diff --git a/agents/morgana/work/queue-193a/BUILD.md b/agents/morgana/work/queue-193a/BUILD.md
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+# Row 193a build: the viewer level on R1's access file
+
+Morgana (Opus 5.5), 2026-10-20. Gitea #1691, parent row 193, design `agents/morgana/work/queue-193/DESIGN.md`
+r5 (e2d161e2e on morgana/row193, approved at r4 by Duckworth, duckworth-0014). Go: sage-1373 item 3. Base:
+`refactor` at aa1bd209e. Lands after FED R1 and is rebased onto R1's landing.
+
+## What it is
+
+Design 4.2: R1 refuses any grant level but `collaborator`. Row 193a widens that check to `collaborator` or
+`viewer` and refuses anything else. `covers` needs no change: FED 3.5 already compares the grant's level
+with the one asked for, so a viewer grant matches `{}` and `{level: 'viewer'}`, and fails
+`{level: 'collaborator'}`.
+
+## Why the candidate holds only a test now
+
+R1 (`packages/business/src/access.mjs`) has no candidate yet. Sage ruled no stub on refactor (sage-1373
+item 3). So this branch carries:
+
+- `packages/business/tests/access-levels.test.mjs`: the row 193a tests, written against R1's interface as
+  FED r4.5 (acd5f1f42) sections 3.5 and 7 give it.
+- The source change, below, to apply on R1's candidate at rebase.
+
+Until R1 lands, the test file fails with `ERR_MODULE_NOT_FOUND` for `../src/access.mjs`. That is expected.
+
+## The source change for the rebase
+
+In R1's level check, the allowed set becomes `["collaborator", "viewer"]`. It is one line wherever R1 keeps
+the level rule. Its refusal message must name the key path `grants[<i>].level`, as R1's own rule does.
+
+## Interface assumptions (to confirm against R1)
+
+FED r4.5 names `covers(grant, {business, project, instance}, now, {level})` exactly. It doesn't name the
+loader or validator export, or the shape of the context argument. The test assumes:
+
+- a pure validator `checkAccess(doc, {providers, peers, businesses})` that throws a `BusinessError`
+  (exit 2) naming the key path, as `checkVars` does;
+- `businesses` maps a business id to `{human, instances}`, because the rules need each business's
+  `human` and its declared instances.
+
+Every call into the validator goes through one `check()` helper at the top of the test file, so a different
+name or shape changes one place at rebase. The `covers` calls follow FED exactly.
+
+One test case R1 may not cover itself: a grant with no `level` refuses (`undefined` in the refused list).
+Design 4.2 says anything but the two levels refuses, and a missing level is not one of them.
+
+## Evidence
+
+Run on 2026-10-20 in the row193a worktree with `node --test --test-reporter=tap
+tests/access-levels.test.mjs` from `packages/business`.
+
+- Base (no access.mjs): fails to load, `ERR_MODULE_NOT_FOUND`.
+- Throwaway reference: an `access.mjs` with only the level rule, a declared-business rule and FED's
+  `covers`, placed in `src/`, run, then deleted, never committed. Result: pass 4, fail 0.
+
+Mutants on that reference, each failing exactly one test:
+
+| Mutant | Failing test |
+|---|---|
+| levels back to collaborator only | 1, "a grant's level is collaborator or viewer" |
+| `owner` added to the levels | 2, "any other level refuses with the key path named" |
+| `covers` ignores the asked level | 3, "covers tells a viewer grant from a collaborator grant" |
+| `covers` passes any grant when collaborator is asked | 3 |
+
+At rebase, the same four mutants run again on R1's real code before the row goes to review.
diff --git a/packages/business/tests/access-levels.test.mjs b/packages/business/tests/access-levels.test.mjs
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index 000000000..24cde07b7
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+++ b/packages/business/tests/access-levels.test.mjs
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+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { BusinessError } from "../src/errors.mjs";
+import * as access from "../src/access.mjs";
+
+// Row 193a (#1691): the viewer level. R1 (federation design r4.5, section 7) owns access.mjs and its
+// tests; this file pins only what row 193 adds: a grant's level is collaborator or viewer, and covers()
+// tells the two apart. Every call into R1 goes through check() below, so a change to R1's loader
+// interface edits one place.
+const CONTEXT = {
+  providers: ["authentik"],
+  peers: ["factory"],
+  businesses: { "creative-hub": { human: "melanie", instances: ["researcher", "writer"] } },
+};
+const check = (doc) => access.checkAccess(doc, CONTEXT);
+
+const PROJECT = "0b6f4a52-6f1e-4c7a-9a0e-3f1d2c4b5a69";
+const NOW = new Date("2026-10-20T19:30:00Z");
+
+function file(level) {
+  const grant = { id: "g-1", user: "jason", business: "creative-hub", projects: ["*"], instances: ["researcher"] };
+  if (level !== undefined) grant.level = level;
+  return {
+    accessVersion: 1,
+    revision: 1,
+    users: [{ id: "jason", home: "local", subjects: [{ provider: "authentik", sub: "s-1" }] }],
+    grants: [grant],
+  };
+}
+
+function refuses(fn, pattern) {
+  assert.throws(fn, (error) => {
+    assert.ok(error instanceof BusinessError, `expected BusinessError, got ${error}`);
+    assert.equal(error.exitCode, 2);
+    assert.match(error.message, pattern);
+    return true;
+  });
+}
+
+test("a grant's level is collaborator or viewer", () => {
+  for (const level of ["collaborator", "viewer"]) {
+    assert.doesNotThrow(() => check(file(level)), level);
+  }
+});
+
+test("any other level refuses with the key path named", () => {
+  for (const level of ["owner", "admin", "member", "Viewer", "viewer ", "", null, 1, ["viewer"], undefined]) {
+    refuses(() => check(file(level)), /grants\[0\]\.level/);
+  }
+});
+
+test("covers tells a viewer grant from a collaborator grant", () => {
+  const target = { business: "creative-hub", project: PROJECT, instance: "researcher" };
+  const viewer = file("viewer").grants[0];
+  const collaborator = file("collaborator").grants[0];
+  // Share reads ask for any level (design 9); create, open, send and share ask for collaborator.
+  assert.equal(access.covers(viewer, target, NOW, {}), true);
+  assert.equal(access.covers(viewer, target, NOW, { level: "viewer" }), true);
+  assert.equal(access.covers(viewer, target, NOW, { level: "collaborator" }), false);
+  assert.equal(access.covers(collaborator, target, NOW, {}), true);
+  assert.equal(access.covers(collaborator, target, NOW, { level: "collaborator" }), true);
+  assert.equal(access.covers(collaborator, target, NOW, { level: "viewer" }), false);
+});
+
+test("a viewer grant still needs its business, project, instance and expiry to cover", () => {
+  const viewer = { ...file("viewer").grants[0], projects: [PROJECT], expires: "2026-10-21T00:00:00Z" };
+  const target = { business: "creative-hub", project: PROJECT, instance: "researcher" };
+  assert.equal(access.covers(viewer, target, NOW, {}), true);
+  assert.equal(access.covers(viewer, { ...target, business: "other" }, NOW, {}), false);
+  assert.equal(access.covers(viewer, { ...target, project: "7c1e2d3f-0a9b-4c8d-8e7f-6a5b4c3d2e1f" }, NOW, {}), false);
+  assert.equal(access.covers(viewer, { ...target, instance: "writer" }, NOW, {}), false);
+  assert.equal(access.covers(viewer, target, new Date("2026-10-21T00:00:01Z"), {}), false);
+});