fix(spec): deleted authorable-surface baseline lines must prove themselves (#4650)

Check (a) reads authorable-surface.json from the commit under check, so
hand-deleting a baseline line deleted the evidence it runs on (#4638,
#4643 landed exactly that way; #4662 proved the file was hand-edited).
gen:schema / check:authorable-surface now add check (c): every key
present at the merge base with origin/main but absent from this build
must carry one of three in-gate proofs —

  1. aged-out tombstone: base entry [RETIRED] + an ADR-0087
     conversion/migration registered >= 2 majors ago;
  2. def not reachable from the metadata-type roots (2026-08-02 ruling):
     BFS over the build's in-memory Zod graph from
     BUILTIN_METADATA_TYPE_SCHEMAS + EXTRA_METADATA_TYPE_SCHEMAS, with
     derived-clone bridging so .refine()/.extend() copies keep their
     originals protected; waives ONLY this file's tombstone requirement;
  3. whole def no longer emitted (manifest ratchet / api-surface
     jurisdiction).

Anchoring on the merge base (not HEAD) keeps the check alive in CI,
where HEAD is the PR's own commit and a HEAD-relative diff is always
empty. --check further rejects any byte of the file that is not the
generator's output (#4662 description drift class); write mode
regenerates it. Checks (a0)/(a)/(b) unchanged and pinned by tests.

Fixes #4650

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0176qgxgCXTJCUv4YFLtusP9

Author: claude

.changeset/authorable-surface-delete-proof.md

@@ -0,0 +1,36 @@
+---
+"@objectstack/spec": patch
+---
+
+fix(spec): deleted authorable-surface baseline lines must prove themselves (#4650)
+
+The authorable-surface ratchet's check (a) reads `authorable-surface.json` from
+the same commit it is checking, so hand-deleting a baseline line deleted the
+very evidence the check runs on — #4638 and #4643 both removed authorable keys
+with zero registered conversions and a green gate, and #4662 proved the file
+had been hand-edited. `gen:schema` (and `check:authorable-surface`) now anchor
+deletions on the baseline at the **merge base with `origin/main`** — the one
+version of the file a PR cannot rewrite (comparing against `HEAD:` would be
+vacuous in CI, where HEAD is the PR's own commit) — and every deleted line must
+carry one of three proofs, all computed inside the gate:
+
+1. **Aged-out tombstone** — the base entry was `[RETIRED]` and its surface is
+   registered in `CONVERSIONS_BY_MAJOR` / `MIGRATIONS_BY_MAJOR` at a major ≥ 2
+   behind the current one (the "~two majors" the file's description has always
+   promised, now enforced).
+2. **Not reachable from the metadata-type roots** (2026-08-02 ruling on #4650)
+   — BFS over the build's in-memory Zod graph from
+   `BUILTIN_METADATA_TYPE_SCHEMAS` + the `EXTRA_METADATA_TYPE_SCHEMAS` overlay,
+   with derived-clone bridging so `.refine()`/`.extend()` copies (e.g.
+   `ViewSchema` inside `ViewMetadataSchema`) keep their originals protected.
+   Over-collected entries (REST envelopes and other never-parsed defs) may be
+   deleted without a tombstone; the exception waives only this file's
+   requirement and is not a license to change the schema.
+3. **The whole def left the build** — adjudicated by the
+   `json-schema.manifest.json` ratchet (#2978) and `check:api-surface`.
+
+`--check` additionally rejects any byte of `authorable-surface.json` that is
+not the generator's own output (description/formatting hand-edits included,
+per #4662); write mode regenerates such drift. Checks (a0)/(a)/(b) are
+unchanged. Build-time gate only — no runtime export, schema shape, or
+generated artifact changes.

packages/spec/scripts/build-schemas-check-mode.test.ts

@@ -33,6 +33,13 @@
 // read-only inputs — `src/`, `node_modules/`, `package.json`. That keeps the
 // production code path byte-for-byte: no test-only seam is added to the gate,
 // because a seam is itself a place where the gate can differ from what CI runs.
+//
+// The sandbox is also a REAL git repository with a fabricated
+// `refs/remotes/origin/main`, because the authorable-surface deletion check
+// (#4650) anchors on the baseline at the merge base with origin/main — the one
+// version of the file a PR cannot rewrite. Fabricating the ref (rather than
+// injecting a base through some test-only env var) keeps that discipline: the
+// gate runs exactly the git resolution CI runs.
 
