fix(pipeline): track produced file paths accurately for deploy URL

- RunContext.producedFiles[] accumulates repo-relative paths of extracted
  code files as juniors write them
- implement selfTestReport now includes producedFiles[]
- runner extractStageText forwards producedFiles= in priorStages
- derivePreviewUrl uses producedFiles list first (exact match), then falls
  back to rawUrlBase/index.html heuristic
- Fixes bug where deployUrl pointed to files/index.html but actual repo
  path was implement/files/frontend/sprints/SPRINT-AUTO/index.html

sister-agent/src/spawn.ts

@@ -31,6 +31,8 @@ interface RunContext {
   rails: RailsClient;
   agentName: string;
   workspaceDir: string;
+  /** Aggregated code file paths (relative to pipeline repo root) across all juniors */
+  producedFiles: string[];
 }
 
 /**
@@ -49,7 +51,13 @@ export async function executeInvocation(
   const workspaceDir = join(WORKSPACE_ROOT, req.pipelineId, req.stage);
   await mkdir(workspaceDir, { recursive: true });
 
-  const ctx: RunContext = { req, rails, agentName, workspaceDir };
+  const ctx: RunContext = {
+    req,
+    rails,
+    agentName,
+    workspaceDir,
+    producedFiles: [],
+  };
 
   // 1) Manager itself runs first (it is the single root). Its output is the
   //    strategic decision that feeds into children.
@@ -137,7 +145,13 @@ export async function executeInvocation(
       .join("\n\n---\n\n")
       .slice(0, 6000);
 
-    return buildSuccessResult(req.stage, req.task, aggregated, gitResult);
+    return buildSuccessResult(
+      req.stage,
+      req.task,
+      aggregated,
+      gitResult,
+      ctx.producedFiles,
+    );
   } catch (err) {
     const errorReason = err instanceof Error ? err.message : String(err);
     await rails.recordEvent(managerId, "failed", { errorReason });
@@ -265,6 +279,12 @@ async function maybeExtractFiles(
   if (blocks.length === 0) return [];
 
   const saved = await saveExtractedFiles(ctx.workspaceDir, blocks);
+  // Track the repo-relative path (e.g., implement/files/frontend/index.html)
+  // so the deploy stage can build an accurate preview URL.
+  for (const f of saved) {
+    const repoRelPath = `${ctx.req.stage}/files/${f.path}`;
+    ctx.producedFiles.push(repoRelPath);
+  }
   return saved.map((f) => {
     const base: { path: string; lang: string; absPath?: string } = {
       path: f.path,
@@ -389,12 +409,19 @@ function derivePreviewUrl(
   const rawBase = rawBaseMatch?.[1];
   if (!rawBase) return "";
 
-  // Heuristic: if there's an index.html path referenced anywhere in the
-  // priorStages text, link directly to it. Otherwise link to the repo root.
-  const htmlMatch = impl.text.match(/([a-zA-Z0-9_\-./]+\.html)/);
-  if (htmlMatch?.[1]) {
-    return `${rawBase}/files/${htmlMatch[1]}`;
+  // Prefer the exact producedFiles list emitted by implement stage.
+  const producedMatch = impl.text.match(/producedFiles=([^\n]+)/);
+  if (producedMatch?.[1]) {
+    const files = producedMatch[1]
+      .split(",")
+      .map((s) => s.trim())
+      .filter(Boolean);
+    const html = files.find((f) => f.toLowerCase().endsWith(".html"));
+    if (html) return `${rawBase}/${html}`;
+    if (files[0]) return `${rawBase}/${files[0]}`;
   }
+
+  // Fallback: browse view
   return rawBase.replace("/raw/branch/main", "");
 }
 
@@ -409,6 +436,7 @@ function buildSuccessResult(
     commit: string;
     filesCount: number;
   } | null,
+  producedFiles: string[] = [],
 ): HandoffMessage {
   const summary = outputText?.slice(0, 2000) ?? "";
   switch (stage) {
@@ -433,6 +461,7 @@ function buildSuccessResult(
           workdir: task.workdir || "",
           selfTestReport: {
             summary,
+            producedFiles,
             ...(gitResult?.ok && {
               repoUrl: gitResult.repoUrl,
               rawUrlBase: gitResult.rawUrlBase,

src/orchestrator/runner.ts

@@ -204,6 +204,7 @@ function extractStageText(h: HandoffMessage): string {
             repoUrl?: string;
             rawUrlBase?: string;
             filesCount?: number;
+            producedFiles?: string[];
           }
         | undefined;
       const parts: string[] = [];
@@ -213,6 +214,9 @@ function extractStageText(h: HandoffMessage): string {
       if (typeof report?.filesCount === "number") {
         parts.push(`[git] filesCount=${report.filesCount}`);
       }
+      if (report?.producedFiles && report.producedFiles.length > 0) {
+        parts.push(`[git] producedFiles=${report.producedFiles.join(",")}`);
+      }
       return parts.join("\n");
     }
     case "review": {