diff --git a/PROJECT_STATE.md b/PROJECT_STATE.md
index 919e7c74..e369408e 100644
--- a/PROJECT_STATE.md
+++ b/PROJECT_STATE.md
@@ -61,6 +61,10 @@
   `rest_api` acceptance, the 48-hour/two-ETL observation, and revocation of `legacy-shared` are
   mandatory before `SURVEY_GO_PROJECT_B`. Current authorization covers read-only survey and
   preparation only; old-stack stop and new-stack start remain forbidden.
+- **Runtime-projection preparation (2026-08-22):** the source contract and hermetic gates prepare
+  root-only canonical authentication plus a separate `10001:10001` read-only core projection.
+  This is implementation preparation and test evidence only. Project A has not been started;
+  applying its descriptor or any server runtime root still needs explicit authorization.
 
 ### Authentication final-review fix round 2 — remediation PASS, release gates remain (2026-08-18)
 
diff --git a/docs/install/authentication-local.md b/docs/install/authentication-local.md
index 8e95f1df..c59c6290 100644
--- a/docs/install/authentication-local.md
+++ b/docs/install/authentication-local.md
@@ -68,3 +68,14 @@ values into tickets, logs, or evidence.
 
 Check readiness with `tht auth check`; add `--json` for the machine contract. Use
 `tht doctor --json` for the aggregate installation report.
+
+## Projected server installations
+
+This section applies only when a Linux `profile: server` descriptor declares a runtime projection.
+The canonical authentication root stays root-owned and is the only authority. The container reads
+only the separate read-only runtime projection selected by `CURRENT`; it never falls back to the
+canonical files or to a previous generation. Run projected mutations and repairs through the
+root-operated `tht` commands documented in the [server guide](server.md), and never edit runtime
+files directly.
+
+Mac, Windows, and local direct-file authentication remain unchanged when the projection is absent.
diff --git a/docs/install/examples/thothii-installation.server.yaml b/docs/install/examples/thothii-installation.server.yaml
index ab3e2912..3072b67c 100644
--- a/docs/install/examples/thothii-installation.server.yaml
+++ b/docs/install/examples/thothii-installation.server.yaml
@@ -8,7 +8,13 @@ workspaceRepository:
   branch: main
   access: ssh
 authentication:
-  configDirectory: "/absolute/path/to/thothii-auth"
+  # Root-operated source of truth; it is never mounted into core.
+  configDirectory: "/srv/example/thothii/auth-canonical"
+  runtimeProjection:
+    # The only authentication bind exposed to core by the automatic override.
+    directory: "/srv/example/thothii/auth-runtime"
+    uid: 10001
+    gid: 10001
 overrides:
   - "/absolute/path/to/ThothII/deploy/compose.session-server.yaml.example"
   - "/absolute/path/to/ThothII/deploy/compose.git-ssh.yaml"
diff --git a/docs/install/server.md b/docs/install/server.md
index fce84281..ca1e67ad 100644
--- a/docs/install/server.md
+++ b/docs/install/server.md
@@ -88,6 +88,73 @@ Expected: the parent is `operator_uid:10001 750`; source/operator are
 `10001:10001 750`; backups are `0:0 700`. Re-run the empty `getent` checks after creation. Do not
 make `/srv/thothii` a shared application directory.
 
+## Projected server authentication: canonical root and runtime projection
+
+For a server descriptor that declares `authentication.runtimeProjection`, authentication has two
+different roots. The **canonical authentication root** (`authentication.configDirectory`) is the
+root-operated source of truth. It and its regular files are `root:root 0700/0600`. The **runtime
+projection** is a separate Linux-only tree for the container reader: its root, `generations`, and
+generation directories are `10001:10001 0700`; `CURRENT`, `manifest.json`, `auth.yaml`, and (for
+local mode) `users.yaml` are `10001:10001 0600`. The publisher assigns the numeric IDs directly;
+it does not create a host user or group for 10001.
