diff --git a/.yamllint.yml b/.yamllint.yml
new file mode 100644
index 0000000..ce0e69d
--- /dev/null
+++ b/.yamllint.yml
@@ -0,0 +1,13 @@
+extends: default
+
+rules:
+  comments:
+    min-spaces-from-content: 1
+  document-start: disable
+  indentation: disable
+  # Checkpoint patterns embed jq expressions that can be long single-line strings;
+  # raise the limit to accommodate them without splitting and risking regex changes.
+  line-length:
+    max: 300
+  truthy:
+    allowed-values: ['true', 'false', 'on']
diff --git a/skills/github-release/SKILL.md b/skills/github-release/SKILL.md
index 4aed907..b399c15 100644
--- a/skills/github-release/SKILL.md
+++ b/skills/github-release/SKILL.md
@@ -26,12 +26,12 @@ These commands are blocked by hooks. GitHub immutable releases (GA Oct 2025) mak
 2. **Determine next version** — based on conventional commits or user input (major/minor/patch)
 3. **Bump version files** — update all ecosystem-specific version files consistently
 4. **Update CHANGELOG.md** — add release section with date and changes
-5. **Create release branch and PR** — `release/vX.Y.Z` branch, open PR for review
-6. **After PR merge** — create signed annotated tag: `git tag -s vX.Y.Z -m "vX.Y.Z"`
+5. **Create release branch and PR** — `release/vX.Y.Z` branch, open PR for review (always use a PR; branch protection typically blocks direct pushes anyway, and CI gets one last chance to validate)
+6. **After PR merge** — `git checkout main && git pull`, then tag `main`'s HEAD: `git tag -s vX.Y.Z -m "vX.Y.Z"`. Tag from `main`, not from the `release/vX.Y.Z` branch tip — see `references/release-process.md` Phase 3.
 7. **Push tag** — `git push origin vX.Y.Z` triggers CI workflow
 8. **CI publishes release** — with artifacts, checksums, and auto-generated release notes
-9. **Overhaul release description** — rewrite the auto-generated notes into a narrative summary in a local file, then apply with `gh release edit vX.Y.Z --notes-file notes.md`. Use `--notes-file` (not `--notes "..."`) so multi-line Markdown doesn't trip over shell quoting.
-10. **Do NOT re-run the release workflow after step 9** — many release workflows (e.g. `softprops/action-gh-release`) regenerate the body from the commit log on every run and will overwrite the manual overhaul. If a downstream job (TER publish, artifact upload) needs a retry, use a dedicated dispatcher workflow (see `references/ter-republish.md` for the TYPO3 pattern).
+9. **Overhaul release description** — rewrite auto-generated notes into a narrative summary, apply with `gh release edit vX.Y.Z --notes-file notes.md` (use `--notes-file`, not `--notes "..."`, to avoid shell quoting issues with multi-line Markdown)
+10. **Do NOT re-run the release workflow after step 9** — many workflows (e.g. `softprops/action-gh-release`) regenerate the body each run and will overwrite the overhaul. For downstream retries (TER publish, artifact upload), use a dedicated dispatcher workflow — see `references/ter-republish.md`.
 
 ## Commands
 
@@ -50,6 +50,6 @@ These commands are blocked by hooks. GitHub immutable releases (GA Oct 2025) mak
 - `references/ecosystem-detection.md` — version file patterns per ecosystem
 - `references/immutable-releases.md` — GitHub immutable releases and tag burning
 - `references/supply-chain-security.md` — SLSA, Sigstore, SBOMs, attestations
-- `references/recovery-procedures.md` — burned tags, stuck drafts, version drift, release-body clobbering after manual overhaul, mis-tagged SemVer releases, branch-protection gotchas
-- `references/ter-republish.md` — TYPO3 Extension Repository re-publish patterns (workflow_dispatch-only caller, codepoint-safe comment truncation, v-prefix + bare-version tag compatibility)
+- `references/recovery-procedures.md` — burned tags, stuck drafts, version drift, release-body clobbering, mis-tagged SemVer releases, branch-protection gotchas
+- `references/ter-republish.md` — TYPO3 Extension Repository re-publish patterns
 - `references/ci-workflow-templates.md` — CI workflow structure and templates
diff --git a/skills/github-release/checkpoints.yaml b/skills/github-release/checkpoints.yaml
index 2aa6d93..43e7955 100644
--- a/skills/github-release/checkpoints.yaml
+++ b/skills/github-release/checkpoints.yaml
@@ -88,14 +88,18 @@ mechanical:
 