 import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import { spawnSync } from 'node:child_process';
@@ -42,6 +49,8 @@ import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 
 import { RENAMED_DEFS } from './lib/renamed-defs';
+import { CONVERSIONS_BY_MAJOR } from '../src/conversions/registry';
+import { MIGRATIONS_BY_MAJOR } from '../src/migrations/registry';
 
 const HERE = path.dirname(fileURLToPath(import.meta.url));
 const PKG = path.resolve(HERE, '..');
@@ -64,10 +73,26 @@ const PHANTOM_KEY = 'ui/ZzzNeverEmittedByAnyBuild';
 let sandbox: string;
 let script: string;
 let manifestPath: string;
+let surfacePath: string;
 let pristine: string;
+let pristineSurface: string;
+
+/** Run git in the sandbox repo; throws on failure so a broken fixture is loud. */
+function git(...args: string[]): string {
+  const r = spawnSync(
+    'git',
+    ['-c', 'user.name=build-schemas-test', '-c', 'user.email=test@example.invalid', ...args],
+    { cwd: sandbox, encoding: 'utf8' },
+  );
+  if (r.status !== 0) {
+    throw new Error(`git ${args.join(' ')} failed (${r.status}): ${r.stderr}`);
+  }
+  return (r.stdout ?? '').trim();
+}
 
 beforeAll(() => {
   pristine = fs.readFileSync(REAL_MANIFEST, 'utf8');
+  pristineSurface = fs.readFileSync(path.join(PKG, 'authorable-surface.json'), 'utf8');
   sandbox = fs.mkdtempSync(path.join(os.tmpdir(), 'build-schemas-check-'));
   fs.cpSync(path.join(PKG, 'scripts'), path.join(sandbox, 'scripts'), { recursive: true });
   for (const entry of ['src', 'node_modules', 'package.json']) {
@@ -81,6 +106,14 @@ beforeAll(() => {
   );
   script = path.join(sandbox, 'scripts', 'build-schemas.ts');
   manifestPath = path.join(sandbox, 'json-schema.manifest.json');
+  surfacePath = path.join(sandbox, 'authorable-surface.json');
+  // Anchor for the #4650 deletion check: a git repo whose origin/main holds the
+  // committed baseline. Only the baseline is tracked — src/node_modules stay
+  // symlinked, untracked reads the same as any dirty worktree.
+  git('init', '-q', '-b', 'main', '.');
+  git('add', 'authorable-surface.json');
+  git('commit', '-q', '-m', 'baseline: committed authorable-surface.json');
+  git('update-ref', 'refs/remotes/origin/main', 'HEAD');
 });
 
