Long Chapter', from: first.next });
+  assert.equal(second.lines[0][0], MANUSCRIPT_LINES + 1);
+});
+
+test('a manuscript call without a chapter returns the first chapter in path order and names the next', async t => {
+  const s = src(scratchRepo(t, FILES));
+  const first = await manuscript(s, { universe: 'harbor', book: 'Book One' });
+  assert.equal(first.path, 'Book One/Chapters/Chapter 01.md');
+  assert.equal(first.next_chapter, 'Chapter 02');
+  const last = await manuscript(s, { universe: 'harbor', book: 'Book One', chapter: 'Chapter 02' });
+  assert.equal(last.path, 'Book One/Chapters/Chapter 02.md');
+  assert.equal(last.next_chapter, null);
+  assert.equal(await manuscript(s, { universe: 'harbor', book: 'Book One', chapter: 'Nope' }), null);
+});
+
+test('a chapter name that matches two visible files is refused', async t => {
+  const s = src(scratchRepo(t, { ...FILES, 'Book One/Chapters/Part/Chapter 01.md': 'Again.\n' }));
+  await assert.rejects(manuscript(s, { universe: 'harbor', book: 'Book One', chapter: 'Chapter 01' }), { code: 'query-chapter-ambiguous' });
+});
+
+test('a hybrid reads a source chapter through its declared sources only', async t => {
+  const ref = scratchRepo(t, FILES);
+  const hybrid = await manuscript(src(ref, mapping(WITH_BLEND)), { universe: 'blend', book: 'Second World', chapter: '01' });
+  assert.equal(hybrid.path, 'Second World/Chapters/01.md');
+  assert.equal(hybrid.scope, 'canon');
+  assert.equal(await manuscript(src(ref), { universe: 'harbor', book: 'Second World', chapter: '01' }), null);
+});
+
+test('universe info reports a hybrid sources, constraints and notes, and refuses an unknown universe', async t => {
+  const s = src(scratchRepo(t, FILES), mapping(WITH_BLEND));
+  const blend = await universeInfo(s, { universe: 'blend' });
+  assert.equal(blend.kind, 'hybrid');
+  assert.deepEqual(blend.sources, ['harbor', 'second']);
+  assert.deepEqual(blend.constraints, [EXCLUSION]);
+  assert.equal(blend.notes, 'made-up hybrid');
+  const harbor = await universeInfo(s, { universe: 'harbor' });
+  assert.equal(harbor.kind, 'universe');
+  assert.equal(harbor.sources, undefined);
+  await assert.rejects(universeInfo(s, { universe: 'ghost' }), { code: 'query-universe-unknown' });
+});
+
+test('an exclusion hides what it names from a hybrid and from nothing else', async t => {
+  const ref = scratchRepo(t, FILES);
+  const hybrid = src(ref, mapping(WITH_BLEND));
+  const seen = paths(await find(hybrid, { universe: 'blend', query: '' }));
+  for (const path of EXCLUDED_PATHS) assert.ok(!seen.includes(path), `${path} stays hidden`);
+  const own = paths(await find(src(ref), { universe: 'harbor', query: '' }));
+  for (const path of EXCLUDED_PATHS) assert.ok(own.includes(path), `${path} stays visible to its own universe`);
+});
+
+test('PRD 1.14: a lookup that names a book leaves book-null files out', async t => {
+  const s = src(scratchRepo(t, { ...FILES, ...LEVEL_FILES }), mapping(WITH_LEVELS));
+  const all = paths(await find(s, { universe: 'harbor', query: '', scope: 'playground' }));
+  assert.deepEqual(all.sort(), ['Book One/Playground/What If.md', 'Notes/Harbor/Chapters/Idea Chapter.md', 'Notes/Harbor/Scraps.md']);
+  const booked = await find(s, { universe: 'harbor', query: '', scope: 'playground', book: 'Book One' });
+  assert.deepEqual(paths(booked), ['Book One/Playground/What If.md']);
+  assert.ok(booked.results.every(r => r.book === 'Book One'));
+  const hits = (await search(s, { universe: 'harbor', text: 'unbooked', scope: 'playground' })).results;
+  assert.deepEqual(hits.map(r => r.path), ['Notes/Harbor/Chapters/Idea Chapter.md']);
+  assert.deepEqual((await search(s, { universe: 'harbor', text: 'unbooked', scope: 'playground', book: 'Book One' })).results, []);
+});
+
+test('PRD 1.14: library_manuscript never reads a book-null file', async t => {
+  const s = src(scratchRepo(t, { ...FILES, ...LEVEL_FILES }), mapping(WITH_LEVELS));
+  // The unbooked file sits under a manuscript folder, so it has type manuscript and book null.
+  const listed = await find(s, { universe: 'harbor', query: 'Idea', scope: 'playground' });
+  assert.deepEqual(listed.results.map(r => [r.path, r.type, r.book]), [['Notes/Harbor/Chapters/Idea Chapter.md', 'manuscript', null]]);
+  assert.equal(await manuscript(s, { universe: 'harbor', book: 'Book One', scope: 'playground', chapter: 'Idea Chapter' }), null);
+  assert.equal(await manuscript(s, { universe: 'harbor', book: 'Book One', scope: 'playground' }), null);
+  assert.equal(await manuscript(s, { universe: 'harbor', book: 'Notes', scope: 'playground', chapter: 'Idea Chapter' }), null);
+});
+
+test('PRD 1.14: a draft universe has no canon, so its lookups return files only with scope playground', async t => {
+  const s = src(scratchRepo(t, { ...FILES, ...LEVEL_FILES }), mapping(WITH_LEVELS));
+  assert.deepEqual((await find(s, { universe: 'idea', query: '' })).results, []);
+  assert.deepEqual((await search(s, { universe: 'idea', text: MARKER })).results, []);
+  const found = await find(s, { universe: 'idea', query: '', scope: 'playground' });
+  assert.deepEqual(paths(found).sort(), ['Drafts/New World/Characters/Rin.md', 'Drafts/New World/Summary.md']);
+  assert.ok(found.results.every(r => r.scope === 'playground' && r.universe === 'idea' && r.book === null));
+  const hits = (await search(s, { universe: 'idea', text: 'draft', scope: 'playground' })).results;
+  assert.equal(hits.length, 2);
+  const rin = await get(s, { universe: 'idea', path: 'Drafts/New World/Characters/Rin.md' });
+  assert.equal(rin.scope, 'playground');
+  assert.equal(await get(s, { universe: 'harbor', path: 'Drafts/New World/Characters/Rin.md' }), null);
+});
+
+test('PRD 1.14: library_universe on a draft returns its kind, name and prefixes', async t => {
+  const s = src(scratchRepo(t, { ...FILES, ...LEVEL_FILES }), mapping(WITH_LEVELS));
+  const draft = await universeInfo(s, { universe: 'idea' });
+  assert.equal(draft.kind, 'draft');
+  assert.equal(draft.name, 'New World');
+  assert.deepEqual(draft.playground, ['Drafts/New World/']);
+  assert.deepEqual(draft.books, []);
+  assert.equal(draft.sources, undefined);
+});
+
+test('a hybrid gets a source playground file as null, while the source gets it with scope playground', async t => {
+  const ref = scratchRepo(t, FILES);
+  const path = 'Book One/Playground/What If.md';
+  assert.equal(await get(src(ref, mapping(WITH_BLEND)), { universe: 'blend', path }), null);
+  const own = await get(src(ref), { universe: 'harbor', path });
+  assert.equal(own.scope, 'playground');
+});