+
+The runtime projection has only `CURRENT` and `generations/<64-lowercase-hex>/`. `CURRENT` selects
+one complete immutable generation. A successful configure, user mutation, restore, or explicit
+publish first blocks `CURRENT`, then verifies a new immutable generation, then makes it ready.
+The selected generation and up to two predecessor generations are retained; no operator edits a
+generation or `CURRENT` directly. A ready projection is usable only when its canonical revision is
+equal to the current canonical authentication root. If the runtime projection is blocked, missing,
+tampered, or unequal, `start`, `update --check-only`, `auth check`, and `doctor` fail closed before
+admission or Compose lifecycle work.
+
+The runtime directory must be an absolute canonical path, distinct from the canonical root, and
+must exactly equal `THT_AUTH_RUNTIME_ROOT` in the protected installation environment. The server
+profile and numeric UID/GID values are validated before any projected mutation or publication.
+
+The descriptor loader adds `compose.auth-runtime-projection.yaml` automatically when
+`runtimeProjection` is present; do not list that file under `overrides`. The automatic override
+mounts the runtime projection **read-only and core-only** at `/run/thothii-auth`; the canonical
+authentication root is never mounted. No other service receives that mount or
+`THT_AUTH_RUNTIME_PROJECTION_ROOT`. The example descriptor uses
+`/srv/example/thothii/auth-runtime` only as a replaceable path and contains no credential value.
+
+This source change is prepared and tested only: Project A has not been started. It does not
+authorize a raw Compose lifecycle launch, an Nginx change, legacy-stack change, or mutation of
+`/srv`. A later manual gate needs separate explicit authorization before applying any descriptor
+or runtime root to a server.
+
+### Status, repair, and safe evidence
+
+Use the root-operated installation command; retain only its small redacted JSON result:
+
+```sh
+sudo tht --installation "$INSTALLATION" auth status --json
+```
+
+`state: "ready"` and `equal: true` are required before a projected server can start. `state:
+"blocked"`, `equal: false`, or a command refusal means that the runtime projection is blocked or
+cannot be validated. Do not start the stack, inspect YAML, print an environment, or edit `CURRENT`
+or a generation. Confirm the protected canonical root is available, then republish it with:
+
+```sh
+sudo tht --installation "$INSTALLATION" auth publish
+sudo tht --installation "$INSTALLATION" auth status --json
+```
+
+`auth publish` reconstructs the selected immutable generation from the canonical root; it never
+uses an older runtime generation as authority. If publish fails, leave the projection blocked and
+escalate using the sanitized command result plus descriptor path and timestamp only. Do not attach
+passwords, hashes, YAML, raw environment output, `nginx -T`, or a secret-bearing diff to evidence.
+
+### Authentication restore
+
+An authentication-bearing restore first publishes a blocked selector, restores canonical
+authentication, and publishes a verified candidate generation before any restart. If candidate or
+recovery verification fails, the verified recovery checkpoint is republished when possible; an
+unverified result remains blocked and prevents start. A restore without authentication entries
+does not touch the runtime projection. This is in addition to the normal restore requirement that
+browser sessions and pending OIDC state are cleared.
+
 ## Firewall and network boundaries
 
 Set `THOTH_SERVER_BIND=127.0.0.1`. Permit inbound TCP 80/443 only to the TLS proxy; port 80 should
diff --git a/docs/plans/2026-08-20-psd-server-project-a-standalone.md b/docs/plans/2026-08-20-psd-server-project-a-standalone.md
index 6f2d1397..fd2e0882 100644
--- a/docs/plans/2026-08-20-psd-server-project-a-standalone.md
+++ b/docs/plans/2026-08-20-psd-server-project-a-standalone.md
@@ -251,6 +251,14 @@ Use `profile: server`, the exact new source root/env/auth root, workspace remote
 access, Project A override, and exactly one Git transport override. Do not include the public
 session-server overlay in Project A.
