launchpad: row 192 packet, mutant 23 equivalent and the guard kept (sage-1407)

webui: Q175 phase 1 round 2, absolute post-sign-in Location checked on publicOrigin (row 192, #1690 )
webby-0019 B1, sage-1403: returnURL builds the Location from publicOrigin plus the parsed pathname and search, checks the origin again and returns the href, so a dot-segment `//host` path stays on the Console. Test 14 covers Webby's three cases and asserts each Location's origin; mutant 22 restores the r1 returnPath (killed). N1 design blob cite, N2 listed under Deviations, N3 SIGN_IN_COOKIE comment.
2026-10-20 15:07:24 -05:00 · 2026-10-20 14:54:43 -05:00 · 2026-10-20 14:30:24 -05:00
22 changed files with 1812 additions and 59 deletions
@@ -0,0 +1,178 @@
+# Row 192: Q175 phase 1, the Console verifies sign-in itself (`--sso`)
+
+Launchpad, 2026-10-20. Author Launchpad, reviewer Webby, gate owner Sage. Issue #1690. Brief
+`docs/plans/2026-10-20_sso-phase1.md`. Design `agents/sage/work/q175-sso/DESIGN.md` (blob 9e3eadb15c80).
+Rulings sage-1340 (F1 to F6) and sage-1347 (F7, F8). Plan launchpad-0001.
+
+Base 53bb59462 (`base.txt`). Candidate: branch `launchpad/row192`, r1 83b32d8d8 and the round 2 commit on it.
+`candidate-manifest.sha256` lists the 18 changed code, test and doc paths; the packet files are not in it. Drift
+check at the r2 commit: `git log 53bb59462..origin/refactor` (origin/refactor ae3c36f24) touches none of the 18 paths.
+
+No request in any test goes to auth.diversecanvas.com, mosaic.woltje.com or 127.0.0.1:7332. Every provider
+is the fake OP in `tests/helpers/fake-oidc.mjs`: https on 127.0.0.1 with a throwaway self-signed certificate,
+and a fetch that refuses any other origin. The public Host in the tests is `console.example.test`, sent as a
+header to the test's own loopback listener. No test reads or writes `~/.mosaic-dev`, `~/.config/mosaic-dev`,
+`~/.mosaic`, a slot file outside its temp dir, or a live unit.
+
+## Files
+
+| Path | Change |
+| --- | --- |
+| `package.json`, `package-lock.json` | `oauth4webapi` 3.8.8, exact, at the root (design: the copy runs `npm ci` there). No other dependency. |
+| `scripts/mosaic-config.mjs` | Accepts an optional `console.sso` key and checks it with `checkConsole`. Without the key, output is byte-identical (F2). |
+| `scripts/test-config.sh` | Test 25: a good `console.sso` passes; each refusal class refuses. 31/31. |
+| `packages/webui/src/sso-config.mjs` (new) | `checkConsole`: shape, `publicOrigin`, 1 to 8 providers, issuer https with a trailing slash, slot names, `ALGS` (asymmetric only), 1 to 64 subjects. |
+| `packages/webui/src/sso.mjs` (new) | The relying party: `readSlot`, discovery and JWKS with retry, `/auth/login`, `/auth/callback`, `/auth/logout`, sessions, `health()`, `summary()`, `formTargets()`. |
+| `packages/webui/src/serve.mjs` | Under `sso`: public Host only on the human listener (F4), `/auth/*` routes, session check before every page and API route, CSP `form-action` adds the end-session origins, tester listener refusals (F8). |
+| `packages/webui/src/cli.mjs` | `--sso`, its refusals, slot reads, the start lines, `close()` on stop. |
+| `packages/webui/src/chat-http.mjs` | Under `--sso` the session check already ran, so the header-user check is skipped; the Origin check uses `publicOrigin`. |
+| `packages/webui/src/public/app.js`, `bus.js`, `index.html` | 401 `sign-in required` signs the page out with a link to `/auth/login?return=...` (design test 24, F1). The Sign out form shows only when `/api/config` says `sso` (F7). |
+| `scripts/webui-service.sh` | Passes `--sso` through; `--send` refusal text names `--sso`. |
+| `packages/webui/tests/service.test.mjs` | The `--send` refusal regex follows the new text. |
+| `packages/webui/README.md` | New section "Sign-in in the Console (Q175 phase 1, #1690)". |
+| `packages/webui/tests/helpers/fake-oidc.mjs` (new) | The fake OP. |
+| `packages/webui/tests/sso.test.mjs` (new) | 28 tests: three positives and design tests 1 to 23 (some split in parts). |
+| `packages/webui/tests/sso-browser.test.mjs` (new) | 2 tests: design test 24 with F1, and F7. |
+
+## Tests run (single files, this worktree, final tree)
+
+| File | Pass | Fail |
+| --- | --- | --- |
+| sso | 28 | 0 |
+| sso-browser | 2 | 0 |
+| pinned-copy | 10 | 0 |
+| serve | 4 | 0 |
+| preview | 11 | 0 |
+| proof | 4 | 0 |
+| proof-cli | 3 | 0 |
+| send | 13 | 0 |
+| service | 31 | 0 |
+| tester-listener | 10 | 0 |
+| tester-cli | 2 | 0 |
+| board-held | 3 | 0 |
+| send-browser | 2 | 0 |
+| docs-browser | 1 | 0 |
+| chat | 23 | 0 |
+| chat-browser | 11 | 0 |
+| bus-browser | 2 | 0 |
+| settings-write | 4 | 0 |
+| project-file | 10 | 0 |
+| instances | 5 | 0 |
+| routes | 5 | 0 |
+| `scripts/test-config.sh` | 31 | 0 |
+
+The first singles pass failed `pinned-copy` 1 of 10: `ERR_MODULE_NOT_FOUND: Cannot find package
+'oauth4webapi'` from a copy's `sso.mjs`. The test's fixture repo writes an empty package.json and lock, so the
+copy's `npm ci` installs nothing, and `sso.mjs` imported oauth4webapi at module load. `cli.mjs` imports
+`sso.mjs` on every start, so plain `serve` broke. Fix: `sso.mjs` loads oauth4webapi inside `createSso`
+(`oauth ??= await import('oauth4webapi')`). A Console without `--sso` never resolves the package. A real copy
+still has it from the root lock. Mutant 21 restores the static import and `pinned-copy` kills it. After the
+fix: pinned-copy, sso, sso-browser and serve rerun green (counts above).
+
+Not run by me (slot work, busy at the time): the full webui package suite, the cli suite, and
+`scripts/test-*.sh` other than test-config. `packages/cli/tests/stack-copy.test.mjs` and
+`stack-release.test.mjs` also build copies with an empty lock and are the ones to watch for the same
+failure. They need Sage's gate.
+
+## Mutants (`mutants.py`, run as `python3 mutants.py <tree> [N ...]`)
+
+Each mutant edits one source file, runs one test file filtered to one test name, and restores the file
+checked by sha256. Final run on the final tree: `/mnt/storage/scratch/launchpad-r192/mutants-final.log`.
+
+| # | Mutant | Test | Result |
+| --- | --- | --- | --- |
+| 1 | drop validateApplicationLevelSignature | sso 9 | KILLED |
+| 2 | wrap the signature call in a continuing try/catch | sso 9 | KILLED |
+| 3 | drop the subjects check | sso 10 | KILLED |
+| 4 | accept HS256 and none in ALGS | sso 11 start | KILLED |
+| 5 | take the provider from the query | sso 15 | KILLED |
+| 6 | tester listener reads sign-in cookies (F8) | sso 12 | KILLED |
+| 7 | tester listener takes Authorization (F8) | sso 12 | KILLED |
+| 8 | tester listener takes x-authentik-* (F8) | sso 12 | KILLED |
+| 9 | skip the login record delete | sso 7 | KILLED |
+| 10 | drop HttpOnly from the session cookie | sso 20 and 21 | KILLED |
+| 11 | refresh last-seen on every request | sso 13 idle | KILLED |
+| 12 | build redirect_uri from the request Host | sso 22 | KILLED |
+| 13 | serve the loopback read path under --sso (F4) | sso 22 | KILLED |
+| 14 | bus.js fetchRead ignores 401 sign-in required (F1) | sso-browser 1 | KILLED |
+| 15 | bus.js fetchApi ignores 401 sign-in required (F1) | sso-browser 1 | KILLED |
+| 16 | app.js getJSON ignores 401 sign-in required | sso-browser 1 | KILLED |
+| 17 | app.js api() ignores 401 sign-in required | sso-browser 1 | KILLED |
+| 18 | signInRequired takes any 401 | sso-browser 1 | KILLED |
+| 19 | Sign out shown without the sso condition (F7) | sso-browser 2 | KILLED |
+| 20 | CSP form-action without the end-session origins | sso 13 CSP | KILLED |
+| 21 | import oauth4webapi at module load | pinned-copy | KILLED |
+| 22 | restore the r1 relative returnPath (round 2, B1) | sso 14 | KILLED |
+| 23 | drop the second origin check (round 2, sage-1403) | sso 14 | SURVIVED, equivalent, guard kept (sage-1407) |
+
+Mutant 16 survived its first run: test 1 had no `getJSON` path. The History click on
+`/api/conversations` was added and it is now killed.
+
+## Deviations from the design
+
+- **F1 (sage-1340).** `bus.js` `fetchRead` and `fetchApi` apply the same 401 `sign-in required` rule as
+  `app.js`, even when `/api/config` has no `sso`. Tested in sso-browser 1, mutants 14 and 15.
+- **F7 (sage-1347).** A Sign out form (`POST /auth/logout`) in the command bar, hidden unless `/api/config`
+  says `sso`. Tested in sso-browser 2, mutant 19.
+
+- **Proof header on 7333 under `--sso` (webby-0019 N2).** `cli.mjs` passes `testerProofHeader: null` under
+  `--sso`, since `--sso` refuses the proof pair and there is no header name to refuse. A request to 7333 that
+  still carries the old proof header is not refused for it. It gains nothing: under `--sso` no listener
+  reads a proof header (`proof` is null in `startServer`). Left as is.
+
+## Assumptions and choices
+
+- **F8 (sage-1347).** Under `--sso` the tester listener refuses a request carrying `Authorization`, either
+  `__Host-mosaic` cookie or any `x-authentik-*` header, case-insensitive (Node lower-cases header names).
+  sso 12 sends one of each; mutants 6 to 8.
+- **oauth4webapi loads lazily** inside `createSso` (see the pinned-copy failure above).
+- **Client authentication** is `ClientSecretBasic`; the fake OP's token endpoint checks Basic auth.
+- **Caps**: 1 to 8 providers, 1 to 64 subjects per provider, 64 sessions, 32 pending logins. The 33rd login
+  drops the oldest record (sso 17).
+- **CSP**: under `--sso`, `form-action` adds each provider's end-session origin. Chrome applies
+  `form-action` to the redirect after the Sign out POST, so without it the logout stops at the Console.
+  Tested in sso 13 CSP, mutant 20. Without `--sso` the CSP string is unchanged.
+- **`--send` refusal text** in cli.mjs and webui-service.sh now ends "or --sso".
+- **Start lines**: one `Sign-in provider:` line per provider with id, issuer, subject count and state
+  (`ready`, `refused` or `unreachable`). No client id, secret or sub.
+- **Test 1** uses `console.example.test` as the public Host, not mosaic.woltje.com (no request goes there).
+- **Test 11 slot files**: the owner check is not tested; the test can't create a file owned by another uid
+  without privilege. Symlink, 0644, 0640 and a file under the repository are tested.
+- **Test 23** covers a provider down at start: the Console starts, `/auth/login` is 503, loopback `/healthz`
+  is 200 with `sso: { a: 'unreachable' }`, one `discovery-failed` line, and the retry makes sign-in work. An
+  HS-only discovery at start refuses the start (in test 23 and in test 11 start).
+- **Test 22**: a Host of bare `localhost` without a port is not in the table. It hits the older
+  `non-local Host refused` check before the sso check; a comment in the test says so.
+
+## Round 2 (webby-0019)
+
+- **B1, open redirect after sign-in.** `returnPath` took any URL on `publicOrigin`, and dot segments can
+  normalize to a pathname of `//evil.example`, which a browser reads as scheme-relative in a relative
+  Location. Fix per sage-1403: `returnURL` (renamed) builds an absolute URL, `publicOrigin + pathname +
+  search`, checks its origin again, and returns its href. Anything else is `publicOrigin/`. The callback's
+  Location is now always absolute on the Console. Test 14 asserts the exact Location and its origin for each
+  case. It adds Webby's three rows (`/.//evil.example`, `/x/..//evil.example`,
+  `https://console.example.test//evil.example`), each now `https://console.example.test//evil.example`, a path
+  on the Console. It also adds `/board/./x`, which lands on `/board/x`. The positive test expects
+  `https://console.example.test/board?x=1`.
+- **Mutant 22** restores the r1 relative `returnPath`; test 14 kills it.
+- **Mutant 23** drops the second origin check. It SURVIVES, and I read it as equivalent: `checkConsole`
+  holds `publicOrigin` to a bare https origin, and a parsed https pathname always starts with `/`, so
+  `publicOrigin + pathname` can't parse to another origin. Webby agrees (webby-0022). Sage's ruling
+  (sage-1407): the check stays as an unreachable guard, and 23 is listed here as equivalent. That is a packet
+  note, not a candidate change.
+- **N1.** The design cite is now blob 9e3eadb15c80 (`git rev-parse 83b32d8d8:agents/sage/work/q175-sso/DESIGN.md`).
+- **N2.** Listed under Deviations.
+- **N3.** `SIGN_IN_COOKIE` has its own comment, above the row 177 comment and `TESTER_CHAT_WRITE`.
+- **N4.** Row 200 (#1698) covers it: `stack-release.sh` refuses `config-console-key` before any stop when the
+  target's loader refuses the key, on activate and rollback.
+- **N5.** No change.
+
+Round 2 runs, this worktree, final tree: `sso.test.mjs` 28/28 (`/mnt/storage/scratch/launchpad-r192/sso-r2.log`);
+mutants 22 and 23 (`/mnt/storage/scratch/launchpad-r192/mutants-r2.log`).
+
+## Not done here
+
+- Row 200 (#1698, `stack-release.sh activate --sso`) is chained on this candidate and starts only after the
+  manifest is with Webby (sage-1369).
+- Full suites are for Sage's gate.
@@ -0,0 +1 @@
+53bb59462120a03a9f54b02881895e3f575e501c
@@ -0,0 +1,18 @@
+95d9a48812eebc415e3605239788e5b0746f1457a3bf0f9b9651a8c745e8b0f6  package.json
+390cbb0ef88de6cbc6d8f43b9e212abfdf0ef0e1c88fa02f5ab790caabc53eed  package-lock.json
+726b71bcfdb4d9409cefc86bed2fbe8e678c6efb50bcf5bb22344aeda1eee201  packages/webui/README.md
+f7b6b68906f13a644854b8083287dfa2936e8defc6207d05739e89763cc91440  packages/webui/src/chat-http.mjs
+4a2d226bdbfee98b180103f71b3cb8122303cfac4aeece42bd30ce167ba6ff55  packages/webui/src/cli.mjs
+41ee8798c34ee491b80ae1b42c3e96cd5d12fb1603b1ab88ac2dd10b5fb27964  packages/webui/src/public/app.js
+e6c8f838eb7cdc2ae556c04451ca4c8f2d433117a17f285a144cfc7dff03e2a4  packages/webui/src/public/bus.js
+f276fa440ec938638cb3e0f1b812fafa929460a6b96f1dab4cf1076a7c0c18ea  packages/webui/src/public/index.html
+333d474b1c7e753938aedc639c08f9db0e787faf56aa8068d013fd304a0b3b7e  packages/webui/src/serve.mjs
+37b01ab0479d5f2a7ab9aac790931c6d88c790465392d9c0b65a105513f3e36b  packages/webui/src/sso-config.mjs
+b624f044d361c648cefa161abe5f2b96e0cd8a83bc7816c9d501a2cd840988ca  packages/webui/src/sso.mjs
+84e31d4beba0de5ed6d192921bd7b016296c8b2a42b3fcf1176663e182320d9e  packages/webui/tests/helpers/fake-oidc.mjs
+ac01037743fcbf1efa641794d3878f113b6206033d2f66cde072a52ccfae1a51  packages/webui/tests/service.test.mjs
+9358e3755e174b61532e2c528e733ffcdb48941cbadb825f1b0254bc55d1920e  packages/webui/tests/sso-browser.test.mjs
+3f8527fd7ae1ffb2bffce3450971f125bd616954b534577ef54249c87f36e248  packages/webui/tests/sso.test.mjs
+f8307d4bd998634467fbed8748157754132b76affac051f320196161ce385e4a  scripts/mosaic-config.mjs
+3301c1fabf616bb961d62f6decd0a46dadb0f399b8ba7f3c2ca60023d2b24c78  scripts/test-config.sh
+7678bb6b45861c3dc6d775fc99269b1db7350ced60b89517d6ebeb4cc161781c  scripts/webui-service.sh
@@ -0,0 +1,59 @@
+# Row 192 (#1690) mutants: `python3 mutants.py <tree> [N ...]`. Each applies to the tree's source, runs one
+# test file (optionally one name pattern) and restores the file from a saved copy, checked by sha256.
+# Killed = test exit != 0.
