fix(jobs): strip internal paths from all worker SSE error frames

Closes #71. Several error paths in the worker could leak internal
filesystem paths (/tmp/workspace, /data/ai/venv, /app) through SSE
frames, resultPayload objects, and Redis batch-error lists. The
existing stripInternalPaths call at worker.ts line 345 only covered
the single-file processToolJob catch block.

Wrapped 6 additional call sites:
- processPipelineStep: prevError from DB and catch errorMsg
- processPipelineFinalize: composed errorMsg reaching SSE,
  recordChildOutcome, and resultPayload
- processBatchChild: catch error reaching recordChildOutcome
  and resultPayload
- processBatchFinalize: manifest errorMsg from DB rows
- recordChildOutcome (batch-progress.ts): defense-in-depth
  strip before Redis rpush

Added 10 unit tests for stripInternalPaths covering /tmp, /data,
/app, /opt, /home, /workspace, multi-path messages, safe passthrough,
and pipeline-step wrapping.

apps/api/src/jobs/batch-progress.ts

@@ -12,6 +12,7 @@
  *                    "failed" only when every file failed
  */
 
+import { stripInternalPaths } from "../lib/errors.js";
 import { updateJobProgress } from "../routes/progress.js";
 import { sharedRedis } from "./connection.js";
 import { bullPrefix } from "./types.js";
@@ -37,7 +38,8 @@ export async function recordChildOutcome(
   const base = `${bullPrefix()}:batch:${parentId}`;
   const done = await r.incr(`${base}:${error ? "failed" : "done"}`);
   const other = Number((await r.get(`${base}:${error ? "done" : "failed"}`)) ?? 0);
-  if (error) await r.rpush(`${base}:errors`, JSON.stringify({ filename, error }));
+  if (error)
+    await r.rpush(`${base}:errors`, JSON.stringify({ filename, error: stripInternalPaths(error) }));
   await r.expire(`${base}:done`, 3600);
   await r.expire(`${base}:failed`, 3600);
   await r.expire(`${base}:errors`, 3600);

apps/api/src/jobs/worker.ts

@@ -387,10 +387,11 @@ async function processPipelineStep(job: Job<ToolJobData>): Promise<ToolJobResult
 
     if (!prevRow || prevRow.status === "failed" || !prevRow.outputRefs?.[0]) {
       // Previous step failed -- propagate the error without processing.
-      const prevError =
+      const prevError = stripInternalPaths(
         prevRow?.status === "failed"
           ? ((prevRow.error as { message?: string } | null)?.message ?? "Processing failed")
-          : "Previous step has no output";
+          : "Previous step has no output",
+      );
       await db
         .update(schema.jobs)
         .set({ status: "failed", completedAt: new Date(), error: { message: prevError } })
@@ -426,7 +427,7 @@ async function processPipelineStep(job: Job<ToolJobData>): Promise<ToolJobResult
     // Step failed -- return failure marker. processToolJob already
     // updated the DB row to "failed" and emitted a terminal event
     // on the step's own progress channel.
-    const errorMsg = err instanceof Error ? err.message : String(err);
+    const errorMsg = stripInternalPaths(err instanceof Error ? err.message : String(err));
     return {
       outputRefs: [],
       filename: data.filename,
@@ -494,7 +495,7 @@ async function processPipelineFinalize(job: Job<ToolJobData>): Promise<ToolJobRe
 
   // ── Failure path ────────────────────────────────────────────
   if (failedAtStep !== null) {
-    const errorMsg = `Step ${failedAtStep + 1}: ${failError}`;
+    const errorMsg = stripInternalPaths(`Step ${failedAtStep + 1}: ${failError}`);
 
     await db
       .update(schema.jobs)
@@ -596,7 +597,7 @@ async function processBatchChild(job: Job<ToolJobData>): Promise<ToolJobResult>
     await recordChildOutcome(job.data.parentId!, job.data.totalFiles!, job.data.filename);
     return result;
   } catch (err) {
-    const error = err instanceof Error ? err.message : String(err);
+    const error = stripInternalPaths(err instanceof Error ? err.message : String(err));
     await recordChildOutcome(job.data.parentId!, job.data.totalFiles!, job.data.filename, error);
     // Return a completed job with a failure marker so the parent runs.
     return {
@@ -647,7 +648,7 @@ async function processBatchFinalize(job: Job<ToolJobData>): Promise<ToolJobResul
     } else {
       const errorMsg = (row.error as { message?: string } | null)?.message ?? "Processing failed";
       const inputFilename = row.inputRefs?.[0]?.split("/").pop() ?? `file-${i}`;
-      manifest.push({ index: i, filename: inputFilename, error: errorMsg });
+      manifest.push({ index: i, filename: inputFilename, error: stripInternalPaths(errorMsg) });
     }
   }