feat(backend): ThtRunner wrapper for tht --json (sessions, sql preview/export)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/tht/tht-runner.ts

@@ -0,0 +1,86 @@
+import { spawn } from "node:child_process";
+
+export interface ThtConfig {
+  thtBin: string;
+  harnessDir: string;
+  configPath: string;
+}
+
+export interface SessionRow {
+  id: string;
+  status: string;
+  question: string;
+  summary: string | null;
+  created_at: string;
+  updated_at: string | null;
+  author: string | null;
+}
+
+export class ThtRunner {
+  constructor(private cfg: ThtConfig) {}
+
+  run(args: string[]): Promise<{ code: number; stdout: string; stderr: string }> {
+    return new Promise((resolve) => {
+      const ch = spawn(this.cfg.thtBin, ["-c", this.cfg.configPath, ...args], {
+        cwd: this.cfg.harnessDir,
+      });
+      let stdout = "";
+      let stderr = "";
+      ch.stdout.on("data", (d: Buffer) => (stdout += d));
+      ch.stderr.on("data", (d: Buffer) => (stderr += d));
+      ch.on("close", (code) => resolve({ code: code ?? 0, stdout, stderr }));
+    });
+  }
+
+  private async json<T>(args: string[]): Promise<T> {
+    const { code, stdout, stderr } = await this.run(args);
+    if (code !== 0) throw new Error(`tht ${args.join(" ")} exit ${code}: ${stderr.trim()}`);
+    return JSON.parse(stdout) as T;
+  }
+
+  async sessionNew(o: {
+    question: string;
+    provider?: string;
+    model?: string;
+    thinking?: string;
+    name?: string;
+  }) {
+    const a = ["session", "new", o.question];
+    for (const [f, v] of [
+      ["--provider", o.provider],
+      ["--model", o.model],
+      ["--thinking", o.thinking],
+      ["--name", o.name],
+    ] as const) {
+      if (v) a.push(f, v);
+    }
+    a.push("--json");
+    return this.json<{ id: string }>(a);
+  }
+
+  sessionList() {
+    return this.json<SessionRow[]>(["session", "list", "--json"]);
+  }
+
+  sessionShow(id: string) {
+    return this.json<unknown>(["session", "show", id, "--json"]);
+  }
+
+  sqlPreview(id: string, p: { limit?: number; offset?: number }) {
+    const a = ["sql", "preview", `sessions/${id}/sql_final.sql`, "--session", id, "--json"];
+    if (p.limit != null) a.push("--limit", String(p.limit));
+    if (p.offset != null) a.push("--offset", String(p.offset));
+    return this.json<{
+      columns: string[];
+      rows: unknown[][];
+      execution_ms: number;
+      truncated: boolean;
+    }>(a);
+  }
+
+  async sqlExport(id: string) {
+    const { code, stdout, stderr } = await this.run(["sql", "export", "--session", id]);
+    if (code !== 0) throw new Error(`tht sql export exit ${code}: ${stderr.trim()}`);
+    return { path: stdout.trim() };
+  }
+}

backend/test/tht-runner.test.ts

@@ -0,0 +1,14 @@
+import { test, expect } from "vitest";
+import { ThtRunner } from "../src/tht/tht-runner.js";
+
+test("sessionNew parses id from JSON", async () => {
+  const r = new ThtRunner({ thtBin: "tht", harnessDir: "/h", configPath: "config/tht.yaml" });
+  r.run = async () => ({ code: 0, stdout: '{"id":"2026-06-27-100000-x"}', stderr: "" });
+  expect(await r.sessionNew({ question: "q" })).toEqual({ id: "2026-06-27-100000-x" });
+});
+
+test("run with exit != 0 propagates error with stderr", async () => {
+  const r = new ThtRunner({ thtBin: "tht", harnessDir: "/h", configPath: "config/tht.yaml" });
+  r.run = async () => ({ code: 1, stdout: "", stderr: "ERRORE: boom" });
+  await expect(r.sessionList()).rejects.toThrow(/boom/);
+});