+import hashlib, os, subprocess, sys, signal
+W = os.path.join(os.path.abspath(sys.argv[1]), 'packages', 'webui')
+if not os.path.isfile(os.path.join(W, 'src', 'sso.mjs')): sys.exit(f'ABORT no packages/webui/src/sso.mjs under {sys.argv[1]}')
+S, B, C, F = 'src/sso.mjs', 'src/serve.mjs', 'src/sso-config.mjs', 'src/public/'
+T, P = 'tests/sso.test.mjs', 'tests/sso-browser.test.mjs'
+M = [
+ ('drop validateApplicationLevelSignature (9b)', S, [("try { await oauth.validateApplicationLevelSignature(entry.as, response, options()); } catch (err) {", "try { } catch (err) {")], T, '^9:'),
+ ('wrap the signature call in a continuing try/catch (9b)', S, [("try { await oauth.validateApplicationLevelSignature(entry.as, response, options()); } catch (err) {", "try { try { await oauth.validateApplicationLevelSignature(entry.as, response, options()); } catch {} } catch (err) {")], T, '^9:'),
+ ('drop the subjects check (10)', S, [("if (name === undefined) {", "if (false) {")], T, '^10:'),
+ ('accept HS* in algs (11)', C, [("export const ALGS = Object.freeze(['PS256',", "export const ALGS = Object.freeze(['HS256', 'none', 'PS256',")], T, '^11: start'),
+ ('take the provider from the query (15)', S, [("const entry = record && providers.get(record.provider);", "const entry = record && providers.get(query.get('provider') ?? record.provider);")], T, '^15:'),
+ ('let the tester listener read cookies (12, F8)', B, [("SIGN_IN_COOKIE.test(req.headers.cookie ?? '') ||", "")], T, '^12:'),
+ ('tester listener takes Authorization (12, F8)', B, [("Object.hasOwn(req.headers, 'authorization') ||", "")], T, '^12:'),
+ ('tester listener takes x-authentik-* (12, F8)', B, [(" || Object.keys(req.headers).some(h => h.startsWith('x-authentik-'))", "")], T, '^12:'),
+ ('skip the login record delete (7)', S, [("if (key !== null) logins.delete(key);\n    // The provider", "// The provider")], T, '^7:'),
+ ('drop HttpOnly from the session cookie (21)', S, [("`${SESSION_COOKIE}=${id}; ${ATTRS}`", "`${SESSION_COOKIE}=${id}; Path=/; Secure; SameSite=Lax`")], T, '^20 and 21'),
+ ('refresh seen on every request (13)', B, [("sso.session(req, { touch: req.method === 'POST' || (req.method === 'GET' && !path.startsWith('/api/')) })", "sso.session(req, { touch: true })")], T, '^13: idle'),
+ ('build redirect_uri from the request Host (22)', S, [("const redirectUri = `${publicOrigin}/auth/callback`;", "let redirectUri = `${publicOrigin}/auth/callback`;"), ("    const query = new URLSearchParams(search);\n", "    const query = new URLSearchParams(search);\n    redirectUri = `https://${req.headers.host}/auth/callback`;\n")], T, '^22:'),
+ ('serve the loopback read path under --sso (22)', B, [("if (sso !== null && !named && !(path === '/healthz' && req.method === 'GET')) return json(res, 403, { error: 'public Host required' });", "")], T, '^22:'),
+ ('bus.js fetchRead ignores 401 sign-in required (F1)', F+'bus.js', [("    if (signInRequired(res, body)) { signOutSso(); throw signedOut(); }\n    if (!res.ok || !body || !Array.isArray(body.rows))", "    if (!res.ok || !body || !Array.isArray(body.rows))")], P, '^a 401'),
+ ('bus.js fetchApi ignores 401 sign-in required (F1)', F+'bus.js', [("    if (signInRequired(res, body)) { signOutSso(); throw signedOut(); }\n    if (!res.ok || !body || typeof body !== 'object'", "    if (!res.ok || !body || typeof body !== 'object'")], P, '^a 401'),
+ ('app.js getJSON ignores 401 sign-in required (24)', F+'app.js', [("    if (signInRequired(res, body)) { sso = true; signOut(); throw signedOut(); }\n    return { ok: res.ok, body };", "    return { ok: res.ok, body };")], P, '^a 401'),
+ ('app.js api() ignores 401 sign-in required (24)', F+'app.js', [("    if (signInRequired(res, result)) { sso = true; signOut(); throw signedOut(); }\n", "")], P, '^a 401'),
+ ('signInRequired takes any 401 (24)', F+'app.js', [("res.status === 401 && body?.error === 'sign-in required'", "res.status === 401")], P, '^a 401'),
+ ('Sign out shown without the sso condition (F7)', F+'app.js', [("if (config.sso === true) { sso = true; $('sign-out').hidden = out(); }", "{ $('sign-out').hidden = out(); }")], P, '^the Sign out'),
+ ('form-action without the end-session origins (CSP)', B, [("form-action 'self'${sso ? sso.formTargets().map(o => ` ${o}`).join('') : ''}`", "form-action 'self'`")], T, '^13: the CSP'),
+ ('import oauth4webapi at module load (copies)', S, [("let oauth;\n", "import * as oauth from 'oauth4webapi';\n"), ("  oauth ??= await import('oauth4webapi');\n", "")], 'tests/pinned-copy.test.mjs', '^serve runs from a copy'),
+ ('restore the r1 relative returnPath (14, webby-0019 B1)', S, [("      if (u.origin !== publicOrigin) return home;\n      const out = new URL(`${publicOrigin}${u.pathname}${u.search}`);\n      return out.origin === publicOrigin ? out.href : home;", "      return u.origin === publicOrigin ? u.pathname + u.search : '/';")], T, '^14:'),
+ ('drop the second origin check (14, sage-1403)', S, [("      return out.origin === publicOrigin ? out.href : home;", "      return `${publicOrigin}${u.pathname}${u.search}`;")], T, '^14:'),
+]
+sha = lambda b: hashlib.sha256(b).hexdigest()
+only = sys.argv[2:]
+os.chdir(W)
+survived = []
+for i, (name, path, pairs, test, pat) in enumerate(M, 1):
+    if only and str(i) not in only: continue
+    orig = open(path, 'rb').read(); h = sha(orig)
+    src = orig.decode()
+    for a, b in pairs:
+        if src.count(a) != 1: sys.exit(f'ABORT {i} {name}: pattern found {src.count(a)} times')
+        src = src.replace(a, b)
+    try:
+        open(path, 'w').write(src)
+        p = subprocess.Popen(['node', '--test', f'--test-name-pattern={pat}', test], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, start_new_session=True)
+        try: out, _ = p.communicate(timeout=240)
+        except subprocess.TimeoutExpired:
+            os.killpg(p.pid, signal.SIGKILL); out, _ = p.communicate(); out += b'\nTIMEOUT'
+        text = out.decode(errors='replace')
+        ran = [l for l in text.splitlines() if l.startswith('ℹ tests ')]
+        verdict = 'KILLED' if p.returncode != 0 else 'SURVIVED'
+        if verdict == 'SURVIVED': survived.append(name)
+        print(f'{i:2} {verdict} {name} [{ran[0] if ran else "no count"}]', flush=True)
+    finally:
+        open(path, 'wb').write(orig)
+        if sha(open(path, 'rb').read()) != h: sys.exit(f'ABORT restore failed for {path}')
+print('survived:', survived or 'none')
@@ -9,7 +9,8 @@
      "version": "0.0.3",
      "license": "UNLICENSED",
      "dependencies": {
-        "@earendil-works/pi-coding-agent": "0.85.1"
+        "@earendil-works/pi-coding-agent": "0.85.1",
+        "oauth4webapi": "3.8.8"
      }
    },
    "node_modules/@anthropic-ai/sdk": {
@@ -1933,6 +1934,15 @@
        "url": "https://opencollective.com/node-fetch"
      }
    },
+    "node_modules/oauth4webapi": {
+      "version": "3.8.8",
+      "resolved": "https://registry.npmjs.org/oauth4webapi/-/oauth4webapi-3.8.8.tgz",
+      "integrity": "sha512-8N28E+a/oxfXWBgOMt+ZP/JUf/XR+IFbvkAEPP3gznXOMv9BpAAwiIj0TFNz3tGTPc0ZQ8zmWBNgN1nAys0gng==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/panva"
+      }
+    },
    "node_modules/openai": {
      "version": "6.40.0",
      "resolved": "https://registry.npmjs.org/openai/-/openai-6.40.0.tgz",
@@ -5,6 +5,7 @@
  "description": "Minimal Mosaic Stack container proof of concept: one Pi agent, four local contract files, one real model request returning MOSAIC_HELLO_OK.",
  "license": "UNLICENSED",
  "dependencies": {
-    "@earendil-works/pi-coding-agent": "0.85.1"
+    "@earendil-works/pi-coding-agent": "0.85.1",
+    "oauth4webapi": "3.8.8"
  }
 }
@@ -129,6 +129,45 @@ Switching the Console, bus or wrapper, changing any unit, and starting or
 stopping either service requires Mos's go for that live step. Agents build
 and test fixtures; they stop before the live sequence.

+## Sign-in in the Console (Q175 phase 1, #1690)
+
+`serve --sso [--send] [--tester-port N]` makes the Console an OpenID Connect
+relying party. It reads `console.sso` from the system config (`publicOrigin`
+and one or more providers, each with its issuer, client id, a client secret
+slot, the signing algorithms it accepts and the subjects allowed in). The
+design is `agents/sage/work/q175-sso/DESIGN.md`. `--sso` can't be combined
+with `--public-host`, `--auth-header`, `--allow-user` or `--proof-*`; `--send`
+takes `--sso` in place of the preview set.
+
+- The client secret is read once at start from
+  `<config dir>/secrets/mosaic-stack/<slot>`. The start refuses a slot that is
+  a symbolic link, not a regular file, owned by another user, has any group or
+  other mode bit, or sits in the repository, the `--checkout` directory or a
+  stack copy. The value is never printed.
+- At start the Console fetches each provider's discovery document and JWKS. A
+  provider that can't be reached (a network error, a timeout, a status other
+  than 200, or a body that isn't JSON) leaves the Console up with that
+  provider's `/auth/login` at 503 and a retry every 5 s, doubling, capped at 5
+  minutes. A document that fails a check (issuer, algorithms, S256, a usable
+  key) refuses the start. `/healthz` adds `sso: { <id>: "ready" | "unreachable"
+  | "refused" }`.
+- The Console listener serves only the Host of `publicOrigin`, whatever port
+  it listens on. Any other Host, a loopback one included, gets 403 `public
+  Host required`, except `GET /healthz`, which stays open on loopback for the
+  status and release gates. The loopback operator path in the preview section
+  above does not exist under `--sso`.
+- Without a session, `/api/*` gets 401 `sign-in required` and a page load gets
+  a 303 to `/auth/login?return=<path>`. The page then shows the signed-out line
+  with a link back to sign-in. A session lasts at most 8 hours and ends after 1
+  hour without a page load or a write; a restart ends every session.
+- The page shows Sign out only under `--sso`. It posts to `/auth/logout`, which
+  ends the session and goes to the provider's end-session endpoint when it has
+  one, or to `/auth/signed-out`.
+- With `--tester-port`, the tester listener refuses any request carrying an
+  `Authorization` header, a `__Host-mosaic_session` or `__Host-mosaic_login`
+  cookie, or an `x-authentik-*` header (403 `tester listener takes no
+  sign-in`). It never serves `/auth/*`.
+
 ## Message a role (row 76, #1570)

 ```sh
@@ -58,8 +58,9 @@ export async function chatHTTP(req, res, { path, search, chat, named, send, prev
      if (one(req, 'origin') !== preview.origin) return refuse(403, 'cross-origin');
    } else {
      if (!send || !named || !preview) return refuse(403, 'read-only');
-      if (one(req, preview.header) !== preview.user) return refuse(401, 'unauthenticated');
-      if (one(req, 'origin') !== `https://${preview.host}`) return refuse(403, 'cross-origin');
+      // Q175 phase 1 (#1690): under --sso the session was checked before this route.
+      if (preview.sso !== true && one(req, preview.header) !== preview.user) return refuse(401, 'unauthenticated');
+      if (one(req, 'origin') !== (preview.origin ?? `https://${preview.host}`)) return refuse(403, 'cross-origin');
    }
    if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site');
  }
@@ -7,20 +7,23 @@ import { views } from '../../bus/src/views.mjs';
 import { loadSystem, socketPath, REPO, rolesDir } from '../../cli/src/config.mjs';
 import { configDir } from '../../business/src/business.mjs';
 import { consoleReads, redactor } from './reads.mjs';
+import { createSso, readSlot } from './sso.mjs';
 import { statSync } from 'node:fs';
 import { isAbsolute } from 'node:path';
 import { ID_PATTERN } from '../../business/src/vocabulary.mjs';
 const args = process.argv.slice(2);
-const usage = 'node packages/webui/src/cli.mjs serve [--port N] [--tester-port N] [--checkout PATH] [--board http://127.0.0.1:7331] [--business ID] [--public-host NAME --auth-header HEADER --allow-user ID [--send] [--proof-header NAME --proof-file PATH]]';
+const usage = 'node packages/webui/src/cli.mjs serve [--port N] [--tester-port N] [--checkout PATH] [--board http://127.0.0.1:7331] [--business ID] [--sso [--send]] [--public-host NAME --auth-header HEADER --allow-user ID [--send] [--proof-header NAME --proof-file PATH]]';
 try {
  if (args.length === 1 && ['--help', '-h'].includes(args[0])) { console.log(usage); process.exit(0); }
  if (args.shift() !== 'serve') throw new Error(usage);
  const options = { board: DEFAULT_BOARD, port: 7330 }, preview = {}, proofFlags = {};
-  let sendOn = false, testerPort = null;
+  let sendOn = false, ssoOn = false, testerPort = null;
  while (args.length) {
    const flag = args.shift();
    // Row 76 (#1570): the one flag without a value.
    if (flag === '--send') { sendOn = true; continue; }
+    // Q175 phase 1 (#1690): the Console signs people in itself, from console.sso in config.json.
+    if (flag === '--sso') { ssoOn = true; continue; }
    const value = args.shift();
    if (!value) throw new Error(`missing value for ${flag}`);
    if (flag === '--port') {
@@ -51,9 +54,10 @@ try {
    else throw new Error(`unknown option: ${flag}`);
  }
  if (testerPort !== null && (testerPort === options.port || testerPort === 7332)) throw new Error('--tester-port must differ from --port and cannot be the forwarded port 7332');
+  if (ssoOn && (Object.keys(preview).length || Object.keys(proofFlags).length)) throw new Error('--sso cannot be combined with --public-host, --auth-header, --allow-user or --proof-*');
  options.preview = previewOptions(preview);
  const proof = proofOptions(proofFlags, options.preview);
-  if (sendOn && !options.preview) throw new Error('--send needs the preview mode (--public-host, --auth-header and --allow-user)');
+  if (sendOn && !options.preview && !ssoOn) throw new Error('--send needs the preview mode (--public-host, --auth-header and --allow-user) or --sso');
  // The bus views (slice 1 S5) need the system config. Without it the
  // board still serves and the bus routes answer not-configured.
  // The Queue, Business and Settings reads (row 54) need no bus; without
@@ -77,31 +81,46 @@ try {
    busLine = `Bus: ${options.business ?? 'the running bus host\'s business'}`;
  } catch (err) {
    const why = redactor({ configDir: configDir() })(err.message);
+    if (ssoOn) throw new Error(`--sso needs the system config (${why})`);
    if (sendOn) throw new Error(`--send needs the bus configured (${why})`);
    if (testerPort !== null) throw new Error(`--tester-port needs the bus configured (${why})`);
    busLine = `Bus: not configured (${why})`;
  }
  const reads = consoleReads({ root: REPO, queueRoot: options.checkout ?? REPO, system, configDir: configDir(), rolesDir: rolesDir(), business: options.business ?? null });
-  const server = await startServer({ board: options.board, port: options.port, bus, reads, preview: options.preview, proof, send, settingsWrite, projectFiles, projectFile, projectSave, chat, nameWrite, assistantStop, instancesWrite, routesWrite });
+  // The sign-in config is checked again here, then each slot file, before anything listens. A
+  // provider that can't be reached starts degraded; one whose discovery is refused stops the start.
+  let sso = null;
+  if (ssoOn) {
+    if (!system.console?.sso) throw new Error('--sso needs console.sso in the system config');
+    const secrets = new Map(system.console.sso.providers.map(p => [p.id, readSlot(configDir(), p, { repo: REPO, checkout: options.checkout ?? null })]));
+    sso = await createSso(system.console.sso, { secrets });
+  }
+  let server;
+  try {
+    server = await startServer({ board: options.board, port: options.port, bus, reads, preview: options.preview, sso, proof, send, settingsWrite, projectFiles, projectFile, projectSave, chat, nameWrite, assistantStop, instancesWrite, routesWrite });
+  } catch (err) { sso?.close(); throw err; }
  let testerServer = null;
  if (testerPort !== null) {
    const call = busCaller({ dataRoot: system.dataRoot, socket: socketPath(system.dataRoot), business: options.business ?? null, cli: TESTER_CLI });
    const testerBus = { ...views({ call }), names: () => call('names'), instances: () => call('instances'), routes: () => call('routes') };
    try {
      testerServer = await startServer({ host: '127.0.0.1', port: testerPort, board: options.board,
-        tester: true, testerProofHeader: proof?.header ?? null, testerAuthHeader: options.preview?.header ?? null, bus: testerBus, reads,
+        tester: true, testerNoSignIn: ssoOn, testerProofHeader: proof?.header ?? null, testerAuthHeader: options.preview?.header ?? null, bus: testerBus, reads,
        projectFiles: args => call('project.files', args), projectFile: args => call('project.file', args),
        instancesWrite: args => call('instances.set', args), routesWrite: args => call('routes.set', args), nameWrite: args => call('name.set', args),
        // Row 177 (#1675): the tester's own chat, through the tester CLI; 7332's stays the human's.
        chat: createChat({ call }),
      });
-    } catch (err) { await new Promise(resolve => server.close(resolve)); throw err; }
+    } catch (err) { sso?.close(); await new Promise(resolve => server.close(resolve)); throw err; }
  }
  const previewLine = options.preview ? `\nPreview: https://${options.preview.host}/ through the proxy, signed-in user from ${options.preview.header}, ${send ? 'reads and human messages to roles (--send); one line per send below' : 'read-only'}` : '';
  const proofLine = `\nProxy: proxy proof ${proof ? 'on' : 'off'}`;
+  // One line per provider: id, issuer, subject count and state. No client id, secret or sub.
+  const health = sso?.health() ?? {};
+  const ssoLines = sso ? `\nSign-in: ${sso.publicOrigin}/ (--sso), ${send ? 'reads and human writes (--send)' : 'read-only'}` + sso.summary().map(p => `\nSign-in provider: ${p.id} issuer ${p.issuer} subjects ${p.subjects} (${health[p.id]})`).join('') : '';
  const queueLine = options.checkout ? '\nQueue: read from the --checkout directory' : '';
-  console.log(`Mosaic Console: http://127.0.0.1:${server.address().port}/\nBoard: ${options.board}\n${busLine}${queueLine}${previewLine}${proofLine}${testerServer ? `\nTester Console: http://127.0.0.1:${testerServer.address().port}/ (binds the tester)` : ''}\nCtrl-C stops this server.`);
-  for (const signal of ['SIGINT', 'SIGTERM']) process.once(signal, () => { server.close(); testerServer?.close(); });
+  console.log(`Mosaic Console: http://127.0.0.1:${server.address().port}/\nBoard: ${options.board}\n${busLine}${queueLine}${previewLine}${ssoLines}${proofLine}${testerServer ? `\nTester Console: http://127.0.0.1:${testerServer.address().port}/ (binds the tester)` : ''}\nCtrl-C stops this server.`);
+  for (const signal of ['SIGINT', 'SIGTERM']) process.once(signal, () => { sso?.close(); server.close(); testerServer?.close(); });
 } catch (err) {
  console.error(`refused: ${err.message}`);
  process.exitCode = 2;
@@ -16,6 +16,11 @@
  // The first one sets body.signed-out (the listener below); after that no Console fetch is made.
  const out = () => document.body.classList.contains('signed-out');
  const signOut = () => { if (!out()) document.dispatchEvent(new Event('mosaic-signed-out')); };
+  // Q175 phase 1 (#1690): under --sso the Console itself answers a read without a session with 401
+  // `sign-in required`; that signs the page out too, and the line links to the Console's sign-in.
+  // Any other 401 stays an error. `sso` comes from /api/config.
+  let sso = false;
+  const signInRequired = (res, body) => res.status === 401 && body?.error === 'sign-in required';
  const signedOut = () => Object.assign(new Error('the sign-in proxy redirected it, so it never reached the Console'), { signedOut: true });
  const labels = { registration: 'registered', 'first-user-message': 'first message', 'tmux-pane': 'tmux pane', 'session-cwd': 'session cwd', 'workspace-git-root': 'git root' };
  const source = value => value ? `<span class="source">${esc(labels[value] || value)}</span>` : '';
@@ -110,6 +115,7 @@
    const res = await fetch(path, { cache: 'no-store', redirect: 'manual' });
    if (res.type === 'opaqueredirect') { signOut(); throw signedOut(); }
    let body; try { body = await res.json(); } catch { body = { error: `HTTP ${res.status}` }; }
+    if (signInRequired(res, body)) { sso = true; signOut(); throw signedOut(); }
    return { ok: res.ok, body };
  }
  function blockNode(b) {
@@ -304,6 +310,7 @@
    const res = await fetch(path, value === undefined ? { cache: 'no-store', redirect: 'manual' } : { method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify(value), redirect: 'manual' });
    if (res.type === 'opaqueredirect') { signOut(); throw signedOut(); }
    const result = await res.json();
+    if (signInRequired(res, result)) { sso = true; signOut(); throw signedOut(); }
    if (!res.ok) throw Object.assign(new Error(result.error || `HTTP ${res.status}`), { status: res.status });
    return result;
  }
@@ -452,7 +459,7 @@
  });
  // Signed out: everything drawn from a Console read goes, because none of it can be refreshed. The
  // line says so once; the send form (bus.js) keeps its draft and receipt. Reload is the way back.
-  document.addEventListener('mosaic-signed-out', () => {
+  document.addEventListener('mosaic-signed-out', e => {
    if (out()) return;
    document.body.classList.add('signed-out');
    clearTimeout(timer); convGen++;
@@ -461,9 +468,13 @@
    for (const id of ['projects', 'waiting', 'seen', 'sessions']) $(id).replaceChildren();
    $('refresh').disabled = $('pause').disabled = true;
    const line = $('signed-out');
-    line.innerHTML = '<p><b>Signed out.</b> Reload the page to sign in.</p>'; line.hidden = false;
+    line.innerHTML = sso || e.detail?.signIn
+      ? `<p><b>Signed out.</b> <a href="/auth/login?${esc(new URLSearchParams({ return: location.pathname + location.search }))}">Sign in again</a>.</p>`
+      : '<p><b>Signed out.</b> Reload the page to sign in.</p>';
+    line.hidden = false; $('sign-out').hidden = true;
    // Focus moves to the line only if what had it is gone or disabled, never out of a form being typed in.
    setTimeout(() => { const a = document.activeElement; if (!a || a === document.body || a.disabled || !a.getClientRects().length) line.focus(); });
  });
-  api('/api/config').then(config => { board = config.board; $('board-url').textContent = `Board: ${board}`; }).catch(err => { if (machine) error(err); }).finally(refresh);
+  // Sign out (sage-1347, F7): a plain same-origin form POST to /auth/logout, shown only under --sso.