 
+For the projected local-auth descriptor, keep `authentication.configDirectory` as the canonical
+root and add `runtimeProjection` with a distinct absolute runtime directory plus numeric `uid: 10001`
+and `gid: 10001`. The descriptor loader includes the automatic runtime-projection override; do
+not list it manually under `overrides`. The canonical root stays `root:root 0700/0600`; the
+publisher owns the projection numerically as `10001:10001 0700/0600`. Only the projection is
+mounted read-only into core. Do not create a host user/group, edit `CURRENT` or `generations`, or
+apply these paths before the separately authorized start gate.
+
 **Step 4: Validate permissions and render**
 
 ```bash
@@ -274,6 +282,11 @@ Create a temporary mode-0600 password file using an echo-free prompt, then run:
 Remove the temporary input file after success and record that removal. Do not delete generated
 `auth.yaml` or `users.yaml`.
 
+Before the later start gate, run the redacted projected status command and require `ready` plus
+`equal: true`. A blocked result prevents start. `auth publish` is the only repair path: it rebuilds
+from canonical authentication, including after a candidate or recovery restore outcome; it never
+promotes a retained runtime generation on its own.
+
 ### Task 6: Build and start the clean stack
 
 **Files:**
diff --git a/docs/testing/authentication-manual-acceptance.md b/docs/testing/authentication-manual-acceptance.md
index c1a6ec51..116b3ace 100644
--- a/docs/testing/authentication-manual-acceptance.md
+++ b/docs/testing/authentication-manual-acceptance.md
@@ -35,6 +35,13 @@ than inferring a PASS.
 4. Confirm the exact direct `groups` claim for both identities and the mappings `TOT Users → user`
    and `TOT Admin → admin`. Confirm extra upstream groups are ignored without warning.
 
+5. For a projected Linux server, before any start gate, collect only the redacted result of
+   `sudo tht --installation "$INSTALLATION" auth status --json`. Record `state`, generation,
+   canonical revision, and `equal`; do not retain authentication YAML, user records, hashes, or
+   environment output. `ready` plus `equal: true` is required. A blocked or unequal result is a
+   fail-closed condition: do not start, and use `sudo tht --installation "$INSTALLATION" auth
+   publish` followed by the same status command only after the canonical root is available.
+
 ## Matrix
 
 | Scenario | Expected result |
@@ -56,6 +63,7 @@ than inferring a PASS.
 | Logout | Cookie expires and the server session is deleted. |
 | Provider outage | Live check reports `oidc_discovery_unreachable`; browser login fails closed without exposing credentials. |
 | Restore is completed | Sessions and OIDC state are absent; all users must reauthenticate. |
+| Projected authentication restore | Candidate generation and any recovery generation are published from the canonical root; a failed verification remains blocked and start is refused. |
 
 ## Status at Task 15
 
diff --git a/docs/testing/psd-server-project-a-manual.md b/docs/testing/psd-server-project-a-manual.md
index 47f7de02..786a1cd9 100644
--- a/docs/testing/psd-server-project-a-manual.md
+++ b/docs/testing/psd-server-project-a-manual.md
@@ -29,6 +29,13 @@ verdi installazione, workspace, DWH, Qdrant, Ollama e preprocessing.
 
 ## 1. Stato generale
 
+Prima del gate manuale di avvio, per una descriptor server con runtime projection eseguire solo il
+controllo redatto `sudo tht --installation "$INSTALLATION" auth status --json`. Il risultato deve
+dire `ready` ed `equal: true`. Se è `blocked`, mancante o diverso dal canonical root, non avviare:
+Sol può eseguire `sudo tht --installation "$INSTALLATION" auth publish` e ripetere il controllo,
+senza copiare YAML, hash, password, token o environment nel rapporto. Questo documento non
+autorizza l'avvio; Project A resta soggetto a un'esplicita autorizzazione separata.