   - id: GR-10
     type: command
-    pattern: "gh release view --json assets --jq -e '[.assets[].name] as $n | ($n|any(test(\"\\\\.bundle$\"))) or ($n|any(test(\"\\\\.sig$\")) and ($n|any(test(\"\\\\.pem$\"))))' >/dev/null 2>&1"
+    pattern: "gh release view --json assets --jq -e '[.assets[].name] as $n | ($n|any(test(\"\\\\.sigstore\\\\.json$\"))) or ($n|any(test(\"\\\\.sigstore$\"))) or ($n|any(test(\"\\\\.bundle$\"))) or ($n|any(test(\"\\\\.sig$\")) and ($n|any(test(\"\\\\.pem$\"))))' >/dev/null 2>&1"
     severity: warning
     desc: >-
-      Latest published release should have cosign signature artefacts:
-      either a modern `.bundle` (Sigstore bundle), or BOTH a detached `.sig`
-      and matching `.pem` certificate (used by netresearch/skill-repo-skill
-      release workflow). A lone `.sig` or lone `.pem` is incomplete and
-      fails. `jq -e` ensures the boolean is reflected in the exit code.
+      Latest published release should have cosign signature artefacts.
+      Accepted (in priority order): `.sigstore.json` (preferred — on the
+      OSSF Scorecard Signed-Releases allowlist), `.sigstore` (also on the
+      Scorecard allowlist), `.bundle` (legacy cosign default — bytes are
+      identical to `.sigstore.json`, only the filename differs), or BOTH
+      a detached `.sig` and matching `.pem` certificate (used by
+      netresearch/skill-repo-skill release workflow). A lone `.sig` or
+      lone `.pem` is incomplete and fails. `jq -e` ensures the boolean
+      is reflected in the exit code.
 
   - id: GR-11
     type: command
diff --git a/skills/github-release/evals/evals.json b/skills/github-release/evals/evals.json
index d19cacd..1791e19 100644
--- a/skills/github-release/evals/evals.json
+++ b/skills/github-release/evals/evals.json
@@ -752,14 +752,15 @@
     {
       "id": 28,
       "prompt": "Is the latest release signed with cosign?",
-      "expected_output": "Query the latest GitHub release assets. Check for cosign signature bundles (.bundle files) and attestation artifacts. Report signing status. If missing, recommend adding cosign signing to the release workflow.",
+      "expected_output": "Query the latest GitHub release assets. Check for cosign signature bundles (preferred extension `.sigstore.json`, with `.bundle` accepted as legacy) and attestation artifacts. Report signing status. If missing or using only `.bundle`, recommend `.sigstore.json` for OSSF Scorecard Signed-Releases compliance.",
       "expectations": [
         "Queries release assets",
-        "Checks for .bundle files",
+        "Checks for .sigstore.json or .bundle signature files",
         "Reports signing status",
         "Recommends fix if missing",
+        "Notes OSSF Scorecard requires .sigstore.json (or another allowlisted extension) — .bundle alone scores 0/10",
         "Does NOT: Assume signing exists without checking",
-        "Does NOT: Skip bundle file inspection"
+        "Does NOT: Skip signature file inspection"
       ],
       "assertions": [
         {
diff --git a/skills/github-release/references/release-process.md b/skills/github-release/references/release-process.md
index b0a2903..10c8733 100644
--- a/skills/github-release/references/release-process.md
+++ b/skills/github-release/references/release-process.md
@@ -45,15 +45,25 @@ The hooks in this repository block `gh release create` and `gh release delete` t
 After the PR is merged into main:
 
 ```
-1. git checkout main && git pull
-2. git tag -s vX.Y.Z -m "vX.Y.Z"
-3. git push origin vX.Y.Z
+1. git checkout main && git pull          # advance to main's post-merge HEAD
+2. git tag -s vX.Y.Z -m "vX.Y.Z"          # tags main's HEAD
+3. git push origin vX.Y.Z                 # release orchestrator picks it up
 ```
 
 The tag MUST be:
 - **Annotated** (`-a` or `-s`), never lightweight
 - **Signed** (`-s` for GPG/SSH signing) — required for SLSA L1+
-- **On the merge commit** — not on the branch, not on an older commit
+- **On `main`'s HEAD after the PR merges** — not on the `release/vX.Y.Z` branch tip, not on an older commit
+
+**Why `main`'s post-merge HEAD and not the release branch tip:** depending on the project's merge strategy, `main`'s HEAD after merge is one of:
+
+- The original branch-tip commit, if the PR was fast-forwarded;
+- A new squash commit, if the PR was squash-merged;
+- A new merge commit, if the PR was merge-committed.
+
+The tag must point to whatever is now the tip of `main` — that is what consumers will check out, what CI will build artifacts from, and what shows up as "the release commit" on the GitHub release page. With squash- or merge-commit strategies, the `release/vX.Y.Z` branch tip is *not* on `main`'s first-parent history, so tagging it produces a tag that doesn't correspond to any commit on `main`.
+
+In practice: do NOT `git tag` from inside the worktree on the `release/vX.Y.Z` branch. Switch to `main`, pull, then tag — the steps above already enforce this order.
 