+  api('/api/config').then(config => { board = config.board; $('board-url').textContent = `Board: ${board}`; if (config.sso === true) { sso = true; $('sign-out').hidden = out(); } }).catch(err => { if (machine) error(err); }).finally(refresh);
 })();
@@ -30,6 +30,10 @@
  const out = () => document.body.classList.contains('signed-out');
  const signOut = () => { if (!out()) document.dispatchEvent(new Event('mosaic-signed-out')); };
  const signedOut = () => new ReadError('signed-out', 'The sign-in proxy redirected the read.', 0);
+  // Q175 phase 1 (#1690, sage-1340 F1): under --sso a read without a session gets 401 `sign-in
+  // required` from the Console itself. That signs out the same way; any other 401 stays an error.
+  const signInRequired = (res, body) => res.status === 401 && body?.error === 'sign-in required';
+  const signOutSso = () => { if (!out()) document.dispatchEvent(new CustomEvent('mosaic-signed-out', { detail: { signIn: true } })); };
  // `replies` takes a message id as `id`; trail takes `subject`.
  async function fetchRead(verb, subject) {
    if (out()) throw signedOut();
@@ -38,6 +42,7 @@
    catch { throw new ReadError('unreachable', 'The Console server did not answer.', 0); }
    if (res.type === 'opaqueredirect') { signOut(); throw signedOut(); }
    try { body = await res.json(); } catch { throw new ReadError('unreachable', 'The Console server did not answer.', 0); }
+    if (signInRequired(res, body)) { signOutSso(); throw signedOut(); }
    if (!res.ok || !body || !Array.isArray(body.rows)) throw new ReadError(typeof body?.error === 'string' ? body.error : 'invalid-response', typeof body?.message === 'string' ? body.message : `HTTP ${res.status}`, res.status);
    return { ...body, rows: body.rows, at: body.at };
  }
@@ -50,6 +55,7 @@
    try { res = await fetch(`/api/${path}`, { cache: 'no-store', redirect: 'manual' }); } catch { throw unreachable(); }
    if (res.type === 'opaqueredirect') { signOut(); throw signedOut(); }
    try { body = await res.json(); } catch { throw unreachable(); }
+    if (signInRequired(res, body)) { signOutSso(); throw signedOut(); }
    if (!res.ok || !body || typeof body !== 'object' || Array.isArray(body)) throw Object.assign(new ReadError(typeof body?.error === 'string' ? body.error : 'invalid-response', typeof body?.message === 'string' ? body.message : `HTTP ${res.status}`, res.status), { module: true });
    return body;
  }
@@ -9,7 +9,7 @@
 <header class="cmdbar"><a href="/" class="wordmark"><svg class="mark" viewBox="0 0 16 17" aria-hidden="true"><use href="/icons.svg#mark"/></svg>Mosaic<small>Console</small></a>
 <button type="button" class="cmdk" id="cmdk" aria-haspopup="dialog" aria-controls="cmdk-dialog"><svg class="i" aria-hidden="true"><use href="/icons.svg#i-search"/></svg><span>Go to a view, decision or task</span><kbd>Ctrl K</kbd></button>
 <p class="fresh" id="fresh"><span id="fresh-board"></span><span id="fresh-bus"></span></p>
-<div class="cmd-right"><label>Palette<select id="palette"></select></label><label>Appearance<select id="mode"><option value="system">system</option><option value="light">light</option><option value="dim">dim</option><option value="dark">dark</option></select></label><button class="btn" id="refresh" type="button">Refresh</button><button class="btn" id="pause" type="button" aria-pressed="false">Pause</button></div></header>
+<div class="cmd-right"><label>Palette<select id="palette"></select></label><label>Appearance<select id="mode"><option value="system">system</option><option value="light">light</option><option value="dim">dim</option><option value="dark">dark</option></select></label><button class="btn" id="refresh" type="button">Refresh</button><button class="btn" id="pause" type="button" aria-pressed="false">Pause</button><form id="sign-out" method="post" action="/auth/logout" hidden><button class="btn" type="submit">Sign out</button></form></div></header>
 <div class="frame">
 <nav class="tree" aria-label="Console"><h2 class="tree-title">Console</h2><ul class="s1-sections" id="sections"></ul><div id="board-tree"><h2 class="tree-title">Projects</h2><div id="projects"><p class="muted">Loading projects…</p></div><p class="small muted">Select a project to filter sessions. Waiting on you always shows all projects.</p></div></nav>
 <main id="main" class="content" tabindex="-1"><div id="signed-out" class="banner ref" role="alert" tabindex="-1" hidden></div><div id="bus-down" class="banner err" role="alert" hidden></div><div class="page-head" id="board-head"><div><h1>Control board</h1><p id="status" class="small muted" role="status">Loading board…</p></div><div class="filters"><label><input id="show-machine" type="checkbox">Show machine sessions</label></div></div>
@@ -61,6 +61,8 @@ async function body(req, max = 4096) {
 // Row 65 (mos-0840) adds `routes`: each instance's harness, model, thinking and fallback.
 const BUS_VERBS = ['inbox', 'tasks', 'agents', 'trail', 'decisions', 'credentials', 'replies', 'messages', 'usage', 'limits', 'names', 'instances', 'routes'];
 const DECISION_LISTS = ['roles', 'recent'];
+// Q175 phase 1 (#1690, F8): either sign-in cookie, which the tester listener refuses under --sso.
+const SIGN_IN_COOKIE = /(?:^|;)\s*__host-mosaic_(?:session|login)\s*=/i;
 // Row 177 (#1675): the chat writes the tester listener lets through, exactly the four chatHTTP routes.
 const TESTER_CHAT_WRITE = /^\/api\/chat\/(?:projects|threads|threads\/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\/(?:messages|open))$/i;
 async function busRead(res, bus, verb, search) {
@@ -160,14 +162,18 @@ async function busRead(res, bus, verb, search) {
 // broker's to refuse. Nothing retries; an outcome the bus can't confirm is reported as unknown.
 const SEND_KEYS = ['to', 'body', 'in_reply_to'];
 const one = (req, name) => (req.headersDistinct[name]?.length === 1 ? req.headersDistinct[name][0] : null);
+// Q175 phase 1 (#1690): under --sso the writer comes from a session the handler already checked,
+// so it carries `sso: true` and the public origin; the preview writer still checks its header.
+const signedIn = (req, p) => p.sso === true || one(req, p.header) === p.user;
+const ownOrigin = p => p.origin ?? `https://${p.host}`;
 async function busSend(req, res, { send, preview, log }) {
-  if (one(req, preview.header) !== preview.user) return json(res, 401, { error: 'sign-in required' });
+  if (!signedIn(req, preview)) return json(res, 401, { error: 'sign-in required' });
  let to = null;
  // `to` is quoted and cut short so a crafted value can't forge a log line.
  const line = outcome => log(`${new Date().toISOString()} send user=${JSON.stringify(preview.user)} to=${typeof to === 'string' ? JSON.stringify(to.slice(0, 64)) : 'none'} ${outcome}`);
  // `sent` tells the page which it was: false, nothing was written; 'unknown', it may have been.
  const refuse = (status, error, message, sent = false) => { line(`error=${error}`); return json(res, status, { error, message, sent }); };
-  if (one(req, 'origin') !== `https://${preview.host}`) return refuse(403, 'cross-origin request refused', 'a send needs the Console\'s own Origin');
+  if (one(req, 'origin') !== ownOrigin(preview)) return refuse(403, 'cross-origin request refused', 'a send needs the Console\'s own Origin');
  if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site request refused', 'a send needs Sec-Fetch-Site: same-origin');
  let value;
  try { value = JSON.parse((await body(req, 16384)).toString('utf8')); } catch (err) { return refuse(400, 'invalid-request', err.message); }
@@ -241,10 +247,10 @@ export function proofOptions({ proofHeader, proofFile } = {}, preview = null) {
 // REQ-WEB-1: same signed-in send boundary, a distinct strict settings payload.
 async function settingsSend(req, res, { settingsWrite, preview, log }) {
  const refuse = (status, error, message) => json(res, status, { error, message, sent: false });
-  if (one(req, preview.header) !== preview.user) {
+  if (!signedIn(req, preview)) {
    return refuse(401, 'sign-in required', 'sign in again');
  }
-  if (one(req, 'origin') !== `https://${preview.host}`) {
+  if (one(req, 'origin') !== ownOrigin(preview)) {
    return refuse(403, 'cross-origin request refused', 'settings need the Console origin');
  }
  if (one(req, 'sec-fetch-site') !== 'same-origin') {
@@ -292,8 +298,8 @@ async function seatSend(req, res, { route, write, preview, log }) {
  // The instance is quoted and cut short so a crafted value can't forge a log line.
  const line = outcome => log(`${new Date().toISOString()} ${route.kind} user=${JSON.stringify(preview.user)} instance=${quoted(instance)} ${outcome}`);
  const refuse = (status, error, message, sent = false) => { line(`error=${error}`); return json(res, status, { error, message, sent }); };
-  if (!preview.tester && one(req, preview.header) !== preview.user) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
-  if (one(req, 'origin') !== (preview.origin ?? `https://${preview.host}`)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
+  if (!preview.tester && !signedIn(req, preview)) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
+  if (one(req, 'origin') !== ownOrigin(preview)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
  if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site request refused', 'this needs same-origin Fetch Metadata');
  let value;
  try { value = JSON.parse((await body(req)).toString('utf8')); } catch (err) { return refuse(400, 'invalid-request', err.message); }
@@ -335,8 +341,8 @@ async function instanceSend(req, res, { instancesWrite, preview, log }) {
  // The instance is quoted and cut short so a crafted value can't forge a log line. Vars are never logged.
  const line = outcome => log(`${new Date().toISOString()} instance user=${JSON.stringify(preview.user)} instance=${quoted(instance)} ${outcome}`);
  const refuse = (status, error, message, sent = false) => { line(`error=${error}`); return json(res, status, { error, message, sent }); };
-  if (!preview.tester && one(req, preview.header) !== preview.user) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
-  if (one(req, 'origin') !== (preview.origin ?? `https://${preview.host}`)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
+  if (!preview.tester && !signedIn(req, preview)) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
+  if (one(req, 'origin') !== ownOrigin(preview)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
  if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site request refused', 'this needs same-origin Fetch Metadata');
  let value;
  try { value = JSON.parse((await body(req, 16384)).toString('utf8')); } catch (err) { return refuse(400, 'invalid-request', err.message); }
@@ -382,8 +388,8 @@ async function routesSend(req, res, { routesWrite, preview, log }) {
  let names = [];
  const line = outcome => log(`${new Date().toISOString()} routes user=${JSON.stringify(preview.user)} instances=${quoted(names.join(','))} ${outcome}`);
  const refuse = (status, error, message, sent = false) => { line(`error=${error}`); return json(res, status, { error, message, sent }); };
-  if (!preview.tester && one(req, preview.header) !== preview.user) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
-  if (one(req, 'origin') !== (preview.origin ?? `https://${preview.host}`)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
+  if (!preview.tester && !signedIn(req, preview)) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
+  if (one(req, 'origin') !== ownOrigin(preview)) return refuse(403, 'cross-origin request refused', 'this needs the Console\'s own Origin');
  if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site request refused', 'this needs same-origin Fetch Metadata');
  let value;
  try { value = JSON.parse((await body(req, 16384)).toString('utf8')); } catch (err) { return refuse(400, 'invalid-request', err.message); }
@@ -420,8 +426,8 @@ async function projectFileSend(req, res, { projectSave, preview, log }) {
  const line = outcome => log(`${new Date().toISOString()} project-file user=${JSON.stringify(preview.user)} project=${quoted(target?.project)} path=${quoted(target?.path)} ${outcome}`);
  // `sent` tells the page which it was: false, nothing was written; 'unknown', it may have been.
  const refuse = (status, error, message, sent = false) => { line(`error=${error}`); return json(res, status, { error, message, sent }); };
-  if (one(req, preview.header) !== preview.user) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
-  if (one(req, 'origin') !== `https://${preview.host}`) return refuse(403, 'cross-origin request refused', 'a save needs the Console\'s own Origin');
+  if (!signedIn(req, preview)) return json(res, 401, { error: 'sign-in required', message: 'sign in again', sent: false });
+  if (one(req, 'origin') !== ownOrigin(preview)) return refuse(403, 'cross-origin request refused', 'a save needs the Console\'s own Origin');
  if (one(req, 'sec-fetch-site') !== 'same-origin') return refuse(403, 'cross-site request refused', 'a save needs same-origin Fetch Metadata');
  let value;
  try { value = JSON.parse((await body(req, FILE_SAVE_MAX)).toString('utf8')); } catch (err) { return refuse(400, 'invalid-request', err.message); }
@@ -460,13 +466,17 @@ async function projectFileRead(res, read, path, search) {
    return json(res, busStatus(code), { error: code, message: err instanceof BusReadError ? err.message : code });
  }
 }
-// `send` is the bus write (row 76): `args => Promise<{id}>`, only with the preview mode. `log`
+// `send` is the bus write (row 76): `args => Promise<{id}>`, only with the preview mode or `sso`.
+// `sso` is createSso() from sso.mjs (Q175 phase 1): the human listener signs people in itself.
+// `testerNoSignIn` makes the tester listener refuse anything that looks like a sign-in (--sso). `log`
 // takes one line per send attempt that got past sign-in; never the body. `fieldsFile` is for
 // tests; the field table is otherwise the committed packages/tasks/fields.json.
-export async function startServer({ host = '127.0.0.1', port = 7330, board = DEFAULT_BOARD, timeout = 20000, bus = null, reads = null, preview = null, tester = false, testerAuthHeader = null, proof = null, testerProofHeader = null, send = null, settingsWrite = null, projectFiles = null, projectFile = null, projectSave = null, chat = null, nameWrite = null, assistantStop = null, instancesWrite = null, routesWrite = null, log = line => console.log(line), fieldsFile = undefined } = {}) {
+export async function startServer({ host = '127.0.0.1', port = 7330, board = DEFAULT_BOARD, timeout = 20000, bus = null, reads = null, preview = null, sso = null, tester = false, testerNoSignIn = false, testerAuthHeader = null, proof = null, testerProofHeader = null, send = null, settingsWrite = null, projectFiles = null, projectFile = null, projectSave = null, chat = null, nameWrite = null, assistantStop = null, instancesWrite = null, routesWrite = null, log = line => console.log(line), fieldsFile = undefined } = {}) {
  if (!isLoopback(host)) throw new Error('refusing to bind to non-loopback host');
  if (host === 'localhost') host = '127.0.0.1';
  if (tester && preview !== null) throw new Error('tester listener cannot use preview mode');
+  if (tester && sso !== null) throw new Error('tester listener cannot use sso');
+  if (sso !== null && (preview !== null || proof !== null)) throw new Error('--sso cannot be combined with --auth-header, --allow-user or --proof-*');
  if (tester && host !== '127.0.0.1') throw new Error('tester listener must bind 127.0.0.1');
  // Row 177 (#1675): chat is allowed. The tester listener's chat binds the tester, so the bus keeps it on tester threads.
  if (tester && [send, settingsWrite, projectSave, assistantStop].some(value => value !== null)) throw new Error('tester listener permits only instance, route, name and chat writes');
@@ -476,21 +486,26 @@ export async function startServer({ host = '127.0.0.1', port = 7330, board = DEF
    throw new Error('preview mode needs --public-host, --auth-header and --allow-user together');
  }
  if (proof !== null && (preview === null || tester)) throw new Error('proxy proof needs preview mode');
-  if (send !== null && (preview === null || typeof send !== 'function')) throw new Error('--send needs the preview mode (--public-host, --auth-header and --allow-user)');
+  if (send !== null && ((preview === null && sso === null) || typeof send !== 'function')) throw new Error('--send needs the preview mode (--public-host, --auth-header and --allow-user) or --sso');
  const server = createServer(async (req, res) => {
    res.setHeader('x-content-type-options', 'nosniff');
    res.setHeader('referrer-policy', 'no-referrer');
-    res.setHeader('content-security-policy', "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; connect-src 'self'; font-src 'self'; object-src 'none'; base-uri 'none'; frame-ancestors 'none'; form-action 'self'");
+    // Under --sso the Sign out form's POST is redirected to the provider's end-session endpoint, and
+    // browsers apply form-action to that redirect, so those origins (from discovery) are allowed too.
+    res.setHeader('content-security-policy', `default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; connect-src 'self'; font-src 'self'; object-src 'none'; base-uri 'none'; frame-ancestors 'none'; form-action 'self'${sso ? sso.formTargets().map(o => ` ${o}`).join('') : ''}`);
    // Presence, even with an empty value: never turn the public listener into a tester ingress.
    if (!tester && Object.hasOwn(req.headers, 'x-mosaic-tester')) return json(res, 403, { error: 'tester listener required' });
    if (tester && testerAuthHeader && Object.hasOwn(req.headers, testerAuthHeader.toLowerCase())) return json(res, 403, { error: 'proxy header refused' });
    if (tester && testerProofHeader && Object.hasOwn(req.headers, testerProofHeader.toLowerCase())) return json(res, 403, { error: 'proxy proof header refused' });
+    // Under --sso the tester listener reads no cookie and takes no sign-in of any kind (design section 6).
+    if (tester && testerNoSignIn && (Object.hasOwn(req.headers, 'authorization') || SIGN_IN_COOKIE.test(req.headers.cookie ?? '') || Object.keys(req.headers).some(h => h.startsWith('x-authentik-'))))
+      return json(res, 403, { error: 'tester listener takes no sign-in' });
    let path, search;
    // Node keeps the first of repeated Host headers; a second one (a loopback Host, then NAME) is
    // never legitimate, so it is refused before any check reads the Host.
    if ((req.headersDistinct.host?.length ?? 0) > 1) return json(res, 400, { error: 'repeated Host refused' });
    // Preview mode: a request for the public name, exactly, as the proxy forwards it.
-    const named = preview !== null && (req.headers.host ?? '').toLowerCase() === preview.host;
+    const named = preview !== null ? (req.headers.host ?? '').toLowerCase() === preview.host : sso !== null && (req.headers.host ?? '').toLowerCase() === sso.publicHost;
    // The proof precedes every auth-header read, including the wrong-Host fence.
    if (proof !== null) {
      const values = req.headersDistinct[proof.header];
@@ -512,19 +527,34 @@ export async function startServer({ host = '127.0.0.1', port = 7330, board = DEF
      }
      ({ pathname: path, search } = new URL(req.url, 'http://localhost'));
    } catch { return json(res, 400, { error: 'invalid URL' }); }
+    // Under --sso the human listener serves only the public Host, whatever its port; GET /healthz
+    // alone stays open on a loopback Host for the status and release gates (Q-C).
+    if (sso !== null && !named && !(path === '/healthz' && req.method === 'GET')) return json(res, 403, { error: 'public Host required' });
    // No CORS. JSON content type and same-origin checks keep browser forms out.
-    if (req.headers.origin && req.headers.origin !== (named ? `https://${preview.host}` : `http://${req.headers.host}`)) return json(res, 403, { error: 'cross-origin request refused' });
-    if (named) {
+    if (req.headers.origin && req.headers.origin !== (named ? (sso ? sso.publicOrigin : `https://${preview.host}`) : `http://${req.headers.host}`)) return json(res, 403, { error: 'cross-origin request refused' });
+    let signer = preview;
+    if (sso !== null && named) {
+      if (path.startsWith('/auth/')) return sso.handle(req, res, path, search);
+      // Only a page load or a write keeps a session alive; the page's background reads don't (Q-D).
