chore: import upstream snapshot with attribution

tests/repro/repro_issue480.c

@@ -0,0 +1,173 @@
+/*
+ * repro_issue480.c — Reproduce-first case for OPEN bug #480.
+ *
+ * Issue: #480 — "trace_path returns empty for all functions despite
+ *               traversable CALLS edges (v0.8.1, macOS arm64)"
+ *
+ * Root cause (identified by maintainer DeusData + reporter halindrome):
+ *   handle_trace_call_path() calls cbm_store_find_nodes_by_name() to locate
+ *   the start node for BFS.  On the affected build, the name-to-node lookup
+ *   returns node_count == 0 for EVERY function name — even names that the
+ *   graph clearly contains (confirmed by query_graph Cypher returning the same
+ *   function with 5–8 inbound CALLS edges).  The fallback to
+ *   cbm_store_find_node_by_qn() also returns nothing, so the handler exits
+ *   with a "function not found" error OR (when the node IS found by name)
+ *   the BFS start-node id does not match any edge endpoint stored in the
+ *   graph, so cbm_store_bfs() returns visited_count == 0 and the "callers"
+ *   / "callees" JSON arrays are serialised empty.
+ *
+ *   The split: query_graph Cypher (direct SQL) traverses the same edges
+ *   correctly, while trace_path (BFS via start-node id) yields nothing.
+ *   This isolates the bug to trace_path's own start-node lookup or to how
+ *   the resolved node id is passed to cbm_store_bfs(), NOT to edge creation.
+ *
+ * Expected (correct) behaviour:
+ *   After indexing a two-function Python file where caller() calls callee(),
+ *   trace_path for "callee" with direction="inbound" must return a non-empty
+ *   "callers" array that contains a node named "caller".
+ *
+ * Actual (buggy) behaviour:
+ *   trace_path returns {"function":"callee","direction":"inbound","callers":[]}
+ *   — an empty "callers" array — even though CALLS edges exist in the graph
+ *   and are walkable via query_graph.
+ *
+ * Why RED on current code:
+ *   The precondition assertion (CALLS edges > 0) passes because edge creation
+ *   is correct.  The subsequent assertion that resp contains the string
+ *   "\"caller\"" (the caller function's name embedded in the callers array)
+ *   FAILS because cbm_store_bfs() finds no hops from the resolved start node.
+ *
+ * How this isolates the traversal bug from an extraction bug:
+ *   If CALLS edges were the problem, rh_count_edges(store, …, "CALLS") would
+ *   return 0 and the ASSERT_GT precondition would fire RED — visibly flagging
+ *   an extraction failure instead.  By asserting the precondition GREEN and
+ *   the trace_path result RED, we prove the edges exist and the fault lies
+ *   exclusively in trace_path's traversal layer.
+ *
+ * Fix location (not implemented here):
+ *   cbm_store_find_nodes_by_name() or cbm_store_bfs() in
+ *   src/store/store.c — the node id returned by name lookup must match
+ *   the source/target ids stored in the edges table.
+ */
+
+#include <foundation/compat.h>
+#include "test_framework.h"
+#include "repro_harness.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+/* ── Fixture ────────────────────────────────────────────────────────────────
+ *
+ * Two Python functions in one file:
+ *
+ *   def callee():
+ *       return 42
+ *
+ *   def caller():
+ *       return callee()
+ *
+ * Python has proven reliable CALLS extraction (test_extraction.c:python_calls
+ * asserts calls.count > 0 for a simpler fixture; the integration suite's
+ * main.py fixture yields CALLS edges that are visible via query_graph).
+ * caller() → callee() is a simple, unambiguous intra-file call: the extractor
+ * sees exactly one callee() call expression inside caller(), so the graph
+ * must have ≥ 1 CALLS edge after indexing.
+ */
+static const RFile k_files[] = {
+    {
+        "main.py",
+        "def callee():\n"
+        "    return 42\n"
+        "\n"
+        "def caller():\n"
+        "    return callee()\n"
+    }
+};
+
+/* ─────────────────────────────────────────────────────────────────────────
+ * repro_issue480_trace_path_nonempty_with_calls
+ *
+ * Precondition (must be GREEN to prove this is a traversal bug):
+ *   rh_count_edges(store, project, "CALLS") > 0
+ *
+ * The failing assertion (RED on buggy code):
+ *   The "callers" array in the trace_path response is non-empty and contains
+ *   the string "caller" (the name of the caller function).
