diff --git a/.gitea/workflows/secret-scan.yml b/.gitea/workflows/secret-scan.yml
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+name: Secret scan
+
+# Hard CI gate. Refuses any PR / push whose diff additions contain a
+# recognisable credential. Defense-in-depth for the #2090-class incident
+# (2026-04-24): GitHub's hosted Copilot Coding Agent leaked a ghs_*
+# installation token into tenant-proxy/package.json via `npm init`
+# slurping the URL from a token-embedded origin remote. We can't fix
+# upstream's clone hygiene, so we gate here.
+#
+# Same regex set as the runtime's bundled pre-commit hook
+# (molecule-ai-workspace-runtime: molecule_runtime/scripts/pre-commit-checks.sh).
+# Keep the two sides aligned when adding patterns.
+#
+# Ported from .github/workflows/secret-scan.yml so the gate actually
+# fires on Gitea Actions. Differences from the GitHub version:
+#   - drops `merge_group` event (Gitea has no merge queue)
+#   - drops `workflow_call` (no cross-repo reusable invocation on Gitea)
+#   - SELF path updated to .gitea/workflows/secret-scan.yml
+# The job name + step name are identical to the GitHub workflow so the
+# status-check context (`Secret scan / Scan diff for credential-shaped
+# strings (pull_request)`) matches branch protection on molecule-core/main.
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  push:
+    branches: [main, staging]
+
+jobs:
+  scan:
+    name: Scan diff for credential-shaped strings
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 2  # need previous commit to diff against on push events
+
+      # For pull_request events the diff base may be many commits behind
+      # HEAD and absent from the shallow clone. Fetch it explicitly.
+      - name: Fetch PR base SHA (pull_request events only)
+        if: github.event_name == 'pull_request'
+        run: git fetch --depth=1 origin ${{ github.event.pull_request.base.sha }}
+
+      - name: Refuse if credential-shaped strings appear in diff additions
+        env:
+          # Plumb event-specific SHAs through env so the script doesn't
+          # need conditional `${{ ... }}` interpolation per event type.
+          # github.event.before/after only exist on push events;
+          # pull_request has pull_request.base.sha / pull_request.head.sha.
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          PR_HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          PUSH_BEFORE: ${{ github.event.before }}
+          PUSH_AFTER: ${{ github.event.after }}
+        run: |
+          # Pattern set covers GitHub family (the actual #2090 vector),
+          # Anthropic / OpenAI / Slack / AWS. Anchored on prefixes with low
+          # false-positive rates against agent-generated content. Mirror of
+          # molecule-ai-workspace-runtime/molecule_runtime/scripts/pre-commit-checks.sh
+          # — keep aligned.
+          SECRET_PATTERNS=(
+            'ghp_[A-Za-z0-9]{36,}'           # GitHub PAT (classic)
+            'ghs_[A-Za-z0-9]{36,}'           # GitHub App installation token
+            'gho_[A-Za-z0-9]{36,}'           # GitHub OAuth user-to-server
+            'ghu_[A-Za-z0-9]{36,}'           # GitHub OAuth user
+            'ghr_[A-Za-z0-9]{36,}'           # GitHub OAuth refresh
+            'github_pat_[A-Za-z0-9_]{82,}'   # GitHub fine-grained PAT
+            'sk-ant-[A-Za-z0-9_-]{40,}'      # Anthropic API key
+            'sk-proj-[A-Za-z0-9_-]{40,}'     # OpenAI project key
+            'sk-svcacct-[A-Za-z0-9_-]{40,}'  # OpenAI service-account key
+            'sk-cp-[A-Za-z0-9_-]{60,}'       # MiniMax API key (F1088 vector — caught only after the fact)
+            'xox[baprs]-[A-Za-z0-9-]{20,}'   # Slack tokens
+            'AKIA[0-9A-Z]{16}'               # AWS access key ID
+            'ASIA[0-9A-Z]{16}'               # AWS STS temp access key ID
+          )
+
+          # Determine the diff base. Each event type stores its SHAs in
+          # a different place — see the env block above.
+          case "${{ github.event_name }}" in
+            pull_request)
+              BASE="$PR_BASE_SHA"
+              HEAD="$PR_HEAD_SHA"
+              ;;
+            *)
+              BASE="$PUSH_BEFORE"
+              HEAD="$PUSH_AFTER"
+              ;;
+          esac
+
+          # On push events with shallow clones, BASE may be present in
+          # the event payload but absent from the local object DB
+          # (fetch-depth=2 doesn't always reach the previous commit
+          # across true merges). Try fetching it on demand. If the
+          # fetch fails — e.g. the SHA was force-overwritten — we fall
+          # through to the empty-BASE branch below, which scans the
+          # entire tree as if every file were new. Correct, just slow.