+
 Eseguire:
 
 ```bash
diff --git a/scripts/auth-docs-smoke.sh b/scripts/auth-docs-smoke.sh
index 1801a164..1c9f16f3 100755
--- a/scripts/auth-docs-smoke.sh
+++ b/scripts/auth-docs-smoke.sh
@@ -157,4 +157,51 @@ if rg -n -i --pcre2 '(?:unmapped|additional|extra)[^.\r\n]{0,160}groups?[^.\r\n]
   exit 1
 fi
 
+# Projected server authentication documentation contract.
+projection_docs=(
+  "$root/docs/install/server.md"
+  "$root/docs/install/authentication-local.md"
+  "$root/docs/testing/authentication-manual-acceptance.md"
+  "$root/docs/testing/psd-server-project-a-manual.md"
+  "$root/docs/plans/2026-08-20-psd-server-project-a-standalone.md"
+  "$root/PROJECT_STATE.md"
+)
+projection_corpus=$(mktemp)
+trap 'rm -f "$corpus" "$projection_corpus"' EXIT
+cat "${projection_docs[@]}" >"$projection_corpus"
+projection_required=(
+  "canonical authentication root" "runtime projection" "CURRENT" "generations"
+  "root:root 0700/0600" "10001:10001 0700/0600"
+  "THT_AUTH_RUNTIME_ROOT"
+  "auth status --json" "auth publish"
+  "candidate or recovery" "Mac, Windows, and local direct-file authentication"
+  "explicit authorization"
+)
+for term in "${projection_required[@]}"; do
+  rg -Fqi "$term" "$projection_corpus" || {
+    echo "auth docs smoke: missing runtime-projection term: $term" >&2
+    exit 1
+  }
+done
+if rg -n -i --pcre2 "(?:useradd|groupadd)[^\n]{0,100}10001|10001[^\n]{0,100}(?:useradd|groupadd)" "$projection_corpus"; then
+  echo "auth docs smoke: runtime projection creates a host 10001 identity" >&2
+  exit 1
+fi
+if rg -n -i --pcre2 '(?:^|[.!?]\s+)(?:(?:mount|bind)\s+(?:the\s+)?(?:canonical authentication root|auth-canonical)\b[^\n]{0,120}(?:core|/run/thothii-auth)|(?:core|the core service)\s+(?:mounts?|binds?)\s+(?:the\s+)?(?:canonical authentication root|auth-canonical)\b)|auth-canonical[^\n]{0,120}:/run/thothii-auth' "$projection_corpus"; then
+  echo "auth docs smoke: canonical authentication is mounted into core" >&2
+  exit 1
+fi
+if rg -n -i --pcre2 '(?:(?:operators?\s+)?(?:may|can|should|must)\s+(?!not\b|never\b)(?:edit|write|modify|prune)|^\s*(?:sudo\s+)?(?:vi|vim|nano|sed|cp|mv|rm|tee|printf|echo)\b)[^\n]*(?:CURRENT|generations)' "$projection_corpus"; then
+  echo "auth docs smoke: runtime projection permits direct selector or generation edits" >&2
+  exit 1
+fi
+if rg -n -i --pcre2 '(?:^\s*(?:sudo\s+nginx\s+-T|(?:sudo\s+)?(?:printenv|env)(?:\s|$)|(?:sudo\s+)?(?:diff|cat|less|more|head|tail|yq)\s+[^\n]*(?:secret|auth\.yaml|users\.yaml))|(?:may|can|should|must)\s+(?!not\b|never\b)(?:dump|print|capture|attach|include|run)\b[^\n]*(?:password|auth\.yaml|users\.yaml|YAML|raw environment|nginx\s+-T|secret-bearing diff))' "$projection_corpus"; then
+  echo "auth docs smoke: runtime projection documents unsafe evidence collection" >&2
+  exit 1
+fi
+if rg -n -i --pcre2 'Project A (?:has been|was|is) started|legacy[- ]stack (?:has been|was|is) changed' "$projection_corpus"; then
+  echo "auth docs smoke: runtime projection claims live Project A or legacy mutation" >&2
+  exit 1
+fi
+
 echo "auth docs smoke: required terms and forbidden wording checks passed"
diff --git a/scripts/test-project-a-auth-runtime-projection.sh b/scripts/test-project-a-auth-runtime-projection.sh
new file mode 100755
index 00000000..8603ec75
--- /dev/null
+++ b/scripts/test-project-a-auth-runtime-projection.sh
@@ -0,0 +1,166 @@
+#!/usr/bin/env bash
+# Hermetic acceptance gate for the server authentication runtime projection.