+      const session = path === '/healthz' ? null : sso.session(req, { touch: req.method === 'POST' || (req.method === 'GET' && !path.startsWith('/api/')) });
+      if (!session && path !== '/healthz') {
+        if (path.startsWith('/api/') || req.method !== 'GET') return json(res, 401, { error: 'sign-in required' });
+        res.writeHead(303, { location: `/auth/login?return=${encodeURIComponent(path + search)}`, 'cache-control': 'no-store' });
+        return res.end();
+      }
+      if (session) signer = { sso: true, user: session.name, host: sso.publicHost, origin: sso.publicOrigin };
+    }
+    if (named && preview !== null) {
      // One value, equal to the user id; the proxy strips client copies and sets it after sign-in.
      const values = req.headersDistinct[preview.header];
      if (!values || values.length !== 1 || values[0] !== preview.user) return json(res, 401, { error: 'sign-in required' });
    }
-    const writer = tester ? { tester: true, user: 'tester', origin: `http://127.0.0.1:${server.address().port}` } : preview;
+    const writer = tester ? { tester: true, user: 'tester', origin: `http://127.0.0.1:${server.address().port}` } : signer;
    if (tester && !['GET', 'HEAD'].includes(req.method) && !['/api/instances', '/api/routes', '/api/name'].includes(path) && !TESTER_CHAT_WRITE.test(path))
      return json(res, 403, { error: 'read-only', sent: false });
    if(path==='/api/settings'&&req.method==='POST'){
      if(!send||!settingsWrite||!named)return json(res,403,{error:'read-only',sent:false});
-      return settingsSend(req,res,{settingsWrite,preview,log});
+      return settingsSend(req,res,{settingsWrite,preview:signer,log});
    }
    if (Object.hasOwn(SEAT_ROUTES, path)) {
      if (req.method !== 'POST') return json(res, 405, { error: 'method not allowed' });
@@ -544,18 +574,18 @@ export async function startServer({ host = '127.0.0.1', port = 7330, board = DEF
    }
    if (path === '/api/project-file' && req.method === 'POST') {
      if (!send || !projectSave || !named) return json(res, 403, { error: 'read-only', sent: false });
-      return projectFileSend(req, res, { projectSave, preview, log });
+      return projectFileSend(req, res, { projectSave, preview: signer, log });
    }
    // Message sending has its own bounded payload and repeats the identity check.
    if (send && path === '/api/bus/message') {
      if (req.method !== 'POST') return json(res, 405, { error: 'method not allowed' });
-      return busSend(req, res, { send, preview, log });
+      return busSend(req, res, { send, preview: signer, log });
    }
    if (path === '/api/chat' || path.startsWith('/api/chat/')) {
      return chatHTTP(req, res, { path, search, chat, named, send, preview: writer, log });
    }
    // Nothing else but GET and HEAD gets past here in preview mode, whatever the Host.
-    if (preview !== null && req.method !== 'GET' && req.method !== 'HEAD') return json(res, 403, { error: 'read-only', message: 'the Console preview is read-only' });
+    if ((preview !== null || sso !== null) && req.method !== 'GET' && req.method !== 'HEAD') return json(res, 403, { error: 'read-only', message: 'the Console preview is read-only' });
    // The conversation routes (#1507, CHAT-02) keep their query; the board validates it.
    const conversation = path === '/api/conversations' || path === '/api/conversation';
    const allowed = path === '/api/board' || conversation ? 'GET' : ['/api/seen', '/api/reply'].includes(path) ? 'POST' : null;
@@ -607,8 +637,8 @@ export async function startServer({ host = '127.0.0.1', port = 7330, board = DEF
    if (req.method !== 'GET' && req.method !== 'HEAD') return json(res, 405, { error: 'method not allowed' });
    // `send`: the page shows the composer only where a send can pass (the public name, --send on).
    // `edit`: the editor shows Save only where a save can pass, the same test as the route's.
-    if (path === '/api/config') return json(res, 200, { board: upstream, ...(tester ? { tester: true } : {}), send: !tester && Boolean(send) && named, edit: !tester && Boolean(send) && Boolean(projectSave) && named });
-    if (path === '/healthz') return json(res, 200, { ok: true });
+    if (path === '/api/config') return json(res, 200, { board: upstream, ...(tester ? { tester: true } : {}), ...(sso ? { sso: true } : {}), send: !tester && Boolean(send) && named, edit: !tester && Boolean(send) && Boolean(projectSave) && named });
+    if (path === '/healthz') return json(res, 200, { ok: true, ...(sso ? { sso: sso.health() } : {}) });
    if (path === '/favicon.ico') { res.writeHead(204); return res.end(); }
    const file = files.get(path);
    if (!file) return json(res, 404, { error: 'not found' });
@@ -0,0 +1,75 @@
+// Q175 phase 1 (#1690): the shape of config.json's optional `console` key. The one loader,
+// scripts/mosaic-config.mjs, runs this on every read, so a bad key refuses the config for every
+// tool (design section 4, C1). The Console's --sso start runs it again before it uses the value.
+// Shape only: nothing here touches the network or a slot file. A refusal names the key path and
+// never quotes a value, so a refusal can't print a client id or a subject.
+
+// The asymmetric algorithms oauth4webapi 3.8.8 verifies (its supported(), build/index.js). No HS*
+// and no none, so a client secret can never be a signing key.
+export const ALGS = Object.freeze(['PS256', 'ES256', 'RS256', 'PS384', 'ES384', 'RS384', 'PS512', 'ES512', 'RS512', 'Ed25519', 'EdDSA', 'ML-DSA-44', 'ML-DSA-65', 'ML-DSA-87']);
+const PROVIDER_ID = /^[a-z0-9-]{1,32}$/;
+const SLOT = /^[a-z0-9-]{1,64}$/;
+const SUB = /^[\x21-\x7e]{1,255}$/;
+const CLIENT_ID = /^[\x21-\x7e]{1,255}$/;
+// The name goes where the preview's --allow-user went (serve.mjs USER): visible ASCII, no comma.
+const NAME = /^[\x21-\x2b\x2d-\x7e]{1,64}$/;
+// The bus keeps these for the tester and the human role (section 6), so no subject can sign in as one.
+const RESERVED_NAMES = ['tester', 'human'];
+
+const object = v => typeof v === 'object' && v !== null && !Array.isArray(v);
+function refuse(where, why) {
+  throw new Error(`${where} ${why}`);
+}
+function keys(value, where, allowed, required = allowed) {
+  if (!object(value)) refuse(where, 'must be a JSON object');
+  for (const key of Object.keys(value)) if (!allowed.includes(key)) refuse(`${where}.${key}`, 'is not a supported key');
+  for (const key of required) if (!Object.hasOwn(value, key)) refuse(`${where}.${key}`, 'is required');
+}
+function httpsURL(value, where) {
+  let url;
+  if (typeof value !== 'string' || value.length > 512) refuse(where, 'must be an https URL of at most 512 characters');
+  try { url = new URL(value); } catch { refuse(where, 'must be an https URL'); }
+  if (url.protocol !== 'https:' || url.username || url.password || url.search || url.hash || value.includes('?') || value.includes('#')) {
+    refuse(where, 'must be https with no credentials, query or fragment');
+  }
+  return url;
+}
+
+// Returns the value unchanged when it passes; throws an Error naming the bad key path otherwise.
+export function checkConsole(value, where = 'console') {
+  keys(value, where, ['sso']);
+  const sso = value.sso, at = `${where}.sso`;
+  keys(sso, at, ['publicOrigin', 'providers']);
+  const origin = httpsURL(sso.publicOrigin, `${at}.publicOrigin`);
+  if (origin.origin !== sso.publicOrigin) refuse(`${at}.publicOrigin`, 'must be an https origin with no path, query, fragment or trailing slash');
+  if (!Array.isArray(sso.providers) || sso.providers.length === 0 || sso.providers.length > 8) refuse(`${at}.providers`, 'must be a list of 1 to 8 providers');
+  const ids = new Set();
+  sso.providers.forEach((p, i) => {
+    const pat = `${at}.providers[${i}]`;
+    keys(p, pat, ['id', 'issuer', 'clientId', 'clientSecret', 'algs', 'subjects']);
+    if (typeof p.id !== 'string' || !PROVIDER_ID.test(p.id)) refuse(`${pat}.id`, 'must match [a-z0-9-]{1,32}');
+    if (ids.has(p.id)) refuse(`${pat}.id`, 'repeats an earlier provider id');
+    ids.add(p.id);
+    httpsURL(p.issuer, `${pat}.issuer`);
+    if (typeof p.clientId !== 'string' || !CLIENT_ID.test(p.clientId)) refuse(`${pat}.clientId`, 'must be 1 to 255 visible characters');
+    keys(p.clientSecret, `${pat}.clientSecret`, ['slot']);
+    if (typeof p.clientSecret.slot !== 'string' || !SLOT.test(p.clientSecret.slot)) refuse(`${pat}.clientSecret.slot`, 'must match [a-z0-9-]{1,64}');
+    if (!Array.isArray(p.algs) || p.algs.length === 0) refuse(`${pat}.algs`, 'must be a non-empty list');
+    p.algs.forEach((alg, j) => {
+      if (!ALGS.includes(alg)) refuse(`${pat}.algs[${j}]`, `must be one of ${ALGS.join(', ')}; HS* and none are refused`);
+    });
+    if (new Set(p.algs).size !== p.algs.length) refuse(`${pat}.algs`, 'repeats an algorithm');
+    if (!Array.isArray(p.subjects) || p.subjects.length === 0 || p.subjects.length > 64) refuse(`${pat}.subjects`, 'must be a list of 1 to 64 subjects');
+    const subs = new Set();
+    p.subjects.forEach((s, j) => {
+      const sat = `${pat}.subjects[${j}]`;
+      keys(s, sat, ['sub', 'name']);
+      if (typeof s.sub !== 'string' || !SUB.test(s.sub)) refuse(`${sat}.sub`, 'must be 1 to 255 visible characters');
+      if (subs.has(s.sub)) refuse(`${sat}.sub`, 'repeats an earlier subject');
+      subs.add(s.sub);
+      if (typeof s.name !== 'string' || !NAME.test(s.name)) refuse(`${sat}.name`, 'must be 1 to 64 visible characters');
+      if (RESERVED_NAMES.includes(s.name.toLowerCase())) refuse(`${sat}.name`, `must not be ${RESERVED_NAMES.join(' or ')}`);
+    });
+  });
+  return value;
+}
@@ -0,0 +1,347 @@
+// Q175 phase 1 (#1690, design agents/sage/work/q175-sso/DESIGN.md): the Console as an OIDC relying
+// party. Used only by the human listener under --sso; startServer refuses it on the tester listener.
+// Every URL handed to a provider is built from the configured publicOrigin, never from a request's
+// Host. A refusal logs one fixed code and the provider id, never an exception, its message or its
+// cause: oauth4webapi's errors carry token bodies and claims there.
+import { createHash, randomBytes } from 'node:crypto';
+import { closeSync, constants, fstatSync, lstatSync, openSync, readFileSync, realpathSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join, relative, isAbsolute, resolve } from 'node:path';
+import { checkConsole } from './sso-config.mjs';
+
+// oauth4webapi loads in createSso, not here: cli.mjs imports this module on every start, and a
+// Console without --sso must not need the package (pinned-copy.test.mjs builds copies whose lock
+// installs nothing). A real copy installs it from the root lock.
+let oauth;
+
+export const SESSION_COOKIE = '__Host-mosaic_session';
+export const LOGIN_COOKIE = '__Host-mosaic_login';
+const ATTRS = 'Path=/; Secure; HttpOnly; SameSite=Lax';
+const LOGIN_MAX_AGE = 600;
+const SESSION_ABSOLUTE = 8 * 3600 * 1000, SESSION_IDLE = 3600 * 1000;
+const MAX_SESSIONS = 64, MAX_LOGINS = 32;
+const FETCH_TIMEOUT = 10000;
+const RETRY_CAP = 300000;
+const CODES = new Set(['login-record-missing', 'state-mismatch', 'auth-error-response', 'grant-failed', 'id-token-invalid', 'signature-invalid', 'alg-refused', 'issuer-mismatch', 'subject-unknown', 'discovery-failed', 'jwks-failed']);
+
+const sha256 = value => createHash('sha256').update(value).digest('hex');
+const escape = text => String(text).replace(/[&<>"']/g, c => `&#${c.charCodeAt(0)};`);
+const under = (parent, child) => { const rel = relative(parent, child); return rel === '' || (!rel.startsWith('..') && !isAbsolute(rel)); };
+
+// The slot file holding a provider's client secret (design section 4, D1). Only the Console's --sso
+// start calls this. A refusal names the provider and the check, never the path's contents.
+export function readSlot(configDir, provider, { repo, checkout = null, copies = join(process.env.XDG_DATA_HOME || join(homedir(), '.local', 'share'), 'mosaic-stack', 'copies') } = {}) {
+  const where = `console.sso provider ${provider.id} client secret slot`;
+  const file = join(resolve(configDir), 'secrets', 'mosaic-stack', provider.clientSecret.slot);
+  let st;
+  try { st = lstatSync(file); } catch { throw new Error(`${where} is missing`); }
+  if (st.isSymbolicLink()) throw new Error(`${where} must not be a symbolic link`);
+  let fd, real, text;
+  try {
+    fd = openSync(file, constants.O_RDONLY | constants.O_NOFOLLOW | constants.O_NONBLOCK);
+    st = fstatSync(fd);
+    if (!st.isFile()) throw new Error(`${where} must be a regular file`);
+    if (st.uid !== process.getuid()) throw new Error(`${where} must be owned by the Console's user`);
+    if (st.mode & 0o077) throw new Error(`${where} must have no group or other permission bits`);
+    real = realpathSync(file);
+    for (const root of [repo, checkout, copies].filter(Boolean)) {
+      let base;
+      try { base = realpathSync(root); } catch { base = resolve(root); }
+      if (under(base, real)) throw new Error(`${where} must not be inside the repository or a stack copy`);
+    }
+    text = readFileSync(fd, 'utf8');
+  } catch (err) {
+    throw err.message?.startsWith(where) ? err : new Error(`${where} is not readable`);
+  } finally {
+    if (fd !== undefined) closeSync(fd);
+  }
+  const secret = text.endsWith('\n') ? text.slice(0, -1) : text;
+  if (!secret || /[\r\n]/.test(secret)) throw new Error(`${where} must hold one non-empty line`);
+  return secret;
+}
+
+export function cookies(req, name) {
+  const found = [];
+  for (const part of (req.headers.cookie ?? '').split(';')) {
+    const at = part.indexOf('=');
+    if (at > 0 && part.slice(0, at).trim() === name) found.push(part.slice(at + 1).trim());
+  }
+  return found;
+}
+
+// The JWKS check at discovery, the same filter the library's key selection uses (kty, alg, use,
+// key_ops, crv; RSA at least 2048 bits), without a kid since no token is at hand yet.
+function usableKey(jwk, alg) {
+  const kty = { RS: 'RSA', PS: 'RSA', ES: 'EC', Ed: 'OKP', ML: 'AKP' }[alg.slice(0, 2)];
+  if (jwk === null || typeof jwk !== 'object' || jwk.kty !== kty) return false;
+  if (jwk.alg !== undefined && jwk.alg !== alg) return false;
+  if (jwk.use !== undefined && jwk.use !== 'sig') return false;
+  if (Array.isArray(jwk.key_ops) && !jwk.key_ops.includes('verify')) return false;
+  const crv = { ES256: 'P-256', ES384: 'P-384', ES512: 'P-521', Ed25519: 'Ed25519', EdDSA: 'Ed25519' }[alg];
+  if (crv && jwk.crv !== crv) return false;
+  if (kty === 'RSA' && (typeof jwk.n !== 'string' || Buffer.from(jwk.n, 'base64url').length * 8 < 2048)) return false;
+  return true;
+}
+
+class Unreachable extends Error {}
+class Refused extends Error {}
+const https = value => { try { return new URL(value).protocol === 'https:'; } catch { return false; } };
+
+// One provider's discovery and JWKS. Throws Unreachable (network, timeout, a status other than 200,
+// a body that isn't JSON) or Refused (a JSON document that fails a check). Q-B, design section 4.
+async function discover(p, fetchOptions) {
+  let response, text;
+  const options = () => ({ ...fetchOptions, signal: AbortSignal.timeout(FETCH_TIMEOUT) });
+  try {
+    response = await oauth.discoveryRequest(new URL(p.issuer), options());
+    if (response.status !== 200 || !/^application\/json\b/i.test(response.headers.get('content-type') ?? '')) throw new Error();
+    text = await response.text();
+    JSON.parse(text);
+  } catch { throw new Unreachable(); }
+  let as;
+  try {
+    as = await oauth.processDiscoveryResponse(new URL(p.issuer), new Response(text, { status: 200, headers: { 'content-type': 'application/json' } }));
+  } catch { throw new Refused(); }
+  if (as.issuer !== p.issuer) throw new Refused();
+  if (!Array.isArray(as.id_token_signing_alg_values_supported) || !p.algs.some(a => as.id_token_signing_alg_values_supported.includes(a))) throw new Refused();
+  if (!Array.isArray(as.code_challenge_methods_supported) || !as.code_challenge_methods_supported.includes('S256')) throw new Refused();
+  if (![as.authorization_endpoint, as.token_endpoint, as.jwks_uri].every(https)) throw new Refused();
+  if (as.end_session_endpoint !== undefined && !https(as.end_session_endpoint)) throw new Refused();
+  let jwks;
+  try {
+    const fetcher = fetchOptions[oauth.customFetch] ?? fetch;
+    const res = await fetcher(as.jwks_uri, { method: 'GET', headers: { accept: 'application/json, application/jwk-set+json' }, redirect: 'manual', signal: AbortSignal.timeout(FETCH_TIMEOUT) });
+    if (res.status !== 200) throw new Error();
+    jwks = JSON.parse(await res.text());
+  } catch { throw new Unreachable(); }
+  if (jwks === null || typeof jwks !== 'object' || !Array.isArray(jwks.keys)) throw new Refused();
+  const usable = p.algs.filter(alg => jwks.keys.some(k => usableKey(k, alg)));
+  if (!usable.length) throw new Refused();
+  return as;
+}
+
+// `config` is console.sso, checked again here; `secrets` maps provider id to its client secret
+// (readSlot). `fetch` is for tests: a fetch that trusts only the fake OP's certificate.
+// `retryFirst` is for tests too; production waits 5 s, doubling, capped at 5 minutes.
+export async function createSso(config, { secrets, fetch: customFetch = null, log = line => console.log(line), retryFirst = 5000 } = {}) {
+  checkConsole({ sso: config });
+  oauth ??= await import('oauth4webapi');
+  const publicOrigin = config.publicOrigin;
+  const publicHost = new URL(publicOrigin).host;
+  const redirectUri = `${publicOrigin}/auth/callback`;
+  const fetchOptions = customFetch ? { [oauth.customFetch]: customFetch } : {};
+  const sessions = new Map(), logins = new Map();
+  const timers = new Set();
+  let closed = false;
+  const refuse = (code, provider, extra = '') => {
+    if (!CODES.has(code)) throw new Error(`unknown sso log code ${code}`);
+    log(`${new Date().toISOString()} sso refused code=${code} provider=${provider}${extra}`);
+  };
+
+  const providers = new Map(config.providers.map(p => {
+    if (typeof secrets?.get(p.id) !== 'string') throw new Error(`console.sso provider ${p.id} has no client secret`);
+    return [p.id, {
+      config: p, state: 'unreachable', as: null, jwks: {},
+      client: { client_id: p.clientId, id_token_signed_response_alg: [...p.algs] },
+      auth: oauth.ClientSecretBasic(secrets.get(p.id)),
+      subjects: new Map(p.subjects.map(s => [s.sub, s.name])),
+    }];
+  }));
+
+  async function attempt(entry, atStart) {
+    try {
+      entry.as = await discover(entry.config, fetchOptions);
+      entry.jwks = {};
+      entry.state = 'ready';
+    } catch (err) {
+      if (err instanceof Refused) {
+        entry.state = 'refused';
+        refuse('discovery-failed', entry.config.id);
+        if (atStart) throw new Error(`console.sso provider ${entry.config.id} refused at discovery: the issuer, algorithms, S256 or JWKS check failed`);
+        return;
+      }
+      entry.state = 'unreachable';
+      refuse('discovery-failed', entry.config.id);
+      throw err;
+    }
+  }
+  function retry(entry, delay) {
+    if (closed) return;
+    const timer = setTimeout(async () => {
+      timers.delete(timer);
+      try { await attempt(entry, false); } catch { retry(entry, Math.min(delay * 2, RETRY_CAP)); }
+    }, delay);
+    timer.unref();
+    timers.add(timer);
+  }
+  for (const entry of providers.values()) {
+    try { await attempt(entry, true); } catch (err) {
+      if (!(err instanceof Unreachable)) throw err;
+      retry(entry, retryFirst);
+    }
+  }
+
+  const page = (res, status, title, html, headers = {}) => {
+    res.writeHead(status, { 'content-type': 'text/html; charset=utf-8', 'cache-control': 'no-store', ...headers });
+    res.end(`<!doctype html><meta charset="utf-8"><title>${escape(title)}</title><main style="font-family:sans-serif;max-width:32rem;margin:4rem auto"><h1>${escape(title)}</h1>${html}</main>\n`);
+  };
+  const redirect = (res, location, setCookie = []) => {
+    res.writeHead(303, { location, 'cache-control': 'no-store', ...(setCookie.length ? { 'set-cookie': setCookie } : {}) });
+    res.end();
+  };
+  const failed = (res, setCookie = []) => page(res, 403, 'Sign-in failed', '<p><a href="/auth/login">Sign in again</a></p>', setCookie.length ? { 'set-cookie': setCookie } : {});
+  const expire = name => `${name}=; ${ATTRS}; Max-Age=0`;
+  const remember = (map, key, value, cap) => {
+    while (map.size >= cap) map.delete(map.keys().next().value);
+    map.set(key, value);
+  };
+
+  // B2: only a URL on publicOrigin itself; anything else, or nothing, is publicOrigin's `/`. The
+  // Location is absolute and its origin checked again: dot segments can leave a pathname of `//host`,
+  // which as a relative Location a browser reads as another origin (webby-0019 B1, sage-1403).
