fix: resolve Gemini-identified pipeline data flow inconsistencies

Fix 3 issues found by Gemini full-chain analysis:

1. (High) cross_cutting_specs path format mismatch: feature-index.json
   uses relative paths ("role/file.md") but context-package uses full
   paths (".workflow/.../role/file.md"). Changed action-planning-agent
   to use endsWith() matching and read from context-package objects
   instead of raw feature-index strings.

2. (Medium) Add explicit feature_index_path field to context-package
   schema in context-search-agent, so task-generate-agent can read it
   directly instead of hardcoding paths. Updated both single-module
   and multi-module prompt templates with fallback logic.

3. (Medium) Expand synthesis_output in context-search-agent to include
   feature_driven sub-object pointing to feature-index.json and
   feature-specs/ directory alongside legacy synthesis-specification.md.

.claude/agents/action-planning-agent.md

@@ -157,9 +157,9 @@ mcp__exa__get_code_context_exa(
   - **Load on-demand**: Only load specs referenced by current task's feature mapping
   - **Note**: For structured metadata (`feature_id`, `slug`, `priority`), use `feature_index.features[]` instead
 - `brainstorm_artifacts.cross_cutting_specs[]`: Cross-cutting concern specifications (from context-package)
-  - Each spec: `cross_cutting_specs[i]` has `path` and `content`
+  - Each spec: `cross_cutting_specs[i]` has `path` (full project-relative) and `content`
   - **Load on-demand**: Only load when task touches shared/cross-cutting concerns
-  - **Note**: In feature-index.json, `cross_cutting_specs[]` is a plain string array (relative paths)
+  - **Path format note**: context-package uses full paths (`.workflow/.../role/file.md`), feature-index.json uses relative paths (`role/file.md`). Match using `endsWith()`.
 - `brainstorm_artifacts.role_analyses[]`: Role-specific analyses (legacy fallback, if array not empty)
   - Each role: `role_analyses[i].files[j]` has `path` and `content`
   - **Only used when**: `feature_index` does not exist (backward compatibility)
@@ -197,11 +197,17 @@ if (contextPackage.brainstorm_artifacts?.feature_index?.exists) {
     });
 
   // Step 3: Load cross-cutting specs only when needed
-  // Note: cross_cutting_specs in feature-index.json is a string array (relative paths)
+  // Note: feature-index.json uses relative paths ("role/file.md"),
+  //       context-package uses full paths (".workflow/.../role/file.md")
+  const crossCuttingFromPackage = contextPackage.brainstorm_artifacts.cross_cutting_specs || [];
   featureIndex.cross_cutting_specs
-    .filter(cs => task.context.artifacts.some(a => a.type === 'cross_cutting_spec' && a.path === cs))
+    .filter(cs => task.context.artifacts.some(a => a.type === 'cross_cutting_spec'))
     .forEach(cs => {
-      const crossCuttingContent = Read(cs);
+      // Match by path suffix since feature-index uses relative paths
+      const matched = crossCuttingFromPackage.find(pkg => pkg.path.endsWith(cs));
+      if (matched) {
+        const crossCuttingContent = matched.content || Read(matched.path);
+      }
     });
 
 } else if (contextPackage.brainstorm_artifacts?.role_analyses?.length > 0) {

.claude/agents/context-search-agent.md

@@ -338,7 +338,12 @@ if (dir_exists(brainstormDir)) {
     synthesis_output: {
       path: `${brainstormDir}/synthesis-specification.md`,
       exists: file_exists(`${brainstormDir}/synthesis-specification.md`),
-      content: Read(`${brainstormDir}/synthesis-specification.md`) || null
+      content: Read(`${brainstormDir}/synthesis-specification.md`) || null,
+      // New feature-driven artifacts (preferred over legacy synthesis-specification.md)
+      feature_driven: dir_exists(`${brainstormDir}/feature-specs`) ? {
+        feature_index: `${brainstormDir}/feature-specs/feature-index.json`,
+        feature_specs_dir: `${brainstormDir}/feature-specs/`
+      } : undefined
     },
     // Feature index (optional - top level, matches action-planning-agent expected access pattern)
     feature_index: file_exists(`${brainstormDir}/feature-specs/feature-index.json`) ? {
@@ -346,6 +351,10 @@ if (dir_exists(brainstormDir)) {
       exists: true,
       content: Read(`${brainstormDir}/feature-specs/feature-index.json`) || null
     } : undefined,
+    // Convenience: direct path to feature-index.json (avoids hardcoding in task-generate-agent)
+    feature_index_path: file_exists(`${brainstormDir}/feature-specs/feature-index.json`)
+      ? `${brainstormDir}/feature-specs/feature-index.json`
+      : undefined,
     // Feature spec files (optional - individual feature specifications)
     feature_specs: dir_exists(`${brainstormDir}/feature-specs`)
       ? glob(`${brainstormDir}/feature-specs/F-*-*.md`).map(file => ({
@@ -479,13 +488,18 @@ Calculate risk level based on:
     "synthesis_output": {
       "path": ".workflow/WFS-xxx/.brainstorming/synthesis-specification.md",
       "exists": true,
-      "content": "# Synthesis Specification\n\n## Cross-Role Integration\n..."
+      "content": "# Synthesis Specification\n\n## Cross-Role Integration\n...",
+      "feature_driven": {
+        "feature_index": ".workflow/WFS-xxx/.brainstorming/feature-specs/feature-index.json",
+        "feature_specs_dir": ".workflow/WFS-xxx/.brainstorming/feature-specs/"
+      }
     },
     "feature_index": {
       "path": ".workflow/WFS-xxx/.brainstorming/feature-specs/feature-index.json",
       "exists": true,
       "content": "{\"version\":\"1.0\",\"features\":[...]}"
     },
+    "feature_index_path": ".workflow/WFS-xxx/.brainstorming/feature-specs/feature-index.json",
     "feature_specs": [
       {
         "path": ".workflow/WFS-xxx/.brainstorming/feature-specs/F-001-auth.md",

.claude/commands/workflow/tools/task-generate-agent.md

@@ -280,7 +280,10 @@ Session ID: {session-id}
 MCP Capabilities: {exa_code, exa_web, code_index}
 
 ## FEATURE SPECIFICATIONS (conditional)
-If .workflow/active/{session-id}/.brainstorming/feature-specs/ exists:
+If context-package has brainstorm_artifacts.feature_index_path:
+  Feature Index: ${contextPackage.brainstorm_artifacts.feature_index_path}
+  Feature Spec Dir: ${contextPackage.brainstorm_artifacts.feature_index_path.replace('/feature-index.json', '/')}
+Else if .workflow/active/{session-id}/.brainstorming/feature-specs/ exists:
   Feature Index: .workflow/active/{session-id}/.brainstorming/feature-specs/feature-index.json
   Feature Spec Dir: .workflow/active/{session-id}/.brainstorming/feature-specs/
 
@@ -475,7 +478,10 @@ Session ID: {session-id}
 MCP Capabilities: {exa_code, exa_web