+ * ───────────────────────────────────────────────────────────────────────── */
+TEST(repro_issue480_trace_path_nonempty_with_calls) {
+    RProj lp;
+    cbm_store_t *store = rh_index_files(&lp, k_files,
+                                        (int)(sizeof(k_files) / sizeof(k_files[0])));
+    ASSERT_NOT_NULL(store);
+
+    /* ── Precondition: extraction must have produced ≥ 1 CALLS edge ──────
+     * If this fires RED, the fixture or language has an extraction bug —
+     * that is a different problem from #480.  Switch to a different
+     * language fixture (e.g. Go utils.go with Multiply→Add) in that case. */
+    int calls_count = rh_count_edges(store, lp.project, "CALLS");
+    ASSERT_GT(calls_count, 0);
+
+    /* ── Invoke trace_path for "callee" with direction="inbound" ─────────
+     *
+     * Args match the trace_path schema (required: function_name, project):
+     *   function_name  — bare name "callee"; also tested by the reporter with
+     *                    the fully-qualified name, both yield empty on buggy code
+     *   project        — lp.project (derived from tmpdir by cbm_project_name_from_path)
+     *   direction      — "inbound": ask for callers of callee()
+     *   depth          — 2: enough to reach one hop (caller → callee)
+     *
+     * Expected response shape (correct):
+     *   {"function":"callee","direction":"inbound","callers":[{"name":"caller",...},...]}
+     *
+     * Buggy response shape:
+     *   {"function":"callee","direction":"inbound","callers":[]}
+     *   (or: {"error":"function not found",...} if the name lookup fails entirely)
+     */
+    char args[512];
+    snprintf(args, sizeof(args),
+             "{\"function_name\":\"callee\","
+             "\"project\":\"%s\","
+             "\"direction\":\"inbound\","
+             "\"depth\":2}",
+             lp.project);
+
+    char *resp = cbm_mcp_handle_tool(lp.srv, "trace_path", args);
+    ASSERT_NOT_NULL(resp);
+
+    /* The response must NOT be a "function not found" error.
+     * If the name lookup itself fails, this fires first and pinpoints the
+     * start-node lookup as the breakage site. */
+    ASSERT_NULL(strstr(resp, "function not found"));
+
+    /* The response is the MCP tool-result envelope
+     *   {"content":[{"type":"text","text":"<inner trace_path json>"}]}
+     * so the inner json is embedded as a STRING value and its quotes are
+     * backslash-escaped: the "callers" key appears as \"callers\" in the
+     * serialized response. Match the escaped form — the project's own
+     * passing trace_path tests (test_incremental.c, via resp_has_key) do the
+     * same. (The earlier unescaped strstr could never match a correctly
+     * escaped MCP envelope, which is why this repro was mis-targeted.)
+     *
+     * The "callers" key must appear (always emitted for inbound). */
+    ASSERT_NOT_NULL(strstr(resp, "\\\"callers\\\""));
+
+    /* The "callers" array must be NON-EMPTY. WHY RED on the #480 bug:
+     * cbm_store_bfs() returning 0 hops serialises \"callers\":[] (no caller
+     * QN in the response), so BOTH the empty-array guard and the caller-QN
+     * assertion fire RED. We assert the caller's qualified-name tail
+     * "main.caller" (unambiguous vs the callee "main.callee", and immune to
+     * escaping) so a populated, correctly-named caller hop is required. */
+    ASSERT_NULL(strstr(resp, "\\\"callers\\\":[]")); /* empty array = traversal bug */
+    ASSERT_NOT_NULL(strstr(resp, "main.caller"));    /* caller QN in results       */
+
+    free(resp);
+    rh_cleanup(&lp, store);
+    PASS();
+}
+
+/* ── Suite ─────────────────────────────────────────────────────────────── */
+SUITE(repro_issue480) {
+    RUN_TEST(repro_issue480_trace_path_nonempty_with_calls);
+}