+  function returnURL(ret) {
+    const home = `${publicOrigin}/`;
+    try {
+      if (typeof ret !== 'string' || !ret) return home;
+      const u = new URL(ret, publicOrigin);
+      if (u.origin !== publicOrigin) return home;
+      const out = new URL(`${publicOrigin}${u.pathname}${u.search}`);
+      return out.origin === publicOrigin ? out.href : home;
+    } catch { return home; }
+  }
+
+  async function start(res, entry, ret) {
+    const state = oauth.generateRandomState(), nonce = oauth.generateRandomNonce(), verifier = oauth.generateRandomCodeVerifier();
+    const challenge = await oauth.calculatePKCECodeChallenge(verifier);
+    const id = randomBytes(32).toString('base64url');
+    remember(logins, sha256(id), { provider: entry.config.id, state, nonce, verifier, ret: typeof ret === 'string' ? ret.slice(0, 2048) : '/', expires: Date.now() + LOGIN_MAX_AGE * 1000 }, MAX_LOGINS);
+    const url = new URL(entry.as.authorization_endpoint);
+    for (const [k, v] of Object.entries({ client_id: entry.config.clientId, response_type: 'code', scope: 'openid profile email', redirect_uri: redirectUri, state, nonce, code_challenge: challenge, code_challenge_method: 'S256' })) url.searchParams.set(k, v);
+    return redirect(res, url.href, [`${LOGIN_COOKIE}=${id}; ${ATTRS}; Max-Age=${LOGIN_MAX_AGE}`]);
+  }
+
+  function login(res, query) {
+    const asked = query.get('provider');
+    const ret = query.get('return');
+    if (asked === null && providers.size > 1) {
+      const items = [...providers.values()].map(e => `<li><a href="/auth/login?${escape(new URLSearchParams({ provider: e.config.id, ...(ret ? { return: ret } : {}) }))}">${escape(e.config.id)}</a></li>`).join('');
+      return page(res, 200, 'Sign in', `<ul>${items}</ul>`);
+    }
+    const entry = asked === null ? [...providers.values()][0] : providers.get(asked);
+    if (!entry) return page(res, 404, 'Unknown sign-in provider', '<p><a href="/auth/login">Sign in</a></p>');
+    if (entry.state !== 'ready') return page(res, 503, 'sign-in unavailable', '<p>The sign-in provider can\'t be reached. Try again shortly.</p>');
+    return start(res, entry, ret);
+  }
+
+  // Design section 1, steps 2-7. Each refusal ends here with one log line and the 403 page.
+  async function callback(res, query, req) {
+    const clear = [expire(LOGIN_COOKIE)];
+    const ids = cookies(req, LOGIN_COOKIE);
+    const key = ids.length === 1 ? sha256(ids[0]) : null;
+    const record = key === null ? undefined : logins.get(key);
+    if (key !== null) logins.delete(key);
+    // The provider comes from the record, never from the query.
+    const entry = record && providers.get(record.provider);
+    if (!record || record.expires <= Date.now() || !entry) {
+      refuse('login-record-missing', record?.provider ?? 'none');
+      return failed(res, clear);
+    }
+    const pid = entry.config.id;
+    if (entry.state !== 'ready') { refuse('discovery-failed', pid); return failed(res, clear); }
+    let params;
+    try { params = oauth.validateAuthResponse(entry.as, entry.client, query, record.state); } catch (err) {
+      refuse(err instanceof oauth.AuthorizationResponseError ? 'auth-error-response' : 'state-mismatch', pid);
+      return failed(res, clear);
+    }
+    const options = () => ({ ...fetchOptions, [oauth.jwksCache]: entry.jwks, signal: AbortSignal.timeout(FETCH_TIMEOUT) });
+    let response;
+    try { response = await oauth.authorizationCodeGrantRequest(entry.as, entry.client, entry.auth, params, redirectUri, record.verifier, options()); } catch {
+      refuse('grant-failed', pid); return failed(res, clear);
+    }
+    let result, claims;
+    try {
+      result = await oauth.processAuthorizationCodeResponse(entry.as, entry.client, response, { expectedNonce: record.nonce, requireIdToken: true });
+      claims = oauth.getValidatedIdTokenClaims(result);
+    } catch (err) {
+      refuse(err instanceof oauth.ResponseBodyError ? 'grant-failed' : 'id-token-invalid', pid);
+      return failed(res, clear);
+    }
+    // Step 5: the library skips this for a token-endpoint ID token; point 2 needs it, on the same
+    // Response object. Its throw ends the callback.
+    try { await oauth.validateApplicationLevelSignature(entry.as, response, options()); } catch (err) {
+      const fetching = !(err instanceof oauth.OperationProcessingError || err instanceof oauth.UnsupportedOperationError) || [oauth.RESPONSE_IS_NOT_CONFORM, oauth.RESPONSE_IS_NOT_JSON].includes(err.code);
+      refuse(fetching ? 'jwks-failed' : 'signature-invalid', pid);
+      return failed(res, clear);
+    }
+    // Step 6: our own checks on top of the library's.
+    let header;
+    try { header = JSON.parse(Buffer.from(result.id_token.split('.')[0], 'base64url').toString('utf8')); } catch { header = null; }
+    if (!header || !entry.config.algs.includes(header.alg)) { refuse('alg-refused', pid); return failed(res, clear); }
+    if (claims.iss !== entry.config.issuer) { refuse('issuer-mismatch', pid); return failed(res, clear); }
+    const name = typeof claims.sub === 'string' ? entry.subjects.get(claims.sub) : undefined;
+    if (name === undefined) {
+      refuse('subject-unknown', pid, ` iss=${JSON.stringify(String(claims.iss).slice(0, 255))} sub=${JSON.stringify(String(claims.sub).slice(0, 255))}`);
+      return failed(res, clear);
+    }
+    // Step 7: the session, then the return path.
+    const id = randomBytes(32).toString('base64url'), now = Date.now();
+    remember(sessions, sha256(id), { provider: pid, iss: claims.iss, sub: claims.sub, name, idToken: result.id_token, created: now, seen: now }, MAX_SESSIONS);
+    return redirect(res, returnURL(record.ret), [...clear, `${SESSION_COOKIE}=${id}; ${ATTRS}`]);
+  }
+
+  // The session for this request, or null. `touch` is true only for a page load or a write (Q-D).
+  function session(req, { touch = false } = {}) {
+    const ids = cookies(req, SESSION_COOKIE);
+    if (ids.length !== 1) return null;
+    const key = sha256(ids[0]);
+    const s = sessions.get(key);
+    if (!s) return null;
+    const now = Date.now();
+    if (now - s.created >= SESSION_ABSOLUTE || now - s.seen >= SESSION_IDLE) { sessions.delete(key); return null; }
+    if (touch) s.seen = now;
+    return s;
+  }
+
+  function logout(req, res) {
+    const one = name => (req.headersDistinct[name]?.length === 1 ? req.headersDistinct[name][0] : null);
+    if (one('origin') !== publicOrigin || one('sec-fetch-site') !== 'same-origin') {
+      return page(res, 403, 'Sign-out refused', '<p>Sign out from the Console page.</p>');
+    }
+    const ids = cookies(req, SESSION_COOKIE);
+    const key = ids.length === 1 ? sha256(ids[0]) : null;
+    const s = key === null ? undefined : sessions.get(key);
+    if (key !== null) sessions.delete(key);
+    const entry = s && providers.get(s.provider);
+    let location = `${publicOrigin}/auth/signed-out`;
+    if (entry?.as?.end_session_endpoint) {
+      const url = new URL(entry.as.end_session_endpoint);
+      url.searchParams.set('id_token_hint', s.idToken);
+      url.searchParams.set('post_logout_redirect_uri', `${publicOrigin}/auth/signed-out`);
+      url.searchParams.set('client_id', entry.config.clientId);
+      location = url.href;
+    }
+    return redirect(res, location, [expire(SESSION_COOKIE)]);
+  }
+
+  // `/auth/*` on the human listener; the caller has already checked the Host.
+  async function handle(req, res, path, search) {
+    const query = new URLSearchParams(search);
+    if (path === '/auth/logout') {
+      if (req.method !== 'POST') return page(res, 405, 'Method not allowed', '');
+      return logout(req, res);
+    }
+    if (req.method !== 'GET') return page(res, 405, 'Method not allowed', '');
+    if (path === '/auth/login') return login(res, query);
+    if (path === '/auth/callback') return callback(res, query, req);
+    if (path === '/auth/signed-out') return page(res, 200, 'Signed out', '<p><a href="/auth/login">Sign in</a></p>');
+    return page(res, 404, 'Not found', '');
+  }
+
+  return {
+    publicOrigin, publicHost, sessions, logins, handle, session, returnURL,
+    health: () => Object.fromEntries([...providers].map(([id, e]) => [id, e.state])),
+    formTargets: () => [...new Set([...providers.values()].filter(e => e.as?.end_session_endpoint).map(e => new URL(e.as.end_session_endpoint).origin))],
+    summary: () => config.providers.map(p => ({ id: p.id, issuer: p.issuer, subjects: p.subjects.length })),
+    close() { closed = true; for (const t of timers) clearTimeout(t); timers.clear(); },
+  };
+}
@@ -0,0 +1,155 @@
+// Q175 phase 1 (#1690, design section 9): a fake OpenID provider for the --sso tests. A loopback
+// https server with a self-signed certificate made in a temp dir; `op.fetch` is a fetch that trusts
+// only that certificate, so the code under test needs no insecure flag. It serves any number of
+// issuers (`/<name>/`) at once, each with discovery, a JWKS, authorization, token and end-session
+// endpoints. Keys come from node:crypto. Nothing here reaches any other host.
+import { constants, createHash, createHmac, generateKeyPairSync, randomBytes, sign } from 'node:crypto';
+import { spawnSync } from 'node:child_process';
+import { mkdtempSync, readFileSync, rmSync } from 'node:fs';
+import { createServer, request } from 'node:https';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+export const b64url = value => Buffer.from(typeof value === 'string' ? value : JSON.stringify(value)).toString('base64url');
+
+export function rsaKey(kid = `rsa-${randomBytes(4).toString('hex')}`, bits = 2048) {
+  const { privateKey, publicKey } = generateKeyPairSync('rsa', { modulusLength: bits });
+  return { kid, alg: 'RS256', privateKey, jwk: { ...publicKey.export({ format: 'jwk' }), kid, use: 'sig', alg: 'RS256' } };
+}
+export function ecKey(kid = `ec-${randomBytes(4).toString('hex')}`) {
+  const { privateKey, publicKey } = generateKeyPairSync('ec', { namedCurve: 'P-256' });
+  return { kid, alg: 'ES256', privateKey, jwk: { ...publicKey.export({ format: 'jwk' }), kid, use: 'sig', alg: 'ES256' } };
+}
+export function psKey(kid = `ps-${randomBytes(4).toString('hex')}`) {
+  const k = rsaKey(kid);
+  return { ...k, alg: 'PS256', jwk: { ...k.jwk, alg: 'PS256' } };
+}
+
+// A compact JWS. `alg` HS256 uses `hmac` as the key, `none` has an empty signature.
+export function jwt(header, payload, { key = null, hmac = null } = {}) {
+  const input = `${b64url(header)}.${b64url(payload)}`;
+  let sig = '';
+  if (header.alg === 'HS256') sig = createHmac('sha256', hmac).update(input).digest('base64url');
+  else if (header.alg === 'RS256') sig = sign('sha256', Buffer.from(input), key).toString('base64url');
+  else if (header.alg === 'PS256') sig = sign('sha256', Buffer.from(input), { key, padding: constants.RSA_PKCS1_PSS_PADDING, saltLength: 32 }).toString('base64url');
+  else if (header.alg === 'ES256') sig = sign('sha256', Buffer.from(input), { key, dsaEncoding: 'ieee-p1363' }).toString('base64url');
+  return `${input}.${sig}`;
+}
+
+function certificate() {
+  const dir = mkdtempSync(join(tmpdir(), 'fake-oidc-'));
+  try {
+    const r = spawnSync('openssl', ['req', '-x509', '-newkey', 'ec', '-pkeyopt', 'ec_paramgen_curve:P-256', '-nodes', '-days', '1',
+      '-subj', '/CN=127.0.0.1', '-addext', 'subjectAltName=IP:127.0.0.1', '-keyout', join(dir, 'key.pem'), '-out', join(dir, 'cert.pem')], { encoding: 'utf8' });
+    if (r.status !== 0) throw new Error(`openssl failed: ${r.stderr}`);
+    return { key: readFileSync(join(dir, 'key.pem')), cert: readFileSync(join(dir, 'cert.pem')) };
+  } finally { rmSync(dir, { recursive: true, force: true }); }
+}
+
+// One issuer's state. `discovery` is merged over the defaults; `mode` is 'ok', 'down' (the socket is
+// destroyed) or 'html' (200 with an HTML page) for discovery.
+function issuerState(name, base, opts) {
+  const keys = opts.keys ?? [rsaKey()];
+  return {
+    name, issuer: `${base}/${name}/`, keys, retired: [], clientId: opts.clientId ?? `client-${name}`, clientSecret: opts.clientSecret ?? `secret-${name}-${randomBytes(6).toString('hex')}`,
+    discovery: opts.discovery ?? {}, mode: 'ok', jwksOverride: null, codes: new Map(), acceptTwice: false, requirePkce: true,
+    tokenRequests: [], authorizeRequests: [], jwksFetches: 0, discoveryFetches: 0,
+  };
+}
+
+export async function fakeOidc() {
+  const { key, cert } = certificate();
+  const issuers = new Map();
+  const server = createServer({ key, cert }, (req, res) => {
+    const url = new URL(req.url, 'https://127.0.0.1');
+    const [, name, ...rest] = url.pathname.split('/');
+    const iss = issuers.get(name);
+    const route = rest.join('/');
+    const json = (status, body, type = 'application/json') => { res.writeHead(status, { 'content-type': type }); res.end(typeof body === 'string' ? body : JSON.stringify(body)); };
+    if (!iss) return json(404, { error: 'no issuer' });
+    if (route === '.well-known/openid-configuration') {
+      iss.discoveryFetches++;
+      if (iss.mode === 'down') return req.socket.destroy();
+      if (iss.mode === 'html') return json(200, '<!doctype html><title>Sign in</title>', 'text/html');
+      return json(200, discovery(iss));
+    }
+    if (route === 'jwks') {
+      iss.jwksFetches++;
+      return json(200, iss.jwksOverride ?? { keys: iss.keys.map(k => k.jwk) });
+    }
+    if (route === 'authorize') { iss.authorizeRequests.push(Object.fromEntries(url.searchParams)); return json(200, { ok: true }); }
+    if (route === 'end-session') return json(200, { ok: true });
+    if (route === 'token' && req.method === 'POST') {
+      let text = '';
+      req.on('data', c => (text += c));
+      req.on('end', () => {
+        const form = new URLSearchParams(text);
+        const basic = Buffer.from((req.headers.authorization ?? '').replace(/^Basic /, ''), 'base64').toString();
+        const [id, secret] = basic.split(':').map(decodeURIComponent);
+        iss.tokenRequests.push({ form: Object.fromEntries(form), clientId: id });
+        if (id !== iss.clientId || secret !== iss.clientSecret) return json(401, { error: 'invalid_client' });
+        const grant = iss.codes.get(form.get('code'));
+        if (!grant) return json(400, { error: 'invalid_grant' });
+        if (!iss.acceptTwice) iss.codes.delete(form.get('code'));
+        if (form.get('redirect_uri') !== grant.redirectUri) return json(400, { error: 'invalid_grant', error_description: 'redirect_uri' });
+        if (iss.requirePkce && createHash('sha256').update(form.get('code_verifier') ?? '').digest('base64url') !== grant.challenge) return json(400, { error: 'invalid_grant', error_description: 'pkce' });
+        return json(200, { access_token: randomBytes(16).toString('hex'), token_type: 'Bearer', expires_in: 300, id_token: grant.idToken });
+      });
+      return;
+    }
+    return json(404, { error: 'not found' });
+  });
+  await new Promise(r => server.listen(0, '127.0.0.1', r));
+  const base = `https://127.0.0.1:${server.address().port}`;
+
+  const discovery = iss => ({
+    issuer: iss.issuer, authorization_endpoint: `${iss.issuer}authorize`, token_endpoint: `${iss.issuer}token`, jwks_uri: `${iss.issuer}jwks`,
+    end_session_endpoint: `${iss.issuer}end-session`, response_types_supported: ['code'], subject_types_supported: ['public'],
+    id_token_signing_alg_values_supported: [...new Set(iss.keys.map(k => k.alg))], code_challenge_methods_supported: ['S256'],
+    ...iss.discovery,
+  });
+
+  // A fetch over node:https that trusts only this certificate. oauth4webapi passes a Headers object
+  // and a string or URLSearchParams body.
+  const opFetch = (input, init = {}) => new Promise((resolve, reject) => {
+    const url = new URL(typeof input === 'string' ? input : input.href ?? input.url);
+    if (url.protocol !== 'https:' || url.hostname !== '127.0.0.1' || url.port !== String(server.address().port)) return reject(new TypeError(`fake OP fetch refuses ${url.origin}`));
+    const headers = Object.fromEntries(new Headers(init.headers ?? {}));
+    const body = init.body === undefined || init.body === null ? undefined : String(init.body);
+    if (body !== undefined) headers['content-length'] = Buffer.byteLength(body);
+    const req = request(url, { method: init.method ?? 'GET', headers, ca: cert, signal: init.signal }, res => {
+      const chunks = [];
+      res.on('data', c => chunks.push(c));
+      res.on('end', () => {
+        const h = new Headers();
+        for (const [k, v] of Object.entries(res.headers)) h.set(k, Array.isArray(v) ? v.join(', ') : v);
+        const response = new Response(res.statusCode === 204 ? null : Buffer.concat(chunks), { status: res.statusCode, headers: h });
+        Object.defineProperty(response, 'url', { value: url.href });
+        resolve(response);
+      });
+      res.on('error', reject);
+    });
+    req.on('error', reject);
+    req.end(body);
+  });
+
+  return {
+    base, fetch: opFetch, cert,
+    issuer(name, opts = {}) { const iss = issuerState(name, base, opts); issuers.set(name, iss); return iss; },
+    // A code for `iss` whose ID token is built from the start redirect's nonce, the claims and header
+    // overrides. `challenge` defaults to the start redirect's; `idToken` replaces the token outright.