+          if [ -n "$BASE" ] && ! echo "$BASE" | grep -qE '^0+$'; then
+            if ! git cat-file -e "$BASE" 2>/dev/null; then
+              git fetch --depth=1 origin "$BASE" 2>/dev/null || true
+            fi
+          fi
+
+          # Files added or modified in this change.
+          if [ -z "$BASE" ] || echo "$BASE" | grep -qE '^0+$' || ! git cat-file -e "$BASE" 2>/dev/null; then
+            # New branch / no previous SHA / BASE unreachable — check the
+            # entire tree as added content. Slower, but correct on first
+            # push.
+            CHANGED=$(git ls-tree -r --name-only HEAD)
+            DIFF_RANGE=""
+          else
+            CHANGED=$(git diff --name-only --diff-filter=AM "$BASE" "$HEAD")
+            DIFF_RANGE="$BASE $HEAD"
+          fi
+
+          if [ -z "$CHANGED" ]; then
+            echo "No changed files to inspect."
+            exit 0
+          fi
+
+          # Self-exclude: this workflow file legitimately contains the
+          # pattern strings as regex literals. Without an exclude it would
+          # block its own merge. Both the .github/ original and this
+          # .gitea/ port are excluded so a sync between them stays clean.
+          SELF_GITHUB=".github/workflows/secret-scan.yml"
+          SELF_GITEA=".gitea/workflows/secret-scan.yml"
+
+          OFFENDING=""
+          # `while IFS= read -r` (not `for f in $CHANGED`) so filenames
+          # containing whitespace don't word-split silently — a path
+          # with a space would otherwise produce two iterations on
+          # tokens that aren't real filenames, breaking the
+          # self-exclude + diff lookup.
+          while IFS= read -r f; do
+            [ -z "$f" ] && continue
+            [ "$f" = "$SELF_GITHUB" ] && continue
+            [ "$f" = "$SELF_GITEA" ] && continue
+            if [ -n "$DIFF_RANGE" ]; then
+              ADDED=$(git diff --no-color --unified=0 "$BASE" "$HEAD" -- "$f" 2>/dev/null | grep -E '^\+[^+]' || true)
+            else
+              # No diff range (new branch first push) — scan the full file
+              # contents as if every line were new.
+              ADDED=$(cat "$f" 2>/dev/null || true)
+            fi
+            [ -z "$ADDED" ] && continue
+            for pattern in "${SECRET_PATTERNS[@]}"; do
+              if echo "$ADDED" | grep -qE "$pattern"; then
+                OFFENDING="${OFFENDING}${f} (matched: ${pattern})\n"
+                break
+              fi
+            done
+          done <<< "$CHANGED"
+
+          if [ -n "$OFFENDING" ]; then
+            echo "::error::Credential-shaped strings detected in diff additions:"
+            # `printf '%b' "$OFFENDING"` interprets backslash escapes
+            # (the literal `\n` we appended above becomes a newline)
+            # WITHOUT treating OFFENDING as a format string. Plain
+            # `printf "$OFFENDING"` is a format-string sink: a filename
+            # containing `%` would be interpreted as a conversion
+            # specifier, corrupting the error message (or printing
+            # `%(missing)` artifacts).
+            printf '%b' "$OFFENDING"
+            echo ""
+            echo "The actual matched values are NOT echoed here, deliberately —"
+            echo "round-tripping a leaked credential into CI logs widens the blast"
+            echo "radius (logs are searchable + retained)."
+            echo ""
+            echo "Recovery:"
+            echo "  1. Remove the secret from the file. Replace with an env var"
+            echo "     reference (e.g. \${{ secrets.GITHUB_TOKEN }} in workflows,"
+            echo "     process.env.X in code)."
+            echo "  2. If the credential was already pushed (this PR's commit"
+            echo "     history reaches a public ref), treat it as compromised —"
+            echo "     ROTATE it immediately, do not just remove it. The token"
+            echo "     remains valid in git history forever and may be in any"
+            echo "     log/cache that consumed this branch."
+            echo "  3. Force-push the cleaned commit (or stack a revert) and"
+            echo "     re-run CI."
+            echo ""
+            echo "If the match is a false positive (test fixture, docs example,"
+            echo "or this workflow's own regex literals): use a clearly-fake"
+            echo "placeholder like ghs_EXAMPLE_DO_NOT_USE that doesn't satisfy"
+            echo "the length suffix, OR add the file path to the SELF exclude"
+            echo "list in this workflow with a short reason."
+            echo ""
+            echo "Mirror of the regex set lives in the runtime's bundled"
+            echo "pre-commit hook (molecule-ai-workspace-runtime:"
+            echo "molecule_runtime/scripts/pre-commit-checks.sh) — keep aligned."
+            exit 1
+          fi
+
+          echo "✓ No credential-shaped strings in this change."