+set -euo pipefail
+umask 077
+
+root="$(cd "$(dirname "$0")/.." && pwd -P)"
+forbidden_server_root="/$(printf '%s' srv)/"
+tmp_base="$(cd "${TMPDIR:-/tmp}" && pwd -P)"
+if [[ "$tmp_base/" == "$forbidden_server_root"* ]]; then
+  echo "runtime projection gate refuses a server temp root" >&2
+  exit 1
+fi
+if [[ -n "${DOCKER_HOST:-}" ]]; then
+  echo "runtime projection gate refuses a remote Docker endpoint" >&2
+  exit 1
+fi
+docker_context="$(docker context show)"
+docker_endpoint="$(docker context inspect "$docker_context" --format '{{(index .Endpoints "docker").Host}}')"
+if [[ "$docker_endpoint" != unix:///* ]]; then
+  echo "runtime projection gate requires a local Unix Docker endpoint" >&2
+  exit 1
+fi
+tmp="$(mktemp -d "$tmp_base/thoth-auth-runtime-projection.XXXXXX")"
+chmod 0700 "$tmp"
+mkdir -m 0700 "$tmp/go-mod" "$tmp/go-build"
+
+cleanup() {
+  local cleanup_status=0
+  if [[ -d "$tmp" ]]; then
+    docker run --rm --network none -v "$tmp:/cleanup" golang:1.26.5 \
+      sh -c 'find /cleanup -mindepth 1 -delete' >/dev/null 2>&1 || cleanup_status=$?
+    if ((cleanup_status == 0)); then
+      rmdir "$tmp" || cleanup_status=$?
+    fi
+  fi
+  return "$cleanup_status"
+}
+trap cleanup EXIT
+trap 'exit 129' HUP
+trap 'exit 130' INT
+trap 'exit 143' TERM
+
+project_name_flag="--project"-name
+compose_project_var='COMPOSE_PROJECT'_NAME
+network_flag="--net"work
+compose_pattern='docker[[:space:]]+com''pose'
+if rg -n -F -- "$forbidden_server_root" "$0"; then
+  echo "runtime projection gate must not reference a server path" >&2
+  exit 1
+fi
+if rg -n -- "$project_name_flag|$compose_project_var|${compose_pattern}[^[:cntrl:]]*(up|start)|docker[[:space:]]+network" "$0"; then
+  echo "runtime projection gate has a forbidden project, lifecycle, or network attachment" >&2
+  exit 1
+fi
+if rg -n -F -- "$network_flag" "$0" | rg -v -F -e "$network_flag none" -e "$network_flag=none"; then
+  echo "runtime projection gate permits only an explicitly isolated network option" >&2
+  exit 1
+fi
+if rg -n --pcre2 '^[[:space:]]*[A-Za-z_][A-Za-z0-9_]*(?:PASSWORD|SECRET|TOKEN|KEY)[A-Za-z_]*=' "$0"; then
+  echo "runtime projection gate declares a credential value" >&2
+  exit 1
+fi
+
+node24_source="$(
+  env -i PATH="$PATH" HOME="$HOME" npm_config_offline=true npm_config_userconfig=/dev/null \
+    npx -y -p node@24 node -p 'process.execPath'
+)"
+if [[ "$node24_source" != /* || ! -f "$node24_source" || ! -x "$node24_source" ]]; then
+  echo "runtime projection gate requires a cached Node 24 runtime" >&2
+  exit 1
+fi
