feat(git-tools): consume .mosaic/repo.json declarations in compat mode (T51 WP5b) (#1416)

Co-authored-by: code-be-02 <[email protected]>

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

@@ -78,8 +78,8 @@ gitea_pr_create_api() {
     # historical "main" literal, which mistargeted every fallback PR on
     # repos whose trunk is not main (e.g. mosaicstack/stack -> next).
     local api_base=""
-    if [[ -n "$BASE_BRANCH" ]]; then
-        api_base="$BASE_BRANCH"
+    if [[ -n "$EFFECTIVE_BASE" ]]; then
+        api_base="$EFFECTIVE_BASE"
     else
         api_base=$(gitea_default_branch) || {
             echo "Error: could not resolve the forge default branch for the API-fallback base; pass -B <branch> explicitly" >&2
@@ -198,6 +198,52 @@ if [[ -z "$HEAD_BRANCH" ]]; then
     HEAD_BRANCH=$(git branch --show-current)
 fi
 
+# T51 WP5b: declaration-driven base resolution (spec 4.1). Precedence:
+#   explicit -B  -> validated as an ALLOWED transition (4.2: a flag is input,
+#                    not authority) when a consumable declaration exists
+#   declared trunk (v2 declarations only) -> used directly
+#   legacy        -> WP5a forge-default floor (unmanaged/absent/v1, 4.3)
+# shellcheck source=packages/mosaic/framework/tools/git/repo-decl.sh
+if [ -f "$SCRIPT_DIR/repo-decl.sh" ]; then
+    source "$SCRIPT_DIR/repo-decl.sh"
+    repo_decl_load
+else
+    DECL_STATE=absent; DECL_SCHEMA=""
+    repo_decl_warn() { printf 'repo-decl: %s\n' "$*" >&2; }
+    repo_decl_report_invalid() { :; }
+    repo_decl_warn_absent_reversible() { :; }
+    repo_decl_warn_absent_irreversible() { :; }
+    repo_decl_remote_matches() { return 0; }
+    repo_decl_check_transition() { return 2; }
+fi
+EFFECTIVE_BASE="$BASE_BRANCH"
+case "$DECL_STATE" in
+    invalid) repo_decl_report_invalid ;;
+esac
+if [[ "$DECL_STATE" == valid && "$DECL_SCHEMA" != 2 ]]; then
+    repo_decl_warn "declaration is v$DECL_SCHEMA — carries no consumable flow/trunk fields; legacy behavior"
+fi
+if [[ "$DECL_STATE" == valid && "$DECL_SCHEMA" == 2 ]]; then
+    # Write path: a normalized-remote mismatch refuses (spec 5.3).
+    if ! repo_decl_remote_matches; then
+        echo "Error: origin remote does not match the declared canonical_remote (spec 5.3, write path) — refusing to create a PR against the wrong forge. Fix the origin remote or the declaration." >&2
+        exit 1
+    fi
+    if [[ -n "$BASE_BRANCH" ]]; then
+        trc=0
+        repo_decl_check_transition "$HEAD_BRANCH" "$BASE_BRANCH" || trc=$?
+        if [[ "$trc" == 1 ]]; then
+            echo "Error: -B '$BASE_BRANCH' is not an allowed transition for head '$HEAD_BRANCH' under the declared flow (spec 4.2). The declaration governs; supply an allowed base." >&2
+            exit 1
+        fi
+        # trc 2 cannot happen here (state=valid): 0 = allowed
+    else
+        EFFECTIVE_BASE="$DECL_TRUNK"
+    fi
+elif [[ -z "$BASE_BRANCH" ]]; then
+    repo_decl_warn_absent_reversible "pr-create"
+fi
+
 # Add issue reference to body if provided
 if [[ -n "$ISSUE" ]]; then
     if [[ -n "$BODY" ]]; then
@@ -215,7 +261,7 @@ case "$PLATFORM" in
     github)
         CMD=(gh pr create --title "$TITLE")
         [[ -n "$BODY" ]] && CMD+=(--body "$BODY")
-        [[ -n "$BASE_BRANCH" ]] && CMD+=(--base "$BASE_BRANCH")
+        [[ -n "$EFFECTIVE_BASE" ]] && CMD+=(--base "$EFFECTIVE_BASE")
         [[ -n "$HEAD_BRANCH" ]] && CMD+=(--head "$HEAD_BRANCH")
         [[ -n "$LABELS" ]] && CMD+=(--label "$LABELS")
         [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
@@ -240,7 +286,7 @@ case "$PLATFORM" in
         REPO_ARGS=(--repo "$REPO_SLUG" --login "$GITEA_LOGIN_NAME")
         CMD=(tea pr create "${REPO_ARGS[@]}" --title "$TITLE")
         [[ -n "$BODY" ]] && CMD+=(--description "$BODY")
-        [[ -n "$BASE_BRANCH" ]] && CMD+=(--base "$BASE_BRANCH")
+        [[ -n "$EFFECTIVE_BASE" ]] && CMD+=(--base "$EFFECTIVE_BASE")
         [[ -n "$HEAD_BRANCH" ]] && CMD+=(--head "$HEAD_BRANCH")
 
         # Handle labels for tea