+    grant(iss, authorizeUrl, { sub = `user-${iss.name}`, claims = {}, header = {}, key = iss.keys[0], idToken = null, challenge = null, redirectUri = null } = {}) {
+      const q = new URL(authorizeUrl).searchParams;
+      const now = Math.floor(Date.now() / 1000);
+      const payload = { iss: iss.issuer, sub, aud: iss.clientId, iat: now, exp: now + 300, nonce: q.get('nonce'), ...claims };
+      for (const [k, v] of Object.entries(payload)) if (v === undefined) delete payload[k];
+      const token = idToken ?? jwt({ alg: key.alg, kid: key.kid, typ: 'JWT', ...header }, payload, { key: key.privateKey, hmac: iss.clientSecret });
+      const code = randomBytes(12).toString('base64url');
+      iss.codes.set(code, { idToken: token, challenge: challenge ?? q.get('code_challenge'), redirectUri: redirectUri ?? q.get('redirect_uri') });
+      return { code, idToken: token, payload };
+    },
+    rotate(iss, next = rsaKey()) { iss.retired.push(...iss.keys); iss.keys = [next]; return next; },
+    close: () => new Promise(r => { server.close(r); server.closeAllConnections(); }),
+  };
+}
+
@@ -30,7 +30,7 @@ function fakeCopy(dir) {
  writeFileSync(join(copyRoot(dir), 'packages', 'webui', 'src', 'cli.mjs'), '');
  return copyRoot(dir);
 }
-const SEND_REFUSAL = /^webui-service: --send needs the preview mode \(--public-host, --auth-header and --allow-user\)$/m;
+const SEND_REFUSAL = /^webui-service: --send needs the preview mode \(--public-host, --auth-header and --allow-user\) or --sso$/m;
 const TEMPLATE = readFileSync(join(REPO, 'packages', 'webui', 'systemd', 'mosaic-webui.service.in'), 'utf8');

 // The unit as the base script renders it (row 75): the template with its four
@@ -0,0 +1,132 @@
+// Q175 phase 1 (#1690, design test 24, sage-1340 F1, sage-1347 F7): the page under --sso. A read
+// the Console answers 401 `sign-in required` signs the page out the way a proxy redirect does, and
+// the line links to /auth/login with the current path and query; any other 401 stays an error. Both
+// fetch paths in app.js and both in bus.js (fetchRead and fetchApi) do it. The Sign out form shows
+// only when /api/config says sso. The board-held.test.mjs stub, with two lists of paths: those in
+// window.__signIn answer 401 `sign-in required`, those in window.__other 401 `unauthenticated`. A
+// page URL holding `sso` gets `sso: true` added to /api/config. Poll timers fire after 150 ms.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { Store } from '../../bus/src/store.mjs';
+import { Broker } from '../../bus/src/broker.mjs';
+import { views } from '../../bus/src/views.mjs';
+import { startServer } from '../src/serve.mjs';
+import { browser } from './browser.mjs';
+import { fixture, close } from './fixture.mjs';
+
+const businesses = { demo: { id: 'demo', human: 'jason', arbiters: { technical: 'cto', delivery: 'pm' }, roles: { pm: { authority: { withinRole: ['message.send'], crossRole: [] } }, cto: { authority: { withinRole: ['message.send'], crossRole: [] } } } } };
+
+const stub = `(() => {
+  const real = window.fetch.bind(window);
+  window.__reqs = []; window.__signIn = []; window.__other = [];
+  const timeout = window.setTimeout.bind(window);
+  window.setTimeout = (f, ms, ...rest) => timeout(f, ms === 10000 ? 150 : ms, ...rest);
+  const answer = (status, body) => new Response(JSON.stringify(body), { status, headers: { 'content-type': 'application/json' } });
+  window.fetch = async (url, init = {}) => {
+    const path = String(url).split('?')[0];
+    window.__reqs.push(path);
+    if (window.__signIn.includes(path)) return answer(401, { error: 'sign-in required' });
+    if (window.__other.includes(path)) return answer(401, { error: 'unauthenticated' });
+    if (path === '/api/config' && /sso/.test(location.search)) return answer(200, { ...(await (await real(url, init)).json()), sso: true });
+    return real(url, init);
+  };
+})();`;
+
+async function setup() {
+  const root = mkdtempSync(join(tmpdir(), 'webui-sso-browser-'));
+  const store = new Store(root), b0 = new Broker({ store, businesses });
+  b0.request(b0.bindLaunch({ business: 'demo', role: 'pm', run: 'pm-run', harness: 'pi', address: 'pm-run' }), { verb: 'role.claim' });
+  const reader = b0.bindReader({ business: 'demo' });
+  const bus = views({ call: async (verb, args = {}) => structuredClone(b0.request(reader, { verb, args })) });
+  const f = await fixture(), b = await browser({ machine: true });
+  const web = await startServer({ port: 0, board: f.boardURL, bus }), base = `http://127.0.0.1:${web.address().port}/`;
+  await b.call('Page.addScriptToEvaluateOnNewDocument', { source: stub });
+  await b.viewport(1280);
+  const wait = expr => b.evaluate(`(async()=>{for(let i=0;i<100;i++){if(${expr})return true;await new Promise(r=>setTimeout(r,50))}throw new Error('Condition timed out: '+${JSON.stringify(expr)})})()`);
+  const text = sel => b.evaluate(`document.querySelector(${JSON.stringify(sel)})?.textContent ?? null`);
+  const shown = sel => b.evaluate(`(()=>{const e=document.querySelector(${JSON.stringify(sel)});return !!e && !e.hidden && getComputedStyle(e).display !== 'none' && !!e.getClientRects().length})()`);
+  const reqs = () => b.evaluate('window.__reqs.length');
+  const settle = () => new Promise(r => setTimeout(r, 600));
+  const done = async () => { await b.close(); await close(web); await f.close(); store.close(); rmSync(root, { recursive: true, force: true }); };
+  return { b, base, wait, text, shown, reqs, settle, done };
+}
+
+const LOADED = 'document.querySelector("table.sessions [data-open=\'proj/agent1\']")';
+const LINE = 'Signed out. Sign in again.';
+
+test('a 401 sign-in required on each fetch path signs the page out with a sign-in link and stops the refresh; another 401 stays an error', { timeout: 120000 }, async () => {
+  const { b, base, wait, text, shown, reqs, settle, done } = await setup();
+  // The line, its link back to this page, the Sign out form gone, and no further fetch.
+  const out = async ret => {
+    await wait('!document.querySelector("#signed-out").hidden');
+    assert.equal(await text('#signed-out'), LINE);
+    assert.equal(await b.evaluate('document.querySelector("#signed-out a").getAttribute("href")'), `/auth/login?return=${encodeURIComponent(ret)}`);
+    assert.equal(await shown('#sign-out'), false);
+    assert.equal(await b.evaluate('document.querySelector("#refresh").disabled'), true);
+    const n = await reqs();
+    await b.evaluate('document.querySelector("#refresh").click(), true');
+    await settle();
+    assert.equal(await reqs(), n, 'the page fetched after signing out');
+  };
+  try {
+    // app.js api(): the Board read, with sso on from /api/config.
+    await b.navigate(`${base}?sso&x=1`);
+    await wait(LOADED);
+    await b.evaluate(`window.__signIn.push('/api/board'), document.querySelector('#refresh').click(), true`);
+    await out('/?sso&x=1');
+
+    // app.js getJSON: the conversation catalogue behind History.
+    await b.navigate(`${base}?sso&conv`);
+    await wait(LOADED);
+    await b.evaluate(`window.__signIn.push('/api/conversations'), document.querySelector('table.sessions [data-history="proj/agent1"]').click(), true`);
+    await out('/?sso&conv');
+
+    // app.js api(): the board POST behind Seen.
+    await b.navigate(`${base}?sso&seen`);
+    await wait(LOADED);
+    await b.evaluate(`document.querySelector('table.sessions [data-open="proj/agent1"]').click(), true`);
+    await wait('document.querySelector("#inspection [data-seen]")');
+    await b.evaluate(`window.__signIn.push('/api/seen'), document.querySelector('#inspection [data-seen]').click(), true`);
+    await out('/?sso&seen');
+
+    // bus.js fetchRead and fetchApi, on a page whose /api/config has no sso: the link comes from
+    // the 401 itself (F1).
+    await b.navigate(`${base}?read#/inbox`);
+    await wait(LOADED);
+    await b.evaluate(`window.__signIn.push('/api/bus/inbox'), document.querySelector('#refresh').click(), true`);
+    await out('/?read');
+    await b.navigate(`${base}?module`);
+    await wait(LOADED);
+    await b.evaluate(`window.__signIn.push('/api/queue'), location.hash = '#/queue', true`);
+    await out('/?module');
+
+    // Any other 401 is an error: no sign-out, and the polls go on.
+    await b.navigate(`${base}?sso&other`);
+    await wait(LOADED);
+    await b.evaluate(`window.__other.push('/api/board', '/api/bus/inbox', '/api/queue'), document.querySelector('#refresh').click(), true`);
+    await settle();
+    assert.equal(await b.evaluate('document.querySelector("#signed-out").hidden'), true);
+    assert.equal(await b.evaluate('document.body.classList.contains("signed-out")'), false);
+    const n = await reqs();
+    await settle();
+    assert.ok(await reqs() > n, 'the refresh stopped on another 401');
+    assert.equal(await shown('#sign-out'), true);
+  } finally { await done(); }
+});
+
+test('the Sign out form shows only when /api/config says sso, and posts to /auth/logout', { timeout: 120000 }, async () => {
+  const { b, base, wait, shown, done } = await setup();
+  try {
+    await b.navigate(base);
+    await wait(LOADED);
+    await new Promise(r => setTimeout(r, 300));
+    assert.equal(await shown('#sign-out'), false);
+    await b.navigate(`${base}?sso`);
+    await wait(`${LOADED} && !document.querySelector("#sign-out").hidden`);
+    assert.equal(await shown('#sign-out'), true);
+    assert.deepEqual(await b.evaluate('(() => { const f = document.querySelector("#sign-out"); return [f.method, f.getAttribute("action"), f.querySelector("button").textContent, f.querySelector("button").type]; })()'), ['post', '/auth/logout', 'Sign out', 'submit']);
+  } finally { await done(); }
+});
@@ -0,0 +1,589 @@
+// Q175 phase 1 (#1690, design agents/sage/work/q175-sso/DESIGN.md section 9): the Console as an
+// OIDC relying party (--sso). Every provider is the fake OP in helpers/fake-oidc.mjs on loopback;
+// no test reaches a real provider, the live Console or a real config or slot file. The public name
+// is console.example.test, sent only as a Host header to the test's own loopback listener. Each
+// refusal checks the status, that no session cookie was set and that the send stub never ran.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { request } from 'node:http';
+import { spawn, spawnSync } from 'node:child_process';
+import { chmodSync, mkdirSync, mkdtempSync, rmSync, symlinkSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { startServer } from '../src/serve.mjs';
+import { createSso, readSlot, SESSION_COOKIE, LOGIN_COOKIE } from '../src/sso.mjs';
+import { close } from './fixture.mjs';
+import { b64url, ecKey, fakeOidc, jwt, psKey, rsaKey } from './helpers/fake-oidc.mjs';
+
+const HOST = 'console.example.test', ORIGIN = `https://${HOST}`;
+const CLI = fileURLToPath(new URL('../src/cli.mjs', import.meta.url));
+const MSG = JSON.stringify({ to: 'coder', body: 'Please look at row 192.' });
+// Test 19: every log line any test here captured, and every token, code, state, nonce, verifier,
+// client secret and session id any test produced. The last test checks the one against the other.
+const ALL_LINES = [], PRODUCED = new Set();
+
+// node:http, not fetch: fetch can't set Host, Origin or Sec-Fetch-Site.
+function call(port, { method = 'GET', path = '/', headers = {}, body, host = HOST } = {}) {
+  return new Promise((resolve, reject) => {
+    const length = body === undefined ? {} : { 'content-length': Buffer.byteLength(body) };
+    const req = request({ host: '127.0.0.1', port, method, path, headers: { host, ...length, ...headers } }, res => {
+      let text = '';
+      res.on('data', c => (text += c));
+      res.on('end', () => resolve({ status: res.statusCode, headers: res.headers, body: text && (res.headers['content-type'] ?? '').startsWith('application/json') ? JSON.parse(text) : text }));
+    });
+    req.on('error', reject);
+    req.end(body);
+  });
+}
+const setCookies = r => [r.headers['set-cookie'] ?? []].flat();
+const sessionOf = r => setCookies(r).find(c => c.startsWith(`${SESSION_COOKIE}=`) && !c.includes('Max-Age=0'))?.split(';')[0] ?? null;
+const writeHeaders = cookie => ({ ...(cookie ? { cookie } : {}), origin: ORIGIN, 'sec-fetch-site': 'same-origin', 'content-type': 'application/json' });
+
+function providerFor(iss, extra = {}) {
+  return { id: iss.name, issuer: iss.issuer, clientId: iss.clientId, clientSecret: { slot: iss.name }, algs: [...new Set(iss.keys.map(k => k.alg))], subjects: [{ sub: `user-${iss.name}`, name: `person-${iss.name}` }], ...extra };
+}
+
+// A fake OP with `issuers`, createSso over them, and the human listener with a counting send.
+async function setup(t, { issuers = [{ name: 'a' }], provider = {}, before = null, retryFirst = 5000, server = {} } = {}) {
+  const op = await fakeOidc();
+  t.after(() => op.close());
+  const iss = issuers.map(o => op.issuer(o.name, o));
+  for (const i of iss) PRODUCED.add(i.clientSecret);
+  before?.(op, iss);
+  const config = { publicOrigin: ORIGIN, providers: iss.map(i => providerFor(i, provider[i.name] ?? {})) };
+  const lines = [];
+  const log = line => { lines.push(line); ALL_LINES.push(line); };
+  const sso = await createSso(config, { secrets: new Map(iss.map(i => [i.name, i.clientSecret])), fetch: op.fetch, log, retryFirst });
+  t.after(() => sso.close());
+  const sends = [];
+  const bus = Object.fromEntries(['inbox', 'tasks', 'agents', 'trail', 'decisions'].map(v => [v, async () => [{ verb: v }]]));
+  const web = await startServer({ port: 0, board: 'http://127.0.0.1:9', bus, sso, send: async args => { sends.push(args); return { id: 'msg-0001' }; }, log, ...server });
+  t.after(() => close(web));
+  return { op, iss, sso, port: web.address().port, lines, sends, config, bus };
+}
+
+// GET /auth/login; returns the authorize URL and the login cookie (name=value).
+async function begin(env, { provider = null, ret = null, query = null, host = HOST } = {}) {
+  const q = query ?? new URLSearchParams({ ...(provider ? { provider } : {}), ...(ret !== null ? { return: ret } : {}) }).toString();
+  const r = await call(env.port, { path: `/auth/login${q ? `?${q}` : ''}`, host });
+  assert.equal(r.status, 303, `login start: ${r.status} ${r.body}`);
+  const cookie = setCookies(r)[0].split(';')[0];
+  const location = r.headers.location;
+  const params = new URL(location).searchParams;
+  PRODUCED.add(cookie.split('=')[1]);
+  for (const k of ['state', 'nonce', 'code_challenge']) PRODUCED.add(params.get(k));
+  for (const record of env.sso.logins.values()) PRODUCED.add(record.verifier);
+  return { r, cookie, location, params };
+}
+function callback(env, begun, { code, state = begun.params.get('state'), extra = {}, cookie = begun.cookie } = {}) {
+  const q = new URLSearchParams({ ...(code !== undefined ? { code } : {}), state, ...extra });
+  return call(env.port, { path: `/auth/callback?${q}`, headers: cookie ? { cookie } : {} });
+}
+function grant(env, begun, iss, opts = {}) {
+  const g = env.op.grant(iss, begun.location, opts);
+  PRODUCED.add(g.code);
+  PRODUCED.add(g.idToken);
+  return g;
+}
+// A whole sign-in: start, a code at the OP, the callback. Returns the callback answer and the
+// session cookie (name=value) when one was set.
+async function signIn(env, { iss = env.iss[0], ret = null, opts = {} } = {}) {
+  const begun = await begin(env, { provider: env.iss.length > 1 ? iss.name : null, ret });
+  const g = grant(env, begun, iss, opts);
+  const r = await callback(env, begun, { code: g.code });
+  const session = sessionOf(r);
+  if (session) PRODUCED.add(session.split('=')[1]);
+  return { begun, g, r, session };
+}
+function refused(env, r, code) {
+  assert.equal(r.status, 403, `expected 403, got ${r.status}`);
+  assert.equal(sessionOf(r), null, 'a session cookie was set');
+  assert.equal(env.sends.length, 0, 'the send stub ran');
+  assert.ok(setCookies(r).includes(`${LOGIN_COOKIE}=; Path=/; Secure; HttpOnly; SameSite=Lax; Max-Age=0`), 'the login cookie was not expired');
+  if (code) assert.match(env.lines.at(-1), new RegExp(` sso refused code=${code} provider=`), env.lines.at(-1));
+}
+
+test('positive: an RS256 provider signs in and sends one message, and the session reads', async t => {
+  const env = await setup(t);
+  assert.notEqual(env.port, 7332);
+  const { r, session } = await signIn(env, { ret: '/board?x=1' });
+  assert.equal(r.status, 303);
+  assert.equal(r.headers.location, `${ORIGIN}/board?x=1`);
+  assert.ok(session);
+  const send = await call(env.port, { method: 'POST', path: '/api/bus/message', headers: writeHeaders(session), body: MSG });
+  assert.equal(send.status, 200, JSON.stringify(send.body));
+  assert.deepEqual(env.sends, [{ to: 'coder', body: 'Please look at row 192.' }]);
+  assert.match(env.lines.at(-1), / send user="person-a" to="coder" id=msg-0001$/);
+  const read = await call(env.port, { path: '/api/bus/inbox', headers: { cookie: session } });
+  assert.equal(read.status, 200);
+  const config = await call(env.port, { path: '/api/config', headers: { cookie: session } });
+  assert.equal(config.body.sso, true);
+  assert.equal(config.body.send, true);
+});
+
+test('positive: an ES256 provider signs in and sends', async t => {
+  const env = await setup(t, { issuers: [{ name: 'e', keys: [ecKey()] }] });
+  assert.deepEqual(env.config.providers[0].algs, ['ES256']);
+  const { session } = await signIn(env);
+  assert.ok(session);
+  assert.equal((await call(env.port, { method: 'POST', path: '/api/bus/message', headers: writeHeaders(session), body: MSG })).status, 200);
+  assert.equal(env.sends.length, 1);
+});
+
+test('positive: two providers each sign in their own subjects, and one provider\'s subject is unknown to the other', async t => {
+  const env = await setup(t, { issuers: [{ name: 'a' }, { name: 'b', keys: [ecKey()] }] });
+  const list = await call(env.port, { path: '/auth/login?return=%2Fboard' });
+  assert.equal(list.status, 200);
+  assert.match(list.body, /provider=a&#38;return=%2Fboard/);
+  assert.match(list.body, /provider=b&#38;return=%2Fboard/);
+  const [a, b] = env.iss;
+  assert.ok((await signIn(env, { iss: a })).session);
+  assert.ok((await signIn(env, { iss: b })).session);
+  const names = [...env.sso.sessions.values()].map(s => s.name);
+  assert.deepEqual(names, ['person-a', 'person-b']);
+  const cross = await signIn(env, { iss: b, opts: { sub: 'user-a' } });
+  refused({ ...env, sends: [] }, cross.r, 'subject-unknown');
+});
+
+test('1: a forged x-authentik header without a cookie is 401 on the API and a sign-in redirect on a page', async t => {
+  const env = await setup(t);
+  const forged = { 'x-authentik-username': 'jason.woltje', origin: ORIGIN, 'sec-fetch-site': 'same-origin', 'content-type': 'application/json' };
+  for (const [method, path, body] of [['POST', '/api/bus/message', MSG], ['POST', '/api/settings', '{}'], ['GET', '/api/config', undefined]]) {
+    const r = await call(env.port, { method, path, headers: forged, body });
+    assert.equal(r.status, 401, `${method} ${path}`);
+    assert.deepEqual(r.body, { error: 'sign-in required' });
+  }
+  const page = await call(env.port, { path: '/', headers: forged });
+  assert.equal(page.status, 303);
+  assert.equal(page.headers.location, '/auth/login?return=%2F');
+  const deep = await call(env.port, { path: '/board?x=1' });
+  assert.equal(deep.headers.location, '/auth/login?return=%2Fboard%3Fx%3D1');
+  assert.equal(env.sends.length, 0);
+});
+
+test('2: an HS256 ID token keyed with the client secret and a real RSA kid is refused', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  const { r } = await signIn(env, { opts: { header: { alg: 'HS256', kid: iss.keys[0].kid } } });
+  refused(env, r, 'id-token-invalid');
+});
+
+test('3: a wrong aud, and an aud list holding another client with no azp, are refused', async t => {
+  const env = await setup(t);
+  refused(env, (await signIn(env, { opts: { claims: { aud: 'another-client' } } })).r, 'id-token-invalid');
+  refused(env, (await signIn(env, { opts: { claims: { aud: [env.iss[0].clientId, 'another-client'] } } })).r, 'id-token-invalid');
+});
+
+test('4: a token that expired 10 minutes ago is refused', async t => {
+  const env = await setup(t);
+  const now = Math.floor(Date.now() / 1000);
+  refused(env, (await signIn(env, { opts: { claims: { iat: now - 900, exp: now - 600 } } })).r, 'id-token-invalid');
+});
+
+test('5: another issuer, and the issuer without its trailing slash, are refused', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  refused(env, (await signIn(env, { opts: { claims: { iss: `${env.op.base}/other/` } } })).r, 'id-token-invalid');
+  refused(env, (await signIn(env, { opts: { claims: { iss: iss.issuer.slice(0, -1) } } })).r, 'id-token-invalid');
+});
+
+test('6: a nonce mismatch and a missing nonce are refused', async t => {
+  const env = await setup(t);
+  refused(env, (await signIn(env, { opts: { claims: { nonce: 'not-the-nonce' } } })).r, 'id-token-invalid');
+  refused(env, (await signIn(env, { opts: { claims: { nonce: undefined } } })).r, 'id-token-invalid');
+});
+
+test('7: state mismatch, no login cookie, a replay, an expired record and two login cookies are refused', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  let begun = await begin(env);
+  refused(env, await callback(env, begun, { code: grant(env, begun, iss).code, state: 'wrong-state' }), 'state-mismatch');
+  begun = await begin(env);
+  refused(env, await callback(env, begun, { code: grant(env, begun, iss).code, cookie: null }), 'login-record-missing');
+  // Replay: the OP takes the code twice, so only the take-and-delete rule refuses the second callback.
