feat(mcp): report index publish metadata

Expose index_repository publish_kind and graph_changed in the JSON result so MCP clients can tell whether a run used a full, no-op, exact incremental, or containment route without relying on stderr logs.

Add a reusable pipeline publish-kind string helper plus focused pipeline and incremental response-contract tests. This is additive response metadata only; it does not change indexing behavior or enable incremental by default.

Signed-off-by: Andrew Hundt <ATHundt@gmail.com>

src/mcp/mcp.c

@@ -4995,6 +4995,9 @@ static char *handle_index_repository(cbm_mcp_server_t *srv, const char *args) {
 
     yyjson_mut_obj_add_str(doc, root, "project", project_name);
     yyjson_mut_obj_add_str(doc, root, "status", rc == 0 ? "indexed" : "error");
+    yyjson_mut_obj_add_str(doc, root, "publish_kind",
+                           cbm_pipeline_publish_kind_name(publish_kind));
+    yyjson_mut_obj_add_bool(doc, root, "graph_changed", graph_changed);
 
     if (rc == 0) {
         cbm_store_t *store = resolve_store(srv, project_name);

src/pipeline/pipeline.c

@@ -403,6 +403,23 @@ cbm_pipeline_publish_kind_t cbm_pipeline_publish_kind(const cbm_pipeline_t *p) {
     return p ? p->publish_kind : CBM_PIPELINE_PUBLISH_NONE;
 }
 
+const char *cbm_pipeline_publish_kind_name(cbm_pipeline_publish_kind_t kind) {
+    switch (kind) {
+    case CBM_PIPELINE_PUBLISH_NONE:
+        return "none";
+    case CBM_PIPELINE_PUBLISH_FULL:
+        return "full";
+    case CBM_PIPELINE_PUBLISH_INCREMENTAL_NOOP:
+        return "incremental_noop";
+    case CBM_PIPELINE_PUBLISH_INCREMENTAL_EXACT:
+        return "incremental_exact";
+    case CBM_PIPELINE_PUBLISH_INCREMENTAL_CONTAINMENT:
+        return "incremental_containment";
+    default:
+        return "unknown";
+    }
+}
+
 void cbm_pipeline_set_graph_changed(cbm_pipeline_t *p, bool changed) {
     if (p) {
         p->graph_changed = changed;

src/pipeline/pipeline.h

@@ -141,6 +141,7 @@ bool cbm_pipeline_graph_changed(const cbm_pipeline_t *p);
 /* Last publish route for the most recent run. This is observability for callers
  * that need derived-view policy decisions; it does not change graph contents. */
 cbm_pipeline_publish_kind_t cbm_pipeline_publish_kind(const cbm_pipeline_t *p);
+const char *cbm_pipeline_publish_kind_name(cbm_pipeline_publish_kind_t kind);
 
 /* ── Index lock (prevents concurrent pipeline runs on same DB) ──── */
 

tests/test_incremental.c

@@ -2174,6 +2174,21 @@ TEST(tool_index_mode_fast) {
     PASS();
 }
 
+TEST(tool_index_publish_metadata) {
+    double ms;
+    char *r = call_tool_timed("index_repository", &ms, "{\"repo_path\":\"%s\",\"mode\":\"fast\"}",
+                              g_repodir);
+    ASSERT(r != NULL);
+    ASSERT(strstr(r, "\\\"publish_kind\\\":\\\"") != NULL);
+    ASSERT(strstr(r, "\\\"graph_changed\\\":") != NULL);
+    ASSERT(strstr(r, "\\\"publish_kind\\\":\\\"full\\\"") != NULL ||
+           strstr(r, "\\\"publish_kind\\\":\\\"incremental_noop\\\"") != NULL ||
+           strstr(r, "\\\"publish_kind\\\":\\\"incremental_exact\\\"") != NULL ||
+           strstr(r, "\\\"publish_kind\\\":\\\"incremental_containment\\\"") != NULL);
+    free(r);
+    PASS();
+}
+
 TEST(tool_index_invalid_path) {
     double ms;
     char *r = call_tool_timed("index_repository", &ms, "{\"repo_path\":\"/nonexistent/path/xyz\"}");
@@ -3264,6 +3279,7 @@ SUITE(incremental) {
 
     /* Phase 19: index_repository params */
     RUN_TEST(tool_index_mode_fast);
+    RUN_TEST(tool_index_publish_metadata);
     RUN_TEST(tool_index_invalid_path);
     RUN_TEST(tool_index_missing_param);
 

tests/test_pipeline.c

@@ -10013,6 +10013,19 @@ TEST(pipeline_unit_threshold_setters_clamp_invalid_values) {
     PASS();
 }
 
+TEST(pipeline_publish_kind_names_are_stable) {
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name(CBM_PIPELINE_PUBLISH_NONE), "none");
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name(CBM_PIPELINE_PUBLISH_FULL), "full");
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name(CBM_PIPELINE_PUBLISH_INCREMENTAL_NOOP),
+                  "incremental_noop");
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name(CBM_PIPELINE_PUBLISH_INCREMENTAL_EXACT),
+                  "incremental_exact");
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name(CBM_PIPELINE_PUBLISH_INCREMENTAL_CONTAINMENT),
+                  "incremental_containment");
+    ASSERT_STR_EQ(cbm_pipeline_publish_kind_name((cbm_pipeline_publish_kind_t)999), "unknown");
+    PASS();
+}
+
 TEST(pipeline_apply_config_sets_all_thresholds) {
     char tmpdir[256];
     snprintf(tmpdir, sizeof(tmpdir), "/tmp/cbm_pipeline_cfg_XXXXXX");
@@ -11175,6 +11188,7 @@ SUITE(pipeline) {
     /* Resource management & internal helper tests */
     RUN_TEST(pipeline_empty_path);
     RUN_TEST(pipeline_project_name_content);
+    RUN_TEST(pipeline_publish_kind_names_are_stable);
     RUN_TEST(pipeline_cancel_sets_flag);
     RUN_TEST(pipeline_double_cancel);
     RUN_TEST(pipeline_double_free_prevention);