+install -m 0755 "$node24_source" "$tmp/node24"
+
+run_case() {
+  local name="$1"
+  shift
+  local output="$tmp/$name.log"
+  if ! "$@" >"$output" 2>&1; then
+    echo "$name FAIL (test output suppressed and removed by cleanup)" >&2
+    return 1
+  fi
+  printf '%s PASS\n' "$name"
+}
+
+go_test() {
+  docker run --rm \
+    -v "$root:/work:ro" \
+    -v "$tmp/go-mod:/go/pkg/mod" \
+    -v "$tmp/go-build:/root/.cache/go-build" \
+    -w /work/tools/tht golang:1.26.5 go test "$@"
+}
+
+go_windows_compile() {
+  docker run --rm \
+    -v "$root:/work:ro" \
+    -v "$tmp/go-mod:/go/pkg/mod" \
+    -v "$tmp/go-build:/root/.cache/go-build" \
+    -w /work/tools/tht -e GOOS=windows -e GOARCH=amd64 golang:1.26.5 \
+    go test -c ./cmd/tht -o /tmp/tht.test.exe
+}
+
+go_darwin_compile() {
+  docker run --rm \
+    -v "$root:/work:ro" \
+    -v "$tmp/go-mod:/go/pkg/mod" \
+    -v "$tmp/go-build:/root/.cache/go-build" \
+    -w /work/tools/tht -e GOOS=darwin -e GOARCH=amd64 golang:1.26.5 \
+    go test -c ./cmd/tht -o /tmp/tht.test
+}
+
+backend_node24() {
+  docker run --rm --network none \
+    -e HOME=/tmp \
+    -v "$root:/work:ro" \
+    -v "$tmp/node24:/opt/node24:ro" \
+    -v "$root/backend/vitest.config.ts:/opt/vitest.config.ts:ro" \
+    -v "$root/backend/node_modules:/opt/node_modules:ro" \
+    -w /work/backend golang:1.26.5 \
+    /opt/node24 node_modules/vitest/vitest.mjs run --no-cache \
+      --config /opt/vitest.config.ts "$@"
+}
+
+backend_in_flight() {
+  backend_node24 test/auth-runtime-projection.test.ts \
+    -t 'in-flight snapshot authenticates A after selection B and deletion A'
+}
+
+backend_direct_file() {
+  backend_node24 test/config.test.ts \
+    -t 'keeps the direct auth-file provider when the runtime projection environment is absent'
+}
+
+mac_windows_direct_file() {
+  go_windows_compile
+  go_darwin_compile
+  backend_direct_file
+}
+
+run_case descriptor_requires_server_uid_gid_and_matching_env \
+  go_test ./internal/config -run 'TestLoadAcceptsServerRuntimeProjectionAndPlacesAutomaticOverrideBeforeCurrentImage|TestLoadRejectsInvalidRuntimeProjection|TestLoadRejectsRuntimeProjectionEnvironmentWithoutDescriptor' -count=1
+run_case compose_mount_is_core_only_read_only_and_noncanonical \
+  bash "$root/scripts/test-auth-runtime-projection-compose.sh"
+run_case local_initial_configure_publishes_equal_ready \
+  go_test ./internal/setup ./internal/authconfig -run 'TestRunConfigureOnlyPublishesInitialProjectedServerAuthentication|TestRunProjectedMutationPublishesExactLocalAndOIDCSnapshots/local' -count=1