+  iss.acceptTwice = true;
+  begun = await begin(env);
+  const g = grant(env, begun, iss);
+  const first = await callback(env, begun, { code: g.code });
+  assert.equal(first.status, 303);
+  PRODUCED.add(sessionOf(first).split('=')[1]);
+  refused(env, await callback(env, begun, { code: g.code }), 'login-record-missing');
+  iss.acceptTwice = false;
+  begun = await begin(env);
+  for (const record of env.sso.logins.values()) record.expires = Date.now() - 1;
+  refused(env, await callback(env, begun, { code: grant(env, begun, iss).code }), 'login-record-missing');
+  begun = await begin(env);
+  const other = await begin(env);
+  refused(env, await callback(env, begun, { code: grant(env, begun, iss).code, cookie: `${begun.cookie}; ${other.cookie}` }), 'login-record-missing');
+});
+
+test('8: the token request carries the PKCE verifier, and the OP refuses a wrong one', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  const { r, begun } = await signIn(env);
+  assert.equal(r.status, 303);
+  const { form } = iss.tokenRequests.at(-1);
+  assert.equal(begun.params.get('code_challenge_method'), 'S256');
+  const { createHash } = await import('node:crypto');
+  assert.equal(createHash('sha256').update(form.code_verifier).digest('base64url'), begun.params.get('code_challenge'));
+  refused(env, (await signIn(env, { opts: { challenge: 'not-the-challenge' } })).r, 'grant-failed');
+});
+
+test('9: alg none, a changed payload under a real kid, and an unknown kid even after the refetch are refused', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  // (a) alg none: the alg rule, before any signature check.
+  refused(env, (await signIn(env, { opts: { header: { alg: 'none' } } })).r, 'id-token-invalid');
+  // (b) a real kid's signature over another payload: only the signature check catches it.
+  let begun = await begin(env);
+  const real = env.op.grant(iss, begun.location);
+  PRODUCED.add(real.idToken);
+  const [h, , s] = real.idToken.split('.');
+  const forged = `${h}.${b64url({ ...real.payload, name: 'changed' })}.${s}`;
+  refused(env, await callback(env, begun, { code: grant(env, begun, iss, { idToken: forged }).code }), 'signature-invalid');
+  // (c) a key the JWKS never held, again after the cache is old enough to refetch.
+  t.mock.timers.enable({ apis: ['Date'], now: Date.now() });
+  const stranger = rsaKey('not-in-jwks');
+  refused(env, (await signIn(env, { opts: { key: stranger } })).r, 'signature-invalid');
+  const fetches = iss.jwksFetches;
+  t.mock.timers.tick(61000);
+  refused(env, (await signIn(env, { opts: { key: stranger } })).r, 'signature-invalid');
+  assert.equal(iss.jwksFetches, fetches + 1, 'no refetch');
+});
+
+test('10: a valid token for a subject not configured is 403 with one subject-unknown line', async t => {
+  const env = await setup(t);
+  const before = env.lines.length;
+  const { r } = await signIn(env, { opts: { sub: 'stranger' } });
+  refused(env, r, 'subject-unknown');
+  const added = env.lines.slice(before);
+  assert.equal(added.length, 1);
+  assert.match(added[0], new RegExp(`^\\S+ sso refused code=subject-unknown provider=a iss=${JSON.stringify(env.iss[0].issuer).replace(/[.*+?^${}()|[\]\\/]/g, '\\$&')} sub="stranger"$`));
+});
+
+test('11: start refusals: HS or none algs, reserved names, HS-only discovery, an empty JWKS, no S256, an issuer mismatch, a short RSA key', async t => {
+  const op = await fakeOidc();
+  t.after(() => op.close());
+  const start = (iss, extra = {}) => createSso({ publicOrigin: ORIGIN, providers: [providerFor(iss, extra)] }, { secrets: new Map([[iss.name, iss.clientSecret]]), fetch: op.fetch, log: l => ALL_LINES.push(l) });
+  const a = op.issuer('a');
+  PRODUCED.add(a.clientSecret);
+  for (const [extra, why] of [
+    [{ algs: ['HS256'] }, /algs\[0\] must be one of .*HS\* and none are refused/],
+    [{ algs: ['none'] }, /algs\[0\] must be one of/],
+    [{ subjects: [{ sub: 'u', name: 'tester' }] }, /subjects\[0\]\.name must not be tester or human/],
+    [{ subjects: [{ sub: 'u', name: 'Human' }] }, /subjects\[0\]\.name must not be tester or human/],
+  ]) await assert.rejects(start(a, extra), why);
+  const refusedAtDiscovery = /console\.sso provider \w+ refused at discovery/;
+  // The mosaic-preview shape: HS256 only.
+  const hs = op.issuer('hs', { discovery: { id_token_signing_alg_values_supported: ['HS256'] } });
+  await assert.rejects(start(hs, { algs: ['RS256'] }), refusedAtDiscovery);
+  const empty = op.issuer('empty');
+  empty.jwksOverride = { keys: [] };
+  await assert.rejects(start(empty), refusedAtDiscovery);
+  const plain = op.issuer('plain', { discovery: { code_challenge_methods_supported: ['plain'] } });
+  await assert.rejects(start(plain), refusedAtDiscovery);
+  const moved = op.issuer('moved');
+  moved.discovery = { issuer: `${op.base}/elsewhere/` };
+  await assert.rejects(start(moved), refusedAtDiscovery);
+  const small = op.issuer('small', { keys: [rsaKey('small', 1024)] });
+  await assert.rejects(start(small), refusedAtDiscovery);
+  // The control: the same OP and provider start.
+  const sso = await start(a);
+  assert.deepEqual(sso.health(), { a: 'ready' });
+  sso.close();
+  await assert.rejects(startServer({ port: 0, sso, preview: { host: HOST, header: 'remote-user', user: 'jason' } }), /--sso cannot be combined/);
+});
+
+test('11: slot files: a symlink, mode 0644, mode 0640 and a file under the repository are refused, and no message holds the value', t => {
+  const root = mkdtempSync(join(tmpdir(), 'webui-sso-slot-'));
+  t.after(() => rmSync(root, { recursive: true, force: true }));
+  const dir = join(root, 'config'), slots = join(dir, 'secrets', 'mosaic-stack');
+  mkdirSync(slots, { recursive: true });
+  const provider = slot => ({ id: 'a', clientSecret: { slot } });
+  const value = 'slot-value-do-not-print';
+  const opts = { repo: join(root, 'repo'), copies: join(root, 'copies') };
+  writeFileSync(join(slots, 'good'), `${value}\n`, { mode: 0o600 });
+  assert.equal(readSlot(dir, provider('good'), opts), value);
+  writeFileSync(join(root, 'target'), value, { mode: 0o600 });
+  symlinkSync(join(root, 'target'), join(slots, 'link'));
+  for (const [slot, mode] of [['wide', 0o644], ['group', 0o640]]) { writeFileSync(join(slots, slot), value); chmodSync(join(slots, slot), mode); }
+  writeFileSync(join(slots, 'two'), `${value}\nmore\n`, { mode: 0o600 });
+  writeFileSync(join(slots, 'empty'), '\n', { mode: 0o600 });
+  const cases = [
+    ['missing', /slot is missing$/, opts],
+    ['link', /must not be a symbolic link$/, opts],
+    ['wide', /must have no group or other permission bits$/, opts],
+    ['group', /must have no group or other permission bits$/, opts],
+    ['two', /must hold one non-empty line$/, opts],
+    ['empty', /must hold one non-empty line$/, opts],
+    // The config dir itself under the repository, and under a --checkout.
+    ['good', /must not be inside the repository or a stack copy$/, { ...opts, repo: root }],
+    ['good', /must not be inside the repository or a stack copy$/, { ...opts, checkout: dir }],
+    ['good', /must not be inside the repository or a stack copy$/, { ...opts, copies: dir }],
+  ];
+  for (const [slot, why, o] of cases) {
+    let err = null;
+    try { readSlot(dir, provider(slot), o); } catch (e) { err = e; }
+    assert.ok(err, `${slot} was read`);
+    assert.match(err.message, /^console\.sso provider a client secret slot /);
+    assert.match(err.message, why, slot);
+    assert.equal(err.message.includes(value), false);
+    assert.equal(err.message.includes(root), false);
+  }
+});
+
+test('11: the CLI refuses --sso with the old flags and without console.sso, and starts with a good one', async t => {
+  const root = mkdtempSync(join(tmpdir(), 'wsso-'));
+  t.after(() => rmSync(root, { recursive: true, force: true }));
+  const env = { ...process.env, MOSAIC_CONFIG: join(root, 'cfg', 'config.json'), XDG_DATA_HOME: join(root, 'xdg') };
+  for (const flags of [['--auth-header', 'remote-user'], ['--public-host', HOST], ['--allow-user', 'jason'], ['--proof-header', 'x-proof']]) {
+    const r = spawnSync(process.execPath, [CLI, 'serve', '--port', '0', '--sso', ...flags], { encoding: 'utf8', timeout: 10000, env });
+    assert.equal(r.status, 2, flags.join(' '));
+    assert.match(r.stderr, /^refused: --sso cannot be combined with --public-host, --auth-header, --allow-user or --proof-\*$/m);
+  }
+  const missing = spawnSync(process.execPath, [CLI, 'serve', '--port', '0', '--sso'], { encoding: 'utf8', timeout: 10000, env });
+  assert.equal(missing.status, 2);
+  assert.match(missing.stderr, /^refused: --sso needs the system config \(/);
+  const op = await fakeOidc();
+  t.after(() => op.close());
+  const a = op.issuer('a');
+  PRODUCED.add(a.clientSecret);
+  mkdirSync(join(root, 'cfg', 'secrets', 'mosaic-stack'), { recursive: true });
+  writeFileSync(join(root, 'ca.pem'), op.cert);
+  const base = { configVersion: 1, environment: 'development', dataRoot: join(root, 'data'), execution: { backend: 'docker', provider: 'zai', model: 'm' } };
+  writeFileSync(env.MOSAIC_CONFIG, JSON.stringify(base));
+  const noKey = spawnSync(process.execPath, [CLI, 'serve', '--port', '0', '--sso'], { encoding: 'utf8', timeout: 10000, env });
+  assert.equal(noKey.status, 2);
+  assert.match(noKey.stderr, /^refused: --sso needs console\.sso in the system config$/m);
+  writeFileSync(env.MOSAIC_CONFIG, JSON.stringify({ ...base, console: { sso: { publicOrigin: ORIGIN, providers: [providerFor(a)] } } }));
+  writeFileSync(join(root, 'cfg', 'secrets', 'mosaic-stack', 'a'), `${a.clientSecret}\n`, { mode: 0o644 });
+  const wide = spawnSync(process.execPath, [CLI, 'serve', '--port', '0', '--sso'], { encoding: 'utf8', timeout: 10000, env });
+  assert.equal(wide.status, 2);
+  assert.match(wide.stderr, /^refused: console\.sso provider a client secret slot must have no group or other permission bits$/m);
+  chmodSync(join(root, 'cfg', 'secrets', 'mosaic-stack', 'a'), 0o600);
+  // The child trusts the fake OP's certificate through NODE_EXTRA_CA_CERTS; the code under test has no flag for it.
+  const child = spawn(process.execPath, [CLI, 'serve', '--port', '0', '--sso'], { env: { ...env, NODE_EXTRA_CA_CERTS: join(root, 'ca.pem') } });
+  t.after(() => child.kill('SIGKILL'));
+  let out = '', err = '';
+  child.stderr.on('data', c => (err += c));
+  await new Promise((resolve, reject) => {
+    const timer = setTimeout(() => reject(new Error(`no start line: ${out} ${err}`)), 15000);
+    child.stdout.on('data', c => { out += c; if (out.includes('Ctrl-C')) { clearTimeout(timer); resolve(); } });
+    child.on('exit', () => { clearTimeout(timer); reject(new Error(`exited: ${err}`)); });
+  });
+  assert.match(out, new RegExp(`^Sign-in: ${ORIGIN}/ \\(--sso\\), read-only$`, 'm'));
+  assert.match(out, new RegExp(`^Sign-in provider: a issuer ${a.issuer.replace(/[.]/g, '\\.')} subjects 1 \\(ready\\)$`, 'm'));
+  assert.equal(out.includes(a.clientSecret) || err.includes(a.clientSecret), false);
+  assert.equal(out.includes(a.clientId), false);
+  const port = Number(out.match(/^Mosaic Console: http:\/\/127\.0\.0\.1:(\d+)\//m)[1]);
+  const health = await call(port, { path: '/healthz', host: `127.0.0.1:${port}` });
+  assert.deepEqual(health.body, { ok: true, sso: { a: 'ready' } });
+  child.kill('SIGTERM');
+});
+
+test('12: under --sso the tester listener refuses each kind of sign-in, has no /auth, and startServer refuses tester with sso', async t => {
+  const env = await setup(t);
+  const tester = await startServer({ port: 0, board: 'http://127.0.0.1:9', bus: env.bus, tester: true, testerNoSignIn: true, log: () => {} });
+  t.after(() => close(tester));
+  const port = tester.address().port, host = `127.0.0.1:${port}`;
+  const { session, g, begun } = await signIn(env);
+  assert.ok(session);
+  const plain = await call(port, { path: '/api/config', host });
+  assert.equal(plain.status, 200, 'control: a request with no sign-in is served');
+  for (const headers of [
+    { cookie: session },
+    { cookie: `theme=dark; ${begun.cookie}` },
+    { cookie: `${SESSION_COOKIE.toLowerCase()}=x` },
+    { authorization: `Bearer ${g.idToken}` },
+    { 'x-authentik-jwt': g.idToken },
+    { 'X-Authentik-Username': 'jason.woltje' },
+  ]) {
+    const r = await call(port, { path: '/api/config', host, headers });
+    assert.equal(r.status, 403, JSON.stringify(Object.keys(headers)));
+    assert.deepEqual(r.body, { error: 'tester listener takes no sign-in' });
+  }
+  assert.equal((await call(port, { path: '/auth/login', host })).status, 404);
+  await assert.rejects(startServer({ port: 0, tester: true, sso: env.sso }), /tester listener cannot use sso/);
+});
+
+test('13: idle and absolute expiry, logout then reuse, a cross-origin logout, and background reads that don\'t keep a session', async t => {
+  const env = await setup(t);
+  const read = cookie => call(env.port, { path: '/api/bus/inbox', headers: { cookie } });
+  const record = () => [...env.sso.sessions.values()].at(-1);
+  // Background reads don't move `seen`; a page load does.
+  let { session } = await signIn(env);
+  const old = Date.now() - 59 * 60 * 1000;
+  record().seen = old;
+  assert.equal((await read(session)).status, 200);
+  assert.equal(record().seen, old, 'a background read refreshed the session');
+  assert.equal((await call(env.port, { path: '/', headers: { cookie: session } })).status, 200);
+  assert.ok(record().seen > old, 'a page load did not refresh the session');
+  // Idle: 59 minutes of background reads, then one more past the hour.
+  record().seen = Date.now() - 61 * 60 * 1000;
+  assert.equal((await read(session)).status, 401);
+  // Absolute.
+  ({ session } = await signIn(env));
+  record().created = Date.now() - 8 * 3600 * 1000;
+  assert.equal((await call(env.port, { path: '/', headers: { cookie: session } })).headers.location, '/auth/login?return=%2F');
+  // Logout needs same-origin; refused, the session stays.
+  ({ session } = await signIn(env));
+  const cross = await call(env.port, { method: 'POST', path: '/auth/logout', headers: { cookie: session, origin: ORIGIN, 'sec-fetch-site': 'cross-site' } });
+  assert.equal(cross.status, 403);
+  assert.equal((await read(session)).status, 200);
+  const noOrigin = await call(env.port, { method: 'POST', path: '/auth/logout', headers: { cookie: session, 'sec-fetch-site': 'same-origin' } });
+  assert.equal(noOrigin.status, 403);
+  assert.equal((await read(session)).status, 200);
+  const out = await call(env.port, { method: 'POST', path: '/auth/logout', headers: { cookie: session, origin: ORIGIN, 'sec-fetch-site': 'same-origin' } });
+  assert.equal(out.status, 303);
+  const end = new URL(out.headers.location);
+  assert.equal(`${end.origin}${end.pathname}`, `${env.iss[0].issuer}end-session`);
+  assert.equal(end.searchParams.get('post_logout_redirect_uri'), `${ORIGIN}/auth/signed-out`);
+  assert.equal(end.searchParams.get('client_id'), env.iss[0].clientId);
+  assert.ok(end.searchParams.get('id_token_hint'));
+  assert.deepEqual(setCookies(out), [`${SESSION_COOKIE}=; Path=/; Secure; HttpOnly; SameSite=Lax; Max-Age=0`]);
+  assert.equal((await read(session)).status, 401);
+  assert.equal((await call(env.port, { method: 'GET', path: '/auth/logout', headers: { cookie: session } })).status, 405);
+});
+
+test('13: the CSP lets the Sign out form reach the provider\'s end-session origin, and only under --sso', async t => {
+  const env = await setup(t);
+  const r = await call(env.port, { path: '/healthz', host: `127.0.0.1:${env.port}` });
+  assert.match(r.headers['content-security-policy'], new RegExp(`; form-action 'self' ${env.op.base.replace(/[.]/g, '\\.')}$`));
+  const plain = await startServer({ port: 0, board: 'http://127.0.0.1:9' });
+  t.after(() => close(plain));
+  const p = await call(plain.address().port, { path: '/healthz', host: `127.0.0.1:${plain.address().port}` });
+  assert.match(p.headers['content-security-policy'], /; form-action 'self'$/);
+});
+
+test('14: open redirects land on /, and a path on the Console lands there', async t => {
+  const env = await setup(t);
+  for (const [query, where] of [
+    ['return=%2F%2Fevil.example', `${ORIGIN}/`],
+    ['return=https%3A%2F%2Fevil.example', `${ORIGIN}/`],
+    ['return=%2F%5Cevil.example', `${ORIGIN}/`],
+    ['return=/%09/evil.example', `${ORIGIN}/`],
+    // Dot segments that leave a pathname of //evil.example stay on the Console (webby-0019 B1).
+    ['return=%2F.%2F%2Fevil.example', `${ORIGIN}//evil.example`],
+    ['return=%2Fx%2F..%2F%2Fevil.example', `${ORIGIN}//evil.example`],
+    [`return=${encodeURIComponent(`${ORIGIN}//evil.example`)}`, `${ORIGIN}//evil.example`],
+    ['return=%2Fboard%2F.%2Fx', `${ORIGIN}/board/x`],
+    ['return=%2Fboard%3Fx%3D1', `${ORIGIN}/board?x=1`],
+    ['', `${ORIGIN}/`],
+  ]) {
+    const begun = await begin(env, { query });
+    const r = await callback(env, begun, { code: grant(env, begun, env.iss[0]).code });
+    assert.equal(r.status, 303);
+    assert.equal(r.headers.location, where, query);
+    assert.equal(new URL(r.headers.location).origin, ORIGIN, query);
+    PRODUCED.add(sessionOf(r).split('=')[1]);
+  }
+});
+
+test('15: a callback for A carrying B\'s code and iss, and a provider= query, is refused', async t => {
+  const env = await setup(t, { issuers: [{ name: 'a' }, { name: 'b' }] });
+  const [, b] = env.iss;
+  for (const extra of [{ iss: b.issuer, provider: 'b' }, { provider: 'b' }]) {
+    const begun = await begin(env, { provider: 'a' });
+    // B's code against A's PKCE challenge and nonce, for B's own subject: only the record rule
+    // (this callback belongs to A) stands in the way.