 afterAll(() => {
@@ -208,3 +241,275 @@ describe('build-schemas.ts --check — a check reports, it does not write (#4711
     },
   );
 });
+
+// ─────────────────────────────────────────────────────────────────────────────
+// #4650 — a deleted authorable-surface line must prove itself.
+//
+// Checks (a)/(b) read authorable-surface.json from the SAME commit, so deleting
+// a baseline line deleted the evidence they run on: #4638 and #4643 removed
+// authorable keys with zero registered conversions and a green gate. Check (c)
+// re-anchors deletions on the baseline at the merge base with origin/main — a
+// version the PR cannot rewrite — and demands one of three proofs: an aged-out
+// registered tombstone, unreachability from the metadata-type roots (2026-08-02
+// ruling), or the whole def leaving the build (the manifest ratchet's domain).
+//
+// Fixtures sabotage the BASE (extra lines committed under origin/main) while
+// the worktree file stays canonical: set-wise identical to the real attack
+// (line present at base, absent from the PR) without editing symlinked src/.
+// The live end-to-end shape — delete a prop from src AND its baseline line —
+// is exercised in the PR's recorded sabotage evidence instead.
+
+const readSurface = () => fs.readFileSync(surfacePath, 'utf8');
+
+/** Write a mutated baseline to the sandbox worktree; returns the exact bytes. */
+function seedSurface(mutate: (keys: string[]) => string[]): string {
+  const doc = JSON.parse(pristineSurface) as { description: string; keys: string[] };
+  doc.keys = mutate(doc.keys);
+  const text = JSON.stringify(doc, null, 2) + '\n';
+  fs.writeFileSync(surfacePath, text);
+  return text;
+}
+
+/** Commit a BASE variant of the baseline and point origin/main at it. */
+function seedBase(mutate: (keys: string[]) => string[]): string {
+  seedSurface(mutate);
+  git('add', 'authorable-surface.json');
+  git('commit', '-q', '--allow-empty', '-m', 'base variant');
+  const sha = git('rev-parse', 'HEAD');
+  git('update-ref', 'refs/remotes/origin/main', sha);
+  return sha;
+}
+
+/** Earliest ADR-0087 registration matching a surface leaf — the gate's clause
+ *  vocabulary (see check (b)/(c) in build-schemas.ts), reproduced here ONLY to
+ *  validate fixture choices loudly, never to assert gate behaviour. */
+function minRegisteredMajorForLeaf(leaf: string): number | null {
+  let min: number | null = null;
+  const consider = (surface: string, major: number): void => {
+    for (const clause of surface.split(' / ')) {
+      if (clause.endsWith('.' + leaf)) min = min === null ? major : Math.min(min, major);
+    }
+  };
+  for (const [major, list] of Object.entries(CONVERSIONS_BY_MAJOR)) {
+    for (const c of list) consider(c.surface, Number(major));
+  }
+  for (const [major, step] of Object.entries(MIGRATIONS_BY_MAJOR)) {
+    for (const sem of step.semantic ?? []) consider(sem.surface, Number(major));
+  }
+  return min;
+}
+
+const CURRENT_MAJOR = Number.parseInt(
+  (JSON.parse(fs.readFileSync(path.join(PKG, 'package.json'), 'utf8')) as { version: string })
+    .version,
+  10,
+);
+
+/** Reachable def (BUILTIN root `object`), never tombstoned — the #4643 shape. */
+const DELETED_LIVE = 'data/Object:zzNeverRetired4650';
+/** Reachable def, tombstoned at base but never registered in the ADR-0087 registries. */
+const DELETED_UNREGISTERED = 'data/Object:zzRetiredButUnregistered4650 [RETIRED]';
+/** Tombstoned AND registered, but too recently: `skill.triggerPhrases` was
+ *  registered at protocol 17. The guard below fails loudly once that ages out —
+ *  re-pick a clause registered within the last TOMBSTONE_AGE_MAJORS majors. */
+const DELETED_UNAGED_LEAF = 'triggerPhrases';
+const DELETED_UNAGED = `ai/Agent:${DELETED_UNAGED_LEAF} [RETIRED]`;
+/** Emitted but not reachable from any metadata-type root: a REST response
+ *  envelope no metadata document is ever parsed against (the issue's own
+ *  over-collection example). */
+const DELETED_UNREACHABLE = 'api/SessionResponse:zzOverCollected4650';
+/** Def the build no longer emits at all — the literal #4643 cluster. */
+const DELETED_GONE_DEF = ['identity/Session:userId', 'identity/Session:token'];
