Function executeFetch

packages/lang-core/src/runtime/queryManager.ts:208–307

(cacheKey: string, statementId: string)

  // ── Fetch execution ──────────────────────────────────────────────────────

  async function executeFetch(cacheKey: string, statementId: string) {
    if (!toolProvider) return;

    const q = queries.get(statementId);
    if (!q) return;

    // Capture the cache key at fetch start — if the query's key changes
    // while we're in-flight (deps changed), this fetch is stale.
    const fetchKey = cacheKey;
    const toolName = q.toolName;
    const args = q.args;

    // Mark in-flight — use undefined as "no data yet" sentinel (distinct from null)
    let entry = cache.get(fetchKey);
    if (!entry) {
      entry = { data: undefined, inFlight: true };
      cache.set(fetchKey, entry);
    } else {
      entry.inFlight = true;
    }
    q.loading = true;
    rebuildSnapshot();
    notify();

    try {
      const data = await toolProvider.callTool(toolName, (args as Record<string, unknown>) ?? {});
      if (disposed) return;
      // Query removed or moved to a different cache key while in-flight — discard
      const current = queries.get(statementId);
      if (!current || current.cacheKey !== fetchKey) {
        entry.inFlight = false;
        return;
      }

      entry.data = data ?? null;
      current.everFetched = true;
      current.error = undefined;

      // Clean up previous cache entry — clear prevCacheKey FIRST so
      // cleanupCacheEntry doesn't see this query as a live reference.
      if (current.prevCacheKey && current.prevCacheKey !== fetchKey) {
        const prevKey = current.prevCacheKey;
        current.prevCacheKey = undefined;
        cleanupCacheEntry(prevKey);
      }
    } catch (err) {
      // Only update error state if this fetch is still current
      const current = queries.get(statementId);
      if (current && current.cacheKey === fetchKey) {
        if (err instanceof ToolNotFoundError) {
          current.error = {
            source: "query",
            code: "tool-not-found",
            message: `Query tool "${toolName}" not found`,
            statementId,
            component: "Query",
            toolName,
            hint: err.availableTools.length