+    const g = grant(env, begun, b, { sub: 'user-b' });
+    const r = await callback(env, begun, { code: g.code, extra });
+    refused(env, r);
+  }
+  assert.equal(b.tokenRequests.length, 0, 'B\'s token endpoint was called');
+});
+
+test('16: a provider with RS256 and ES256 takes either, and refuses PS256 with a usable PS256 key in the JWKS', async t => {
+  const rsa = rsaKey(), ec = ecKey(), ps = psKey();
+  const env = await setup(t, { issuers: [{ name: 'a', keys: [rsa, ec, ps] }], provider: { a: { algs: ['RS256', 'ES256'] } } });
+  assert.ok((await signIn(env, { opts: { key: rsa } })).session);
+  assert.ok((await signIn(env, { opts: { key: ec } })).session);
+  refused(env, (await signIn(env, { opts: { key: ps } })).r, 'id-token-invalid');
+});
+
+test('17: 33 started logins leave 32 records, and the first one\'s callback finds none', async t => {
+  const env = await setup(t);
+  const first = await begin(env);
+  for (let i = 0; i < 32; i++) await begin(env);
+  assert.equal(env.sso.logins.size, 32);
+  refused(env, await callback(env, first, { code: grant(env, first, env.iss[0]).code }), 'login-record-missing');
+});
+
+test('18: after a key rotation a sign-in works through one refetch, and the removed kid is refused', async t => {
+  const env = await setup(t);
+  const [iss] = env.iss;
+  t.mock.timers.enable({ apis: ['Date'], now: Date.now() });
+  const old = iss.keys[0];
+  assert.ok((await signIn(env)).session);
+  const fetches = iss.jwksFetches;
+  env.op.rotate(iss);
+  t.mock.timers.tick(61000);
+  assert.ok((await signIn(env)).session);
+  assert.equal(iss.jwksFetches, fetches + 1);
+  refused(env, (await signIn(env, { opts: { key: old } })).r, 'signature-invalid');
+});
+
+test('20 and 21: the store holds no raw session id, and the cookie strings are exact', async t => {
+  const env = await setup(t);
+  const begun = await begin(env);
+  assert.match(setCookies(begun.r)[0], new RegExp(`^${LOGIN_COOKIE}=[A-Za-z0-9_-]{43}; Path=/; Secure; HttpOnly; SameSite=Lax; Max-Age=600$`));
+  for (const key of env.sso.logins.keys()) assert.match(key, /^[0-9a-f]{64}$/);
+  const r = await callback(env, begun, { code: grant(env, begun, env.iss[0]).code });
+  const set = setCookies(r);
+  assert.equal(set.length, 2);
+  assert.equal(set[0], `${LOGIN_COOKIE}=; Path=/; Secure; HttpOnly; SameSite=Lax; Max-Age=0`);
+  assert.match(set[1], new RegExp(`^${SESSION_COOKIE}=[A-Za-z0-9_-]{43}; Path=/; Secure; HttpOnly; SameSite=Lax$`));
+  const id = set[1].split(';')[0].split('=')[1];
+  PRODUCED.add(id);
+  for (const [key, value] of env.sso.sessions) {
+    assert.match(key, /^[0-9a-f]{64}$/);
+    assert.notEqual(key, id);
+    assert.equal(JSON.stringify(value).includes(id), false);
+  }
+});
+
+test('22: a loopback Host is 403 on a page, a read and a write; /healthz on loopback is 200; a redirect_uri never comes from the Host', async t => {
+  const env = await setup(t);
+  const { session } = await signIn(env);
+  const loop = `127.0.0.1:${env.port}`;
+  for (const [method, path, body] of [['GET', '/', undefined], ['GET', '/api/board', undefined], ['GET', '/api/bus/inbox', undefined], ['POST', '/api/bus/message', MSG]]) {
+    // A loopback Host on this listener's port; any other Host is already the older non-local refusal.
+    for (const host of [loop, `localhost:${env.port}`]) {
+      const r = await call(env.port, { method, path, host, body, headers: { cookie: session, 'content-type': 'application/json' } });
+      assert.equal(r.status, 403, `${method} ${path} ${host}`);
+      assert.deepEqual(r.body, { error: 'public Host required' });
+    }
+  }
+  const health = await call(env.port, { path: '/healthz', host: loop });
+  assert.equal(health.status, 200);
+  assert.deepEqual(health.body, { ok: true, sso: { a: 'ready' } });
+  assert.equal(env.sends.length, 0);
+  const begun = await begin(env, { host: HOST.toUpperCase() });
+  assert.equal(begun.params.get('redirect_uri'), `${ORIGIN}/auth/callback`);
+});
+
+test('23: a provider down at start leaves the Console up and 503, and the retry makes sign-in work', async t => {
+  let env = await setup(t, { retryFirst: 50, before: (op, [a]) => { a.mode = 'down'; } });
+  assert.equal((await call(env.port, { path: '/auth/login' })).status, 503);
+  assert.deepEqual((await call(env.port, { path: '/healthz', host: `127.0.0.1:${env.port}` })).body.sso, { a: 'unreachable' });
+  assert.match(env.lines.at(-1), / sso refused code=discovery-failed provider=a$/);
+  env.iss[0].mode = 'ok';
+  for (let i = 0; i < 100 && env.sso.health().a !== 'ready'; i++) await new Promise(r => setTimeout(r, 20));
+  assert.deepEqual(env.sso.health(), { a: 'ready' });
+  assert.ok((await signIn(env)).session);
+  // A 200 HTML page at the discovery URL is unreachable too, and the Console starts.
+  env = await setup(t, { before: (op, [a]) => { a.mode = 'html'; } });
+  assert.deepEqual(env.sso.health(), { a: 'unreachable' });
+  // HS-only discovery at start refuses the start.
+  await assert.rejects(setup(t, { before: (op, [a]) => { a.discovery = { id_token_signing_alg_values_supported: ['HS256'] }; } }), /refused at discovery/);
+});
+
+test('19: no captured log line holds a token, code, state, nonce, verifier, client secret or session id', () => {
+  assert.ok(ALL_LINES.length > 20, `only ${ALL_LINES.length} lines`);
+  assert.ok(PRODUCED.size > 50, `only ${PRODUCED.size} values`);
+  for (const line of ALL_LINES) {
+    for (const value of PRODUCED) if (value) assert.equal(line.includes(value), false, `a log line holds a produced value: ${line.slice(0, 80)}`);
+    assert.match(line, /^\S+ (sso refused code=[a-z-]+ provider=[a-z0-9-]+( iss="[^"]*" sub="[^"]*")?|send user="[^"]+" to="[^"]*" (id=msg-0001|error=[a-z -]+))$/, line);
+  }
+});
@@ -26,6 +26,7 @@ import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
 import process from "node:process";
+import { pathToFileURL } from "node:url";

 const SUPPORTED_CONFIG_VERSION = 1;
 const SUPPORTED_ENVIRONMENTS = new Set(["development", "production"]);
@@ -106,13 +107,30 @@ function isAncestorOf(ancestor, candidate) {
  return rel !== "" && !rel.startsWith("..") && !path.isAbsolute(rel);
 }

-function validate(document, file) {
+// Q175 phase 1 (#1690): the optional `console` key, checked for shape only by the Console's own
+// checker. It is imported only when the key is there, so a config without it never needs the
+// Console's code, and a copy of this file alone still reads one.
+async function validateConsole(value) {
+  let checkConsole;
+  try {
+    ({ checkConsole } = await import(pathToFileURL(path.join(import.meta.dirname, "..", "packages", "webui", "src", "sso-config.mjs")).href));
+  } catch {
+    fail(2, 'the "console" key needs packages/webui/src/sso-config.mjs beside this loader');
+  }
+  try {
+    return checkConsole(value);
+  } catch (error) {
+    fail(2, error.message);
+  }
+}
+
+async function validate(document, file) {
  if (!isPlainObject(document)) {
    fail(2, "configuration must be a JSON object");
  }
  rejectUnknownKeys(
    document,
-    ["configVersion", "environment", "dataRoot", "execution"],
+    ["configVersion", "environment", "dataRoot", "execution", "console"],
    "configuration",
  );

@@ -146,6 +164,10 @@ function validate(document, file) {
    fail(2, `unsupported execution.adapter: ${JSON.stringify(adapter)} (supported: ${[...SUPPORTED_ADAPTERS].join(", ")})`);
  }

+  // Last, so the older checks keep their order. The key is in the output only when the file has
+  // it, so a config without it prints what it always printed.
+  const consoleKey = Object.hasOwn(document, "console") ? await validateConsole(document.console) : undefined;
+
  return {
    configVersion: document.configVersion,
    environment: document.environment,
@@ -156,10 +178,11 @@ function validate(document, file) {
      model: document.execution.model,
      adapter,
    },
+    ...(consoleKey === undefined ? {} : { console: consoleKey }),
  };
 }

-function load(file) {
+async function load(file) {
  const raw = readRaw(file);
  if (raw === null) {
    fail(3, `configuration not found: ${file} (run scripts/bootstrap.sh to create it)`);
@@ -170,7 +193,7 @@ function load(file) {
  } catch (error) {
    fail(2, `configuration is not valid JSON (${file}): ${error.message}`);
  }
-  return validate(document, file);
+  return await validate(document, file);
 }

 function shellQuote(value) {
@@ -194,7 +217,7 @@ const file = configPath();
 switch (operation) {
  case "bootstrap": {
    if (fs.existsSync(file)) {
-      load(file); // validate only; never rewrite
+      await load(file); // validate only; never rewrite
      process.stderr.write(`mosaic-config: configuration already present, validated without changes: ${file}\n`);
      process.exit(0);
    }
@@ -206,26 +229,26 @@ switch (operation) {
      fs.writeFileSync(fd, `${JSON.stringify(DEFAULT_CONFIG, null, 2)}\n`);
    } catch (error) {
      if (error.code === "EEXIST") {
-        load(file);
+        await load(file);
        process.exit(0);
      }
      fail(1, `unable to create configuration: ${error.message}`);
    } finally {
      if (fd !== undefined) fs.closeSync(fd);
    }
-    load(file);
+    await load(file);
    process.stderr.write(`mosaic-config: created default configuration: ${file}\n`);
    process.exit(0);
  }

  case "validate": {
-    const resolved = load(file);
+    const resolved = await load(file);
    process.stdout.write(`${JSON.stringify(resolved, null, 2)}\n`);
    process.exit(0);
  }

  case "env": {
-    const resolved = load(file);
+    const resolved = await load(file);
    process.stdout.write(
      [
        `MOSAIC_DATA_ROOT=${shellQuote(resolved.dataRoot)}`,
@@ -151,6 +151,52 @@ else
    FAIL=$((FAIL+1)); echo "${C_FAIL}FAIL${C_RESET} env exports resolve correctly"
 fi

+# --- Q175 phase 1 (#1690), design test 25: the optional console key ---
+# Shape only. The slot path is a FIFO, so a loader that opened the slot would block and the
+# timeout would fail the case; no case reads a slot file.
+mkdir -p "$SANDBOX/secrets/mosaic-stack"
+mkfifo "$SANDBOX/secrets/mosaic-stack/console-sso-test"
+sso_body() {
+    printf '{"configVersion":1,"environment":"development","dataRoot":"%s","execution":{"backend":"docker","provider":"zai","model":"m"},"console":%s}' "$DATA_ROOT" "$1"
+}
+# provider [ALGS] [CLIENT_SECRET]: one provider entry; an empty argument takes the valid value.
+provider() {
+    local algs='["RS256"]' secret='{"slot":"console-sso-test"}'
+    [ -n "${1:-}" ] && algs="$1"
+    [ -n "${2:-}" ] && secret="$2"
+    printf '{"id":"fake","issuer":"https://op.test/app/","clientId":"client-1","clientSecret":%s,"algs":%s,"subjects":[{"sub":"user-1","name":"jason.woltje"}]}' "$secret" "$algs"
+}
+cfg sso-valid.json "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider)"']}}')"
+OUT="$(MOSAIC_CONFIG="$SANDBOX/sso-valid.json" timeout 20 $CONFIG_OP validate 2>&1)"
+[ $? -eq 0 ] && printf '%s' "$OUT" | grep -q '"publicOrigin": "https://console.test"'
+check "valid console.sso loads and is in the output" $?
+
+# expect_refusal NAME PATH-IN-MESSAGE BODY: exit 2, and the message names the bad key path.
+expect_refusal() {
+    cfg sso-bad.json "$2"
+    local err rc
+    err="$(MOSAIC_CONFIG="$SANDBOX/sso-bad.json" timeout 20 $CONFIG_OP validate 2>&1 >/dev/null)"
+    rc=$?
+    [ "$rc" -eq 2 ] && printf '%s' "$err" | grep -qF -- "$3"
+    check "$1 (exit $rc)" $?
+}
+expect_refusal "console.sso HS256 alg exits 2 naming the path" \
+    "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider '["HS256"]')"']}}')" 'console.sso.providers[0].algs[0] must be one of'
+expect_refusal "console.sso alg none exits 2 naming the path" \
+    "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider '["RS256","none"]')"']}}')" 'console.sso.providers[0].algs[1] must be one of'
+expect_refusal "console.sso missing slot field exits 2 naming the path" \
+    "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider '' '{}')"']}}')" 'console.sso.providers[0].clientSecret.slot is required'
+expect_refusal "console.sso slot name outside the pattern exits 2 naming the path" \
+    "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider '' '{"slot":"../x"}')"']}}')" 'console.sso.providers[0].clientSecret.slot must match'
+expect_refusal "unknown key under console exits 2 naming the path" \
+    "$(sso_body '{"sso":{"publicOrigin":"https://console.test","providers":['"$(provider)"']},"extra":1}')" 'console.extra is not a supported key'
+
+# Without the key: the output is exactly what the loader printed before phase 1 (sage-1340, F2).
+cfg no-console.json '{"configVersion":1,"environment":"development","dataRoot":"'$DATA_ROOT'","execution":{"backend":"docker","provider":"zai","model":"m"}}'
+EXPECTED="$(printf '{\n  "configVersion": 1,\n  "environment": "development",\n  "dataRoot": "%s",\n  "execution": {\n    "backend": "docker",\n    "provider": "zai",\n    "model": "m",\n    "adapter": "pi"\n  }\n}' "$DATA_ROOT")"
+[ "$(MOSAIC_CONFIG="$SANDBOX/no-console.json" timeout 20 $CONFIG_OP validate)" = "$EXPECTED" ]
+check "config without console loads with unchanged output" $?
+
 # --- validation must not modify the file ---
 SUM_INVALID_BEFORE=$(sha256sum "$SANDBOX/invalid.json" | cut -d' ' -f1)
 MOSAIC_CONFIG="$SANDBOX/invalid.json" $CONFIG_OP validate >/dev/null 2>&1
@@ -49,6 +49,9 @@
 # character set and refused otherwise. --proof-header NAME --proof-file PATH
 # go together under preview; only the path is carried here, never the secret.
 # render checks ownership, mode and location without opening the proof file.
+# --sso (Q175 phase 1, #1690): the Console signs people in itself from
+# console.sso in config.json. It refuses the preview set and the proof pair,
+# and --send takes it in place of the preview set. Nothing secret is carried.
 #
 # There is no start, stop, enable or restart verb. The Console reads the
 # main listener's bus through the human transport; the optional loopback
@@ -68,7 +71,7 @@ REPO="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 TEMPLATE="$REPO/packages/webui/systemd/mosaic-webui.service.in"
 UNIT_NAME="mosaic-webui.service"
 USAGE="usage: scripts/webui-service.sh copy COMMIT [--copies DIR] [--allow-worktree] | render [--copy ID [--copies DIR]] [FLAGS] | install --copy ID [--copies DIR] [--dir DIR] [--no-reload] [--allow-worktree] [FLAGS] | uninstall [--dir DIR] [--no-reload] | status [--dir DIR]
-  FLAGS: [--port N] [--business ID] [--board URL] [--public-host NAME --auth-header HEADER --allow-user ID [--send]] [--tester-port N] [--proof-header NAME --proof-file PATH]
+  FLAGS: [--port N] [--business ID] [--board URL] [--sso [--send] | --public-host NAME --auth-header HEADER --allow-user ID [--send]] [--tester-port N] [--proof-header NAME --proof-file PATH]
  --tester-port: 1024..65535, different from --port and never 7332; loopback tester listener.
  --allow-worktree is for the tests only: copy and install otherwise refuse outside the canonical checkout."

@@ -91,6 +94,7 @@ PUBLIC_HOST=""
 AUTH_HEADER=""
 ALLOW_USER=""
 SEND=0
+SSO=0
 PROOF_HEADER=""
 PROOF_FILE=""
 PROOF_SET=0
@@ -114,6 +118,7 @@ parse_flags() {
            --proof-header) [ $# -ge 2 ] || usage; PROOF_HEADER="$2"; PROOF_SET=1; SERVE_SET=1; shift 2 ;;
            --proof-file) [ $# -ge 2 ] || usage; PROOF_FILE="$2"; PROOF_SET=1; SERVE_SET=1; shift 2 ;;
            --send) SEND=1; SERVE_SET=1; shift ;;
+            --sso) SSO=1; SERVE_SET=1; shift ;;
            *) usage ;;
        esac
    done
@@ -166,9 +171,13 @@ serve_flags() {
    [ -z "$PUBLIC_HOST" ] || preview=$((preview + 1))
    [ -z "$AUTH_HEADER" ] || preview=$((preview + 1))
    [ -z "$ALLOW_USER" ] || preview=$((preview + 1))
-    # serve refuses --send without the preview set; refuse it here first,
-    # so no unit is written that would only exit 2 at start.
-    [ "$SEND" = 0 ] || [ "$preview" -eq 3 ] || die "--send needs the preview mode (--public-host, --auth-header and --allow-user)"
+    # serve refuses --sso with the preview set or the proof pair, and --send
+    # without --sso or the preview set; refuse them here first, so no unit is
+    # written that would only exit 2 at start.
+    if [ "$SSO" = 1 ] && { [ "$preview" -ne 0 ] || [ "$PROOF_SET" = 1 ]; }; then
+        die "--sso cannot be combined with --public-host, --auth-header, --allow-user or --proof-*"
+    fi
+    [ "$SEND" = 0 ] || [ "$preview" -eq 3 ] || [ "$SSO" = 1 ] || die "--send needs the preview mode (--public-host, --auth-header and --allow-user) or --sso"
    if [ "$preview" -ne 0 ]; then
        [ "$preview" -eq 3 ] || die "--public-host, --auth-header and --allow-user go together: all three or none"
        case "$PUBLIC_HOST" in [A-Za-z0-9]*) ;; *) die "public host must be a hostname, no port or scheme: $PUBLIC_HOST" ;; esac
@@ -201,6 +210,7 @@ serve_flags() {
        { [ "$proof_mode" = 600 ] || [ "$proof_mode" = 400 ]; } && [ "$proof_uid" = "$(id -u)" ] || die "invalid proxy proof file metadata"
        flags="$flags --proof-header $PROOF_HEADER --proof-file $PROOF_FILE"
    fi
+    [ "$SSO" = 0 ] || flags="$flags --sso"
    [ "$SEND" = 0 ] || flags="$flags --send"
    [ "$TESTER_SET" = 0 ] || flags="$flags --tester-port $TESTER_PORT"
    echo "$flags"
@@ -385,14 +395,17 @@ status_unit() {
    else
        echo "copy: none; the unit runs from $wd"
    fi
-    # render puts --send after the allowed user and optional proof pair,
-    # before the tester port. The allowed user
+    # render puts --send after the allowed user and optional proof pair, or
+    # after --sso, before the tester port. The allowed user
    # starts with a letter or digit (N5), so it is never the value --send.
-    if grep -Eq '^ExecStart=.* --allow-user [^ ][^ ]*( --proof-header [^ ]+ --proof-file /[^ ]+)? --send( --tester-port [0-9]+)?$' "$target"; then
+    if grep -Eq '^ExecStart=.*( --allow-user [^ ][^ ]*( --proof-header [^ ]+ --proof-file /[^ ]+)?| --sso) --send( --tester-port [0-9]+)?$' "$target"; then
        echo "send: on (--send; human messages to roles)"
    else
        echo "send: off (read-only)"
    fi
+    if grep -Eq '^ExecStart=.* --sso( --send)?( --tester-port [0-9]+)?$' "$target"; then
+        echo "sign-in: the Console's own (--sso)"
+    fi
    local tester_port
    tester_port="$(sed -n 's/^ExecStart=.* --tester-port \([0-9][0-9]*\)$/\1/p' "$target")"
    if [ -n "$tester_port" ]; then