+run_case oidc_initial_configure_publishes_equal_ready \
+  go_test ./internal/authconfig -run 'TestRunProjectedMutationPublishesExactLocalAndOIDCSnapshots/oidc' -count=1
+run_case every_user_mutation_blocks_then_publishes \
+  go_test ./internal/authconfig -run 'TestProjectedAuthMutatorsBlockBeforeCanonicalWriteAndPublishOnlyEqualSnapshots' -count=1
+run_case publish_repairs_blocked_from_canonical \
+  go_test ./internal/authconfig -run 'TestPublishProjectedCanonicalRepairsBlockedStateFromCanonicalOnly|TestProjectedAuthPublishStatusAndCheckFailClosed' -count=1
+run_case start_and_doctor_fail_closed_for_missing_blocked_tampered_or_divergent \
+  go_test ./internal/authprojection ./internal/authconfig ./internal/service ./internal/doctor ./cmd/tht -run 'TestInspectRejectsMissingBlockedMalformedAndTamperedCurrent|TestRequireRuntimeAuthProjectionReadyRejectsMissingBlockedAndDivergentStates|TestStartRefusesProjectedAuthenticationBeforeComposeWhenNotReady|TestRunReportsOneSanitizedRuntimeAuthProjectionFailureBeforeCompose|TestRunUpdateCheckOnlyRefusesProjectedAuthenticationBeforeCompose' -count=1
+run_case backend_authenticates_from_one_immutable_generation_after_previous_gc backend_in_flight
+run_case auth_restore_publishes_candidate \
+  go_test ./internal/backup -run 'TestRestoreAuthBearingArchiveBlocksBeforeWritePublishesBeforeRestart' -count=1
+run_case failed_candidate_verification_republishes_checkpoint \
+  go_test ./internal/backup -run 'TestRestoreAuthVerificationFailuresRepublishCheckpointBeforeRecoveryRestart' -count=1
+run_case failed_recovery_publish_remains_blocked \
+  go_test ./internal/backup -run 'TestRestoreAuthCandidatePublicationFailureRecoversThenStaysBlockedWithoutRestart' -count=1
+run_case non_auth_restore_never_touches_projection \
+  go_test ./internal/backup -run 'TestRestoreNonAuthArchiveNeverBeginsProjection' -count=1
+run_case mac_windows_local_regression mac_windows_direct_file
+run_case secret_redaction \
+  go_test ./internal/authconfig -run 'TestProjectionCoordinatorErrorsAndLogsNeverContainSyntheticPasswordsOrHashes' -count=1
+
+echo "runtime authentication projection acceptance gate passed."
diff --git a/scripts/test-verify-workspace-install-docs.sh b/scripts/test-verify-workspace-install-docs.sh
index 1a49ae26..599450bb 100755
--- a/scripts/test-verify-workspace-install-docs.sh
+++ b/scripts/test-verify-workspace-install-docs.sh
@@ -1106,4 +1106,89 @@ if (( negative_failures != 0 )); then
   exit 1
 fi
 
+# Projected server authentication documents must preserve the root-only canonical/runtime split.