+/** Aged-out tombstone: `object.compactLayout` registered at protocol 11 —
+ *  ≥ 2 majors behind any current major, so this fixture never goes stale. */
+const DELETED_AGED_LEAF = 'compactLayout';
+const DELETED_AGED = `data/Object:${DELETED_AGED_LEAF} [RETIRED]`;
+/** Base key under a def RENAMED_DEFS moved: carried, so never a deletion. */
+const DELETED_BY_RENAME = 'integration/RateLimitConfig:maxRequests';
+
+describe('build-schemas.ts — deleted baseline lines must prove themselves (#4650)', () => {
+  beforeAll(() => {
+    // Fixture validity, asserted loudly instead of silently going stale.
+    const keys = (JSON.parse(pristineSurface) as { keys: string[] }).keys;
+    for (const injected of [
+      DELETED_LIVE,
+      DELETED_UNREGISTERED,
+      DELETED_UNAGED,
+      DELETED_UNREACHABLE,
+      ...DELETED_GONE_DEF,
+      DELETED_AGED,
+      DELETED_BY_RENAME,
+    ]) {
+      expect(
+        keys.includes(injected) || keys.includes(injected.replace(' [RETIRED]', '')),
+        `fixture ${injected} already exists in the committed baseline — pick another`,
+      ).toBe(false);
+    }
+    expect(
+      keys.some((k) => k.startsWith('identity/Session:')),
+      'identity/Session is emitted again — the vanished-def fixture needs a new def',
+    ).toBe(false);
+    const unagedMajor = minRegisteredMajorForLeaf(DELETED_UNAGED_LEAF);
+    expect(
+      unagedMajor !== null && CURRENT_MAJOR - unagedMajor < 2,
+      `'.${DELETED_UNAGED_LEAF}' (registered at major ${unagedMajor}) has aged out at major ` +
+        `${CURRENT_MAJOR} — re-pick a clause registered within the last 2 majors`,
+    ).toBe(true);
+    const agedMajor = minRegisteredMajorForLeaf(DELETED_AGED_LEAF);
+    expect(
+      agedMajor !== null && CURRENT_MAJOR - agedMajor >= 2,
+      `'.${DELETED_AGED_LEAF}' is no longer an aged-out registration`,
+    ).toBe(true);
+    // The manifest ratchet runs first; keep it current so every run reaches (c).
+    seedManifest((s) => s);
+  });
+
+  it(
+    'fails on deletions of reachable keys — live, unregistered, and not-yet-aged tombstones each say why',
+    { timeout: SPAWN_TIMEOUT_MS },
+    () => {
+      seedBase((s) => [...s, DELETED_LIVE, DELETED_UNREGISTERED, DELETED_UNAGED].sort());
+      const canonical = seedSurface((s) => s);
+
+      const { status, output } = run(['--check']);
+
+      expect(status).toBe(1);
+      expect(output).toContain('authorable baseline line(s) were deleted without proof (#4650)');
+      expect(output).toMatch(/data\/Object:zzNeverRetired4650 — def reachable .* LIVE \(never tombstoned\)/);
+      expect(output).toMatch(/data\/Object:zzRetiredButUnregistered4650 — .*tombstoned, but no conversion\/migration clause/);
+      expect(output).toMatch(new RegExp(`ai/Agent:${DELETED_UNAGED_LEAF} — .*registered at major \\d+`));
+      expect(output).toMatch(/must age ≥ 2 majors/);
+      // The remedy names the retirement route, not a hand-edit.
+      expect(output).toContain('gen:schema');
+      expect(readSurface()).toBe(canonical);
+    },
+  );
+
+  it(
+    'still fails after the deletion is COMMITTED (the CI shape): the anchor is the merge base with origin/main, not HEAD',
+    { timeout: SPAWN_TIMEOUT_MS * 2 },
+    () => {
+      seedBase((s) => [...s, DELETED_LIVE].sort());
+      const canonical = seedSurface((s) => s);
+      // Commit the sabotaged (canonical-minus-line, relative to base) file so
+      // the worktree is CLEAN — the state CI checks out. A `git show HEAD:`
+      // anchor would now compare the commit to itself and never fire.
+      git('add', 'authorable-surface.json');
+      git('commit', '-q', '-m', 'PR commit deleting a baseline line');
+
+      const check = run(['--check']);
+      expect(check.status).toBe(1);
+      expect(check.output).toContain('deleted without proof (#4650)');
+      expect(check.output).toContain(DELETED_LIVE);
+
+      // Write mode (gen:schema) must refuse identically — regeneration cannot
+      // bless a deletion either.
+      const write = run([]);
+      expect(write.status).toBe(1);
+      expect(write.output).toContain('deleted without proof (#4650)');
+      expect(readSurface()).toBe(canonical);
