1 files changed, 171 insertions, 0 deletions
diff --git a/src/features/markdown/adapter/text-file.ts b/src/features/markdown/adapter/text-file.ts
new file mode 100644
index 0000000..05ddb23
--- /dev/null
+++ b/src/features/markdown/adapter/text-file.ts
@@ -0,0 +1,171 @@
+import type {
+  TextFileContextResponse,
+  TextFileQuery,
+  TextFileResponse,
+} from "@dispatch/transport-contract";
+import type { TextFileClient, TextFileState } from "../types";
+
+const MAX_BYTES = 262144;
+const MAX_ENTRIES = 32;
+const MAX_PARALLEL = 4;
+interface Entry {
+  readonly listeners: Set<(state: TextFileState) => void>;
+  state: TextFileState;
+  controller: AbortController;
+}
+/** Per-mounted-chat, bounded cache: shared only by live references, never persisted. */
+export function createTextFileClient(
+  apiBase: string,
+  conversationId: string,
+  fetchImpl: typeof fetch,
+): TextFileClient {
+  const entries = new Map<string, Entry>();
+  let disposed = false;
+  let contextController = new AbortController();
+  let context: Promise<TextFileContextResponse> | null = null;
+  let active = 0;
+  const queue = new Map<string, () => void>();
+  const endpoint = `${apiBase.replace(/\/$/, "")}/conversations/${encodeURIComponent(conversationId)}`;
+  async function json(url: string, signal: AbortSignal): Promise<unknown> {
+    const response = await fetchImpl(url, { signal, cache: "no-store" });
+    const data: unknown = await response.json();
+    if (!response.ok) {
+      const error = data as { error?: string };
+      throw new Error(error.error ?? `Text file request failed (HTTP ${response.status})`);
+    }
+    return data;
+  }
+  function getContext(): Promise<TextFileContextResponse> {
+    context ??= json(`${endpoint}/text-file-context`, contextController.signal).then((data) => {
+      const c = data as TextFileContextResponse;
+      if (
+        c.conversationId !== conversationId ||
+        !(c.cwd === null || typeof c.cwd === "string") ||
+        !(c.computerId === null || typeof c.computerId === "string")
+      ) {
+        throw new Error("Invalid text file context response");
+      }
+      return c;
+    });
+    return context;
+  }
+  function publish(entry: Entry, state: TextFileState): void {
+    entry.state = state;
+    for (const listener of entry.listeners) listener(state);
+  }
+  async function load(path: string, entry: Entry, controller: AbortController): Promise<void> {
+    try {
+      if (controller.signal.aborted || disposed) return;
+      const c = await getContext();
+      if (controller.signal.aborted || disposed) return;
+      if (c.computerId !== null)
+        throw new Error(
+          "Text-file embeds are not available for remote computers. No local file was read.",
+        );
+      const query: TextFileQuery = {
+        path,
+        expectedCwd: c.cwd ?? "",
+        expectedComputerId: c.computerId ?? "",
+      };
+      const params = new URLSearchParams(query as unknown as Record<string, string>);
+      const data = (await json(
+        `${endpoint}/text-file?${params}`,
+        controller.signal,
+      )) as TextFileResponse;
+      if (
+        typeof data.text !== "string" ||
+        typeof data.path !== "string" ||
+        !data.path.startsWith("/") ||
+        !["markdown", "text"].includes(data.format) ||
+        data.maxBytes !== MAX_BYTES ||
+        !Number.isInteger(data.bytes) ||
+        data.bytes < 0 ||
+        data.bytes > MAX_BYTES ||
+        new TextEncoder().encode(data.text).length !== data.bytes
+      ) {
+        throw new Error("Invalid or oversized text file response (maximum 256 KiB)");
+      }
+      if (!controller.signal.aborted && !disposed) publish(entry, { kind: "ready", file: data });
+    } catch (error) {
+      if (!controller.signal.aborted && !disposed)
+        publish(entry, {
+          kind: "error",
+          message: error instanceof Error ? error.message : "Unable to read text file",
+        });
+    }
+  }
+  function drain(): void {
+    while (active < MAX_PARALLEL && queue.size) {
+      const next = queue.entries().next().value;
+      if (!next) return;
+      queue.delete(next[0]);
+      next[1]();
+    }
+  }
+  function start(path: string, entry: Entry): void {
+    entry.controller.abort();
+    const controller = new AbortController();
+    entry.controller = controller;
+    publish(entry, { kind: "loading" });
+    queue.set(path, () => {
+      if (controller.signal.aborted || disposed) return;
+      active++;
+      void load(path, entry, controller).finally(() => {
+        active--;
+        drain();
+      });
+    });
+    drain();
+  }
+  return {
+    subscribe(path, listener) {
+      if (disposed || (!entries.has(path) && entries.size >= MAX_ENTRIES)) {
+        listener({
+          kind: "error",
+          message: "Too many text-file embeds (maximum 32 active files).",
+        });
+        return () => {};
+      }
+      let entry = entries.get(path);
+      if (!entry) {
+        entry = {
+          listeners: new Set(),
+          state: { kind: "loading" },
+          controller: new AbortController(),
+        };
+        entries.set(path, entry);
+        start(path, entry);
+      }
+      entry.listeners.add(listener);
+      listener(entry.state);
+      const current = entry;
+      return () => {
+        current.listeners.delete(listener);
+        if (!current.listeners.size) {
+          current.controller.abort();
+          entries.delete(path);
+          queue.delete(path);
+        }
+        if (!entries.size) {
+          contextController.abort();
+          contextController = new AbortController();
+          context = null;
+        }
+      };
+    },
+    refresh(_path) {
+      // Refresh can reveal a context change: invalidate ALL live content before rereading.
+      contextController.abort();
+      contextController = new AbortController();
+      context = null;
+      for (const [path, entry] of entries) start(path, entry);
+    },
+    dispose() {
+      disposed = true;
+      contextController.abort();
+      for (const entry of entries.values()) entry.controller.abort();
+      entries.clear();
+      queue.clear();
+    },
+  };
+}