+projection_example="$root/docs/install/examples/thothii-installation.server.yaml"
+for required in \
+  'runtimeProjection:' \
+  'directory: "/srv/example/thothii/auth-runtime"' \
+  'uid: 10001' \
+  'gid: 10001'; do
+  grep -Fq -- "$required" "$projection_example" || {
+    echo "server authentication projection example lacks: $required" >&2
+    exit 1
+  }
+done
+if rg -n -i --pcre2 '(?:password|secret)[[:space:]]*:[[:space:]]*[^<#[:space:]]+' "$projection_example"; then
+  echo "server authentication projection example contains a credential value" >&2
+  exit 1
+fi
+
+projection_docs=(
+  "$root/docs/install/server.md"
+  "$root/docs/install/authentication-local.md"
+  "$root/docs/testing/authentication-manual-acceptance.md"
+  "$root/docs/testing/psd-server-project-a-manual.md"
+  "$root/docs/plans/2026-08-20-psd-server-project-a-standalone.md"
+  "$root/PROJECT_STATE.md"
+)
+projection_corpus="$negative_root/projection-corpus.md"
+cat "${projection_docs[@]}" >"$projection_corpus"
+
+projection_documentation_is_safe() {
+  local corpus="$1"
+  if rg -q -i --pcre2 '(?:useradd|groupadd)[^\n]{0,100}10001|10001[^\n]{0,100}(?:useradd|groupadd)' "$corpus"; then
+    return 1
+  fi
+  if rg -q -i --pcre2 '(?:^|[.!?]\s+)(?:(?:mount|bind)\s+(?:the\s+)?(?:canonical authentication root|auth-canonical)\b[^\n]{0,120}(?:core|/run/thothii-auth)|(?:core|the core service)\s+(?:mounts?|binds?)\s+(?:the\s+)?(?:canonical authentication root|auth-canonical)\b)|auth-canonical[^\n]{0,120}:/run/thothii-auth' "$corpus"; then
+    return 1
+  fi
+  if rg -q -i --pcre2 '(?:(?:operators?\s+)?(?:may|can|should|must)\s+(?!not\b|never\b)(?:edit|write|modify|prune)|^\s*(?:sudo\s+)?(?:vi|vim|nano|sed|cp|mv|rm|tee|printf|echo)\b)[^\n]*(?:CURRENT|generations)' "$corpus"; then
+    return 1
+  fi
+  if rg -q -i --pcre2 '(?:^\s*(?:sudo\s+nginx\s+-T|(?:sudo\s+)?(?:printenv|env)(?:\s|$)|(?:sudo\s+)?(?:diff|cat|less|more|head|tail|yq)\s+[^\n]*(?:secret|auth\.yaml|users\.yaml))|(?:may|can|should|must)\s+(?!not\b|never\b)(?:dump|print|capture|attach|include|run)\b[^\n]*(?:password|auth\.yaml|users\.yaml|YAML|raw environment|nginx\s+-T|secret-bearing diff))' "$corpus"; then
+    return 1
+  fi
+  if rg -q -i --pcre2 'Project A (?:has been|was|is) started|legacy[- ]stack (?:has been|was|is) changed' "$corpus"; then
+    return 1
+  fi
+  return 0
+}
+
+for required in \
+  'canonical authentication root' \
+  'read-only and core-only' \
+  'candidate or recovery' \
+  'runtime projection is blocked' \
+  'Project A has not been started'; do
+  if ! rg -Fqi -- "$required" "${projection_docs[@]}"; then
+    echo "server authentication projection documentation lacks: $required" >&2
+    exit 1
+  fi
+done
+if ! projection_documentation_is_safe "$projection_corpus"; then
+  echo "server authentication projection documentation contains an unsafe instruction or claim" >&2
+  exit 1
+fi
+
+while IFS='|' read -r fixture_name payload; do
+  fixture="$negative_root/projection-$fixture_name.md"
+  cp "$projection_corpus" "$fixture"
+  printf '\n%s\n' "$payload" >>"$fixture"
+  if projection_documentation_is_safe "$fixture"; then
+    echo "server authentication projection documentation accepted unsafe fixture: $fixture_name" >&2
+    exit 1
+  fi
+done <<'PROJECTION_NEGATIVE_FIXTURES'
+host-identity|sudo useradd --system --uid 10001 thothii
+canonical-core-mount|Mount the canonical authentication root into core at /run/thothii-auth.
+core-subject-canonical-mount|Core mounts the canonical authentication root at /run/thothii-auth.
+direct-runtime-edit|Operators may edit CURRENT and prune generations directly.
+yaml-dump|Operators may dump auth.yaml and users.yaml into evidence.
+nginx-dump|sudo nginx -T
+raw-environment|printenv
+sudo-raw-environment|sudo printenv
+secret-diff|sudo diff auth.yaml auth.yaml.previous
+live-claim|Project A has been started.
+PROJECTION_NEGATIVE_FIXTURES
+
 echo "unsafe installation-document fixtures rejected passed"