fix(security): fail closed on unavailable dependency review

.github/workflows/security-scan.yml

@@ -16,10 +16,14 @@
 # pull_request workflows upload to refs/pull/N/merge, so no single ref ever holds
 # all tools. Bundling at the workflow/check level is ref-independent.
 #
-# NOTE on dependency-review: dependency graph can be unavailable on some repos.
-# Treat that as "not enforceable here" instead of making the required workflow
-# unsatisfiable; keep medium-or-higher dependency findings hard-failing where the
-# API is supported.
+# NOTE on dependency-review: unavailable evidence is not a clean result. Only
+# an exact base/head comparison returning HTTP 200 with curl exit 0 may reach
+# the pinned hard gate. Named refs, `.`/`..` repository segments, and other
+# malformed identity fail closed before the network call and are not echoed.
+# Curl's `000` sentinel is unavailable evidence. HTTP 403/404, empty or
+# malformed status, or transport failure also fails closed. Diagnostics
+# record allowlisted visibility; they never print the response body. See
+# docs/doctoring/dependency-review-fail-closed.md.
 #
 # NOTE on trivy-fs: it scans the whole repo, so a pre-existing FIXABLE
 # MEDIUM/HIGH/CRITICAL finding blocks every PR in that repo until it is fixed.
@@ -257,9 +261,11 @@ jobs:
       contents: read
       pull-requests: read
     steps:
-      - name: Checkout
+      - name: Checkout exact head
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
         with:
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.sha }}
           persist-credentials: false
       - name: Check dependency review support
         id: dependency_review_support
@@ -268,36 +274,53 @@ jobs:
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
           HEAD_SHA: ${{ github.event.pull_request.head.sha }}
           REPOSITORY: ${{ github.repository }}
+          REPOSITORY_VISIBILITY: ${{ github.event.repository.visibility }}
         run: |
           set -euo pipefail
 
           api_url="${GITHUB_API_URL:-https://api.github.com}"
-          response_file="$(mktemp)"
+          case "${REPOSITORY_VISIBILITY}" in
+            public|private|internal) visibility="${REPOSITORY_VISIBILITY}" ;;
+            *) visibility="unknown" ;;
+          esac
+          revision_pattern='^[0-9a-fA-F]{40}$|^[0-9a-fA-F]{64}$'
+          repository_pattern='^[A-Za-z0-9_.-]+/[A-Za-z0-9_.-]+$'
+          repository_owner="${REPOSITORY%%/*}"
+          repository_name="${REPOSITORY#*/}"
+          if ! [[ "${BASE_SHA}" =~ $revision_pattern ]] || ! [[ "${HEAD_SHA}" =~ $revision_pattern ]]; then
+            echo "::error::Dependency review evidence unavailable for the allowlisted repository (visibility ${visibility}): HTTP unavailable; curl exit uncalled. Malformed revision. Supply the pull request's exact 40- or 64-character hex base and head SHAs, then rerun. Named refs are not evidence. Failing closed."
+            exit 1
+          fi
+          if ! [[ "${REPOSITORY}" =~ $repository_pattern ]] || [ "${repository_owner}" = "." ] || [ "${repository_owner}" = ".." ] || [ "${repository_name}" = "." ] || [ "${repository_name}" = ".." ]; then
+            echo "::error::Dependency review evidence unavailable (visibility ${visibility}): HTTP unavailable; curl exit uncalled. Malformed repository. Use the canonical owner/name without . or .. path segments, then rerun. Failing closed."
+            exit 1
+          fi
+          set +e
           status="$(
-            curl -fsS -o "$response_file" -w '%{http_code}' \
+            curl -sS --connect-timeout 10 --max-time 30 \
+              -o /dev/null \
+              -w '%{http_code}' \
               -H "Accept: application/vnd.github+json" \
               -H "Authorization: Bearer ${GH_TOKEN}" \
               -H "X-GitHub-Api-Version: 2022-11-28" \
-              "${api_url}/repos/${REPOSITORY}/dependency-graph/compare/${BASE_SHA}...${HEAD_SHA}" \
-              || true
+              "${api_url}/repos/${REPOSITORY}/dependency-graph/compare/${BASE_SHA}...${HEAD_SHA}"
           )"
+          curl_status=$?
+          set -e
 
-          if [ "$status" = "200" ]; then
-            echo "supported=true" >>"$GITHUB_OUTPUT"
-            exit 0
-          fi
+          case "$status" in
+            000|"") http_status="unavailable" ;;
+            [0-9][0-9][0-9]) http_status="$status" ;;
+            *) http_status="malformed" ;;
+          esac
 
-          if [ "$status" = "403" ] || [ "$status" = "404" ]; then
-            echo "::warning::Dependency review is unavailable for ${REPOSITORY}; skipping dependency-review hard gate."
-            echo "supported=false" >>"$GITHUB_OUTPUT"
-            exit 0
+          if [ "$curl_status" -ne 0 ] || [ "$http_status" != "200" ]; then
+            echo "::error::Dependency review evidence unavailable for ${REPOSITORY} (visibility ${visibility}) at exact base ${BASE_SHA} and head ${HEAD_SHA}: HTTP ${http_status}; curl exit ${curl_status}. Verify dependency-graph/security configuration and GitHub service behavior, then rerun. Failing closed."
+            exit 1
           fi
 
-          echo "::error::Dependency review support check failed with HTTP ${status}."
-          cat "$response_file"
-          exit 1
+          echo "supported=true" >>"$GITHUB_OUTPUT"
       - name: Dependency review
-        if: steps.dependency_review_support.outputs.supported == 'true'
         uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0
         with:
           fail-on-severity: moderate

AGENTS.md

@@ -5,3 +5,4 @@
 
 Materialize accepts only exact SHA-256 pins or a bounded relative `-r` include (no `.`/`..`); a lone `--require-hashes` directive is not trust evidence. See [`docs/doctoring/hourly-nvidia-nim-autofix.md`](docs/doctoring/hourly-nvidia-nim-autofix.md).
 Conflict-scope roots fail closed when the immediate parent directory is a symbolic link.
+Dependency-review unavailability fails closed; diagnostics include allowlisted repository visibility. See [`docs/doctoring/dependency-review-fail-closed.md`](docs/doctoring/dependency-review-fail-closed.md).

ARCHITECTURE.md

@@ -90,6 +90,29 @@ sequenceDiagram
 - Rust remains the psychometric arithmetic owner. Repair never substitutes
   Python for scoring math.
 
+## Dependency-review evidence
+
+The central `Security Scan` job treats GitHub's exact `BASE_SHA...HEAD_SHA`
+comparison as a hard supply-chain evidence boundary. Only transport exit `0`
+plus HTTP `200` may reach the immutably pinned dependency-review action. A
+`403`, `404`, timeout, truncated transfer, or malformed status fails closed
+and records allowlisted repository visibility with the exact revisions. Other
+scanners are complementary; they are not substitutes.
+
+```mermaid
+flowchart TD
+  Probe["Exact base/head compare probe"]
+  Transport{"curl exit 0 and HTTP 200?"}
+  Action["Pinned dependency-review action"]
+  Fail["Fail closed with repo, visibility, SHAs, status"]
+
+  Probe --> Transport
+  Transport -->|"yes"| Action
+  Transport -->|"no"| Fail
+```
+
+See [`docs/doctoring/dependency-review-fail-closed.md`](docs/doctoring/dependency-review-fail-closed.md).
+
 ## Quality gates
 
 `scripts/ci/` ships with 100% statement/branch coverage and 100% docstrings.

CHANGELOG.md

@@ -39,6 +39,7 @@ Semantic Versioning where the repository publishes a release.
 
 ### Security
 
+- Fail closed when GitHub dependency-review evidence is unavailable (HTTP 403/404, empty or malformed status, curl `000`, or transport failure, including curl exit 18 with a printed 200) instead of treating those outcomes as a clean skip; reject empty/named/`../` identity before the compare call, record allowlisted visibility with the exact base and head SHAs after a real probe, and never print the API body.
 - Reject `.github/` and `scripts/ci/` from review-thread-derived autofix path authority so an untrusted inline reviewer cannot authorize the write-capable repair agent to modify workflows, CODEOWNERS, actions, scheduler code, or CI helpers that govern its own control plane.
 - Require the model-write snapshot and exact-path allowlist to remain outside the pull-request worktree, checking both absolute and resolved locations so repository-local controls and outside-looking symlinks resolving into the repository fail closed before they can authorize or verify model changes.
 - Snapshot the complete pre-model worktree for ordinary and conflict repair and reject every model-caused created, deleted, modified, mode-changed, retargeted, ignored, dangling, directory-backed, external-link, metadata-race, or out-of-scope path before staging or push.

docs/doctoring/dependency-review-fail-closed.md

@@ -0,0 +1,57 @@
+# Dependency review fail-closed operations
+
+Status: `active_pr` until the matching workflow and regression contract are present on protected `main`; thereafter `implemented_on_protected_main`.
+
+## Decision
+
+Dependency review is a hard supply-chain gate. The central workflow accepts only HTTP `200` from GitHub's exact `BASE_SHA...HEAD_SHA` comparison, with curl transport exit `0`, before invoking the immutably pinned dependency-review action. A `403`, `404`, empty or malformed status, timeout, transport failure, truncated exchange, or other unexpected outcome is unavailable evidence and fails closed.
+
+The support probe validates identity before any network call. Both revisions must be 40- or 64-character hex object ids; named refs are not evidence. The repository must be canonical `owner/name` without `.` or `..` path segments (the special `.github` repository name remains legal). Malformed identity fails closed with HTTP `unavailable` and curl exit `uncalled` and does not echo the raw values.
+
+The probe has a 10-second connection limit and 30-second total limit. It preserves curl's transport exit code separately from the bounded HTTP status and requires transport exit `0` plus exact HTTP `200`. Curl's `000` sentinel is unavailable evidence. It discards the response body and logs only repository identity, allowlisted visibility (`public`, `private`, `internal`, or `unknown`), exact base/head revisions, the normalized HTTP status, and the numeric transport exit. Credentials, response bodies, and raw untrusted visibility strings are never diagnostic output. After a successful probe the pinned action is not independently skippable.
+
+RFC 9110 §15.3.1 defines `200` as a completed successful representation, not as a status that can be inferred after a truncated transfer (Fielding et al., 2022). NIST SP 800-53 Rev. 5 RA-5 and SA-12 require that vulnerability and supply-chain evidence be obtained, not assumed absent (National Institute of Standards and Technology, 2020). SLSA v1.0 likewise treats missing provenance as unverified rather than passing (SLSA, 2023). An HTTP `403` or `404` is therefore unavailable evidence, not a clean skip.
+
+## Identity and authority
+
+The dependency-review job checks out the pull request's explicit head repository and immutable head SHA with persisted credentials disabled. The API comparison independently binds the event's exact base and head revisions. The job retains `contents: read` and `pull-requests: read`; it receives no write, OIDC, model, release, package, or deployment authority.
+
+Checks, status contexts, review submissions, and merge authorization remain separate evidence classes. OSV, Trivy, CodeQL, Semgrep, Secret Scan, Scorecard, and Dependabot are complementary controls and are not semantic substitutes for dependency review.
+
+## Failure classification and remediation
+
+- Transport exit `0` plus HTTP `200` after validated identity: proceed to the pinned dependency-review action.
+- Malformed revision or repository: fail before curl with HTTP `unavailable` and curl exit `uncalled`. Do not echo the raw identity.
+- Any other result: fail the job and retain exact repository, allowlisted visibility, base/head, status, and transport-exit evidence. An HTTP `200` emitted by a failed or partial transfer, and curl's `000` sentinel, are unavailable evidence. Do not infer a root cause from HTTP `403` or `404`.
+- Public repository failure: verify dependency graph and security configuration, organization policy, token read access, and GitHub service health.
+- Private or internal exception: require a separately reviewed organization policy with explicit entitlement evidence and compensating controls. Never infer `not-applicable` from an unavailable response.
+
+Retries are operator-initiated only after the capability or service condition changes. Do not rerun unchanged evidence repeatedly and do not convert an unavailable endpoint into a green skip.
+
+## Acceptance and rollback
+
+Acceptance requires the permanent queue contract to reject the former `supported=false` path, require bounded probing and discarded bodies, require exact-head checkout, and prove that only `200` with curl exit `0` reaches the action. Exact-head CI/security evidence, current review, protected integration, and a real protected-main consumer run remain required.
+
+Do not close ContextualWisdomLab/.github#810 until a protected-main public-repository consumer run (for example ContextualWisdomLab/EgressWeave) proves a non-200 or failed-transfer comparison cannot produce a green Dependency Review gate.
+
+Rollback requires an independently reviewed revert and fresh exact-head evidence. A rollback must not restore the `403`/`404` success path or print an API response body.
+
+## References
+
+Fielding, R., Nottingham, M., & Reschke, J. (Eds.). (2022). *HTTP semantics*
+(RFC 9110). Internet Engineering Task Force. https://doi.org/10.17487/RFC9110
+
+GitHub. (n.d.). *Dependency review*. GitHub Docs. Retrieved August 16, 2026, from https://docs.github.com/en/code-security/concepts/supply-chain-security/dependency-review
+
+GitHub. (n.d.). *REST API endpoints for dependency review*. GitHub Docs. Retrieved August 16, 2026, from https://docs.github.com/en/rest/dependency-graph/dependency-review
+
+GitHub. (n.d.). *Dependency graph*. GitHub Docs. Retrieved August 16, 2026, from https://docs.github.com/en/code-security/concepts/supply-chain-security/dependency-graph
+
+GitHub. (n.d.). *Webhook events and payloads*. GitHub Docs. Retrieved August 16, 2026, from https://docs.github.com/en/webhooks/webhook-events-and-payloads#repository
+
+National Institute of Standards and Technology. (2020). *Security and
+privacy controls for information systems and organizations* (NIST SP
+800-53 Rev. 5). https://doi.org/10.6028/NIST.SP.800-53r5
+
+SLSA. (2023). *SLSA v1.0: Supply-chain Levels for Software Artifacts*.
+Open Source Security Foundation. https://slsa.dev/spec/v1.0/