 ### Phase 4: CI Release Workflow
 
diff --git a/skills/github-release/references/supply-chain-security.md b/skills/github-release/references/supply-chain-security.md
index 0cd32e9..d02f7eb 100644
--- a/skills/github-release/references/supply-chain-security.md
+++ b/skills/github-release/references/supply-chain-security.md
@@ -35,15 +35,51 @@ GitHub Actions natively supports SLSA L1 via `actions/attest-build-provenance`.
 
 ```yaml
 - uses: sigstore/cosign-installer@v3
-- run: cosign sign-blob --yes --oidc-issuer https://token.actions.githubusercontent.com artifact.tar.gz
+- run: |
+    cosign sign-blob --yes \
+      --oidc-issuer https://token.actions.githubusercontent.com \
+      --bundle artifact.tar.gz.sigstore.json \
+      artifact.tar.gz
 ```
 
+### Output extension matters for OSSF Scorecard
+
+**Use `.sigstore.json` for the cosign bundle output, NOT cosign's default `.bundle`.**
+
+OSSF Scorecard's [Signed-Releases](https://github.com/ossf/scorecard/blob/main/docs/checks.md#signed-releases) check pattern-matches release-asset filenames against a fixed allowlist of signature extensions:
+
+- `.sig`
+- `.asc`
+- `.minisig`
+- `.sigstore`
+- `.sigstore.json`
+- `.intoto.jsonl`
+
+The `.bundle` extension that `cosign sign-blob --bundle` writes by default is **not** on that list, so cosign-signed releases that use `.bundle` are reported as unsigned (`Signed-Releases` score `0/10`).
+
+**The bytes inside the file are identical** — cosign's bundle format IS the Sigstore bundle JSON. Only the filename matters for tooling detection. `cosign verify-blob --bundle file.sigstore.json` works exactly the same as `--bundle file.bundle`.
+
+**Concrete fix in a workflow:**
+
+```yaml
+# Wrong — Scorecard sees this as unsigned
+cosign sign-blob --yes "$file" --bundle "${file}.bundle"
+
+# Right — Scorecard recognizes this as signed
+cosign sign-blob --yes "$file" --bundle "${file}.sigstore.json"
+```
+
+**Past releases cannot be retroactively fixed.** GitHub releases are immutable once assets are attached, so renaming or replacing assets on already-published releases is not possible. Only future releases benefit from the fix. Scorecard averages the Signed-Releases score over the **last 4 releases**, so the score climbs gradually as new releases ship.
+
+Reference upstream change for the netresearch shared workflows: [netresearch/typo3-ci-workflows#84](https://github.com/netresearch/typo3-ci-workflows/pull/84) — applied to both `release.yml` and `release-typo3-extension.yml`.
+
 ### Verification
 
 ```bash
 cosign verify-blob \
   --certificate-oidc-issuer https://token.actions.githubusercontent.com \
   --certificate-identity-regexp "github.com/org/repo" \
+  --bundle artifact.tar.gz.sigstore.json \
   artifact.tar.gz
 ```
 
diff --git a/skills/github-release/templates/release-generic.yml b/skills/github-release/templates/release-generic.yml
index 2559371..2d54045 100644
--- a/skills/github-release/templates/release-generic.yml
+++ b/skills/github-release/templates/release-generic.yml
@@ -40,8 +40,17 @@ jobs:
         uses: sigstore/cosign-installer@v3
       - name: Sign artifacts
         run: |
+          # Use .sigstore.json extension (NOT cosign's default .bundle).
+          # OSSF Scorecard's Signed-Releases check pattern-matches against a
+          # fixed allowlist of signature extensions (.sig, .asc, .minisig,
+          # .sigstore, .sigstore.json, .intoto.jsonl). The .bundle extension
+          # cosign writes by default is NOT on that list, so cosign-signed
+          # releases score 0/10. The bytes inside the bundle file ARE the
+          # Sigstore bundle JSON format — the rename is purely cosmetic for
+          # tooling detection. `cosign verify-blob --bundle file.sigstore.json`
+          # works identically.
           for f in dist/*; do
-            cosign sign-blob "$f" --bundle "${f}.bundle" --yes
+            cosign sign-blob "$f" --bundle "${f}.sigstore.json" --yes
           done
       - name: Generate attestation
         uses: actions/attest-build-provenance@v2