fix(git): harden Gitea PR metadata lookup

docs/scratchpads/mvp-20260312.md

@@ -653,3 +653,9 @@ Independent security review surfaced three high-impact and four medium findings;
 2. After merge, kickoff M3-01 (DTOs) on `feat/federation-m3-types` with sonnet subagent in worktree
 3. Once M3-01 lands, fan out: M3-02 (harness) || M3-03 (AuthGuard) → M3-04 (ScopeService) || M3-08 (FederationClient)
 4. Re-converge at M3-10 (Integration) → M3-11 (E2E)
+
+### Session 24 — 2026-05-22 — Gitea PR metadata wrapper hardening
+
+- Fixed `packages/mosaic/framework/tools/git/pr-metadata.sh` Gitea path to fail closed on non-2xx API responses instead of normalizing API error JSON into null/empty PR metadata.
+- Added token fallback behavior: try explicit `GITEA_TOKEN`, Mosaic credential-loader token, then matching `~/.git-credentials` HTTPS token; this handles stale host-scoped credential-loader entries while preserving existing credential sources.
+- Confirmed real U-Connect Gitea PRs #1905 and #1908 now return `number`, `headRefName`, `baseRefName`, `state`, `author`, `url`, and `mergeable` correctly, restoring `pr-merge.sh` base branch detection.

packages/mosaic/framework/tools/git/pr-metadata.sh

@@ -69,32 +69,81 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
 
     API_URL="https://${HOST}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}"
 
-    GITEA_API_TOKEN=$(get_gitea_token "$HOST" || true)
+    declare -a TOKEN_CANDIDATES=()
+    add_token_candidate() {
+        local candidate="$1"
+        [[ -z "$candidate" ]] && return 0
+        local existing
+        for existing in "${TOKEN_CANDIDATES[@]:-}"; do
+            [[ "$existing" == "$candidate" ]] && return 0
+        done
+        TOKEN_CANDIDATES+=("$candidate")
+    }
 
-    if [[ -n "$GITEA_API_TOKEN" ]]; then
+    add_token_candidate "${GITEA_TOKEN:-}"
-        RAW=$(curl -sS -H "Authorization: token $GITEA_API_TOKEN" "$API_URL")
+    add_token_candidate "$(get_gitea_token "$HOST" || true)"
-    else
+
-        RAW=$(curl -sS "$API_URL")
+    # Git HTTPS credentials often contain a valid Gitea API token even when a
+    # Mosaic credential-source entry is stale. Try them as a fallback before
+    # falling back to an unauthenticated request.
+    CREDS_FILE="$HOME/.git-credentials"
+    if [[ -f "$CREDS_FILE" ]]; then
+        while IFS= read -r credential_token; do
+            add_token_candidate "$credential_token"
+        done < <(grep -F "$HOST" "$CREDS_FILE" 2>/dev/null | sed -n 's#https\?://[^@]*:\([^@/]*\)@.*#\1#p')
+    fi
+
+    RAW=""
+    HTTP_STATUS=""
+    if [[ ${#TOKEN_CANDIDATES[@]} -gt 0 ]]; then
+        for GITEA_API_TOKEN in "${TOKEN_CANDIDATES[@]}"; do
+            RESPONSE_FILE=$(mktemp)
+            HTTP_STATUS=$(curl -sS -o "$RESPONSE_FILE" -w '%{http_code}' -H "Authorization: token $GITEA_API_TOKEN" "$API_URL" || true)
+            RAW=$(cat "$RESPONSE_FILE")
+            rm -f "$RESPONSE_FILE"
+            [[ "$HTTP_STATUS" =~ ^2 ]] && break
+        done
+    fi
+
+    if [[ ! "$HTTP_STATUS" =~ ^2 ]]; then
+        RESPONSE_FILE=$(mktemp)
+        HTTP_STATUS=$(curl -sS -o "$RESPONSE_FILE" -w '%{http_code}' "$API_URL" || true)
+        RAW=$(cat "$RESPONSE_FILE")
+        rm -f "$RESPONSE_FILE"
+    fi
+
+    if [[ ! "$HTTP_STATUS" =~ ^2 ]]; then
+        ERROR_MESSAGE=$(printf '%s' "$RAW" | python3 -c 'import json, sys
+try:
+    data=json.load(sys.stdin)
+except Exception:
+    data={}
+print(data.get("message") or data.get("error") or "unknown error")')
+        echo "Error: failed to fetch Gitea PR #$PR_NUMBER from $HOST/$OWNER/$REPO (HTTP $HTTP_STATUS): $ERROR_MESSAGE" >&2
+        exit 1
     fi
 
     # Normalize Gitea response to match our expected schema
     METADATA=$(echo "$RAW" | python3 -c "
 import json, sys
 data = json.load(sys.stdin)
+head = data.get('head') or {}
+base = data.get('base') or {}
+user = data.get('user') or {}
 normalized = {
-    'number': data.get('number'),
+    'number': data.get('number') or data.get('index'),
     'title': data.get('title'),
     'body': data.get('body', ''),
     'state': data.get('state'),
-    'author': data.get('user', {}).get('login', ''),
+    'author': user.get('login', ''),
-    'headRefName': data.get('head', {}).get('ref', ''),
+    'headRefName': head.get('ref') or head.get('label', '').split(':')[-1],
-    'baseRefName': data.get('base', {}).get('ref', ''),
+    'baseRefName': base.get('ref') or base.get('label', '').split(':')[-1],
     'labels': [l.get('name', '') for l in data.get('labels', [])],
     'assignees': [a.get('login', '') for a in data.get('assignees', [])],
     'milestone': data.get('milestone', {}).get('title', '') if data.get('milestone') else '',
     'createdAt': data.get('created_at', ''),
     'updatedAt': data.get('updated_at', ''),
-    'url': data.get('html_url', ''),
+    'url': data.get('html_url') or data.get('url', ''),
     'isDraft': data.get('draft', False),
     'mergeable': data.get('mergeable'),
     'diffUrl': data.get('diff_url', ''),