+    },
+  );
+
+  it(
+    'allows deletions that carry their own proof: unreachable def, vanished def, aged-out tombstone — each with its reason printed',
+    { timeout: SPAWN_TIMEOUT_MS },
+    () => {
+      seedBase((s) => [...s, DELETED_UNREACHABLE, ...DELETED_GONE_DEF, DELETED_AGED].sort());
+      const canonical = seedSurface((s) => s);
+
+      const { status, output } = run(['--check']);
+
+      expect(output).toContain('baseline deletion(s) since');
+      expect(output).toContain('carry their own proof (#4650)');
+      // Narrow exception (2026-08-02 ruling): computed in-gate from the real
+      // Zod graph, waiving ONLY the tombstone requirement.
+      expect(output).toMatch(/api\/SessionResponse:zzOverCollected4650 — def not reachable from the \d+ metadata-type roots/);
+      expect(output).toContain('BUILTIN_METADATA_TYPE_SCHEMAS + EXTRA_METADATA_TYPE_SCHEMAS');
+      expect(output).toContain('not a license to change the schema');
+      // Whole-def removal is the manifest ratchet's jurisdiction.
+      expect(output).toContain('identity/Session:* (2 line(s))');
+      expect(output).toContain('json-schema.manifest.json (#2978)');
+      // Aged-out tombstone names its registration major.
+      expect(output).toMatch(/data\/Object:compactLayout — \[RETIRED\] at [0-9a-f]+ and registered at major 11/);
+      expect(output).toContain('tombstone aged out');
+      expect(readSurface()).toBe(canonical);
+      expect(status).toBe(0);
+    },
+  );
+
+  it(
+    'check (a) is intact: a key the BUILD stops emitting while still recorded is fatal before (c) ever runs',
+    { timeout: SPAWN_TIMEOUT_MS },
+    () => {
+      const phantom = 'data/Object:zzPhantom4650';
+      seedBase((s) => [...s, phantom].sort());
+      const withPhantom = seedSurface((s) => [...s, phantom].sort());
+
+      const { status, output } = run(['--check']);
+
+      expect(status).toBe(1);
+      expect(output).toMatch(/1 authorable key\(s\) disappeared from the contract/);
+      expect(output).toContain(phantom);
+      expect(output).not.toContain('deleted without proof');
+      expect(readSurface()).toBe(withPhantom);
+    },
+  );
+
+  it(
+    'fails --check on a hand-edit that changes no key (generated-form mismatch, #4662), and write mode regenerates it',
+    { timeout: SPAWN_TIMEOUT_MS * 2 },
+    () => {
+      seedBase((s) => s);
+      const handEdited = seedSurface((s) => s).replace(
+        'Ratchet of every AUTHORABLE key',
+        'Ratchet  of every AUTHORABLE key',
+      );
+      fs.writeFileSync(surfacePath, handEdited);
+
+      const check = run(['--check']);
+      expect(check.status).toBe(1);
+      expect(check.output).toContain('does not match its generated form');
+      expect(readSurface()).toBe(handEdited);
+
+      const write = run([]);
+      expect(write.status).toBe(0);
+      expect(write.output).toContain('🔑 authorable-surface.json updated');
+      expect(readSurface()).toBe(pristineSurface);
+    },
+  );
+
+  it(
+    'fails LOUDLY when origin/main cannot be resolved — a deletion check that silently skips is the bypass again',
+    { timeout: SPAWN_TIMEOUT_MS },
+    () => {
+      seedBase((s) => s);
+      seedSurface((s) => s);
+      git('update-ref', '-d', 'refs/remotes/origin/main');
+      try {
+        const { status, output } = run(['--check']);
+        expect(status).toBe(1);
+        expect(output).toContain('Cannot resolve origin/main');
+        expect(output).toContain('#4650');
+      } finally {
+        git('update-ref', 'refs/remotes/origin/main', 'HEAD');
+      }
+    },
+  );
+
+  it(
+    'a declared def rename is not a deletion: base keys are carried through RENAMED_DEFS before comparing',
+    { timeout: SPAWN_TIMEOUT_MS },
+    () => {
+      expect(Object.keys(RENAMED_DEFS)).toContain('integration/RateLimitConfig');
+      seedBase((s) => [...s, DELETED_BY_RENAME].sort());
+      seedSurface((s) => s);
+
+      const { status, output } = run(['--check']);
+
+      expect(output).not.toContain('deleted without proof');
+      expect(output).not.toContain('carry their own proof');
+      expect(status).toBe(0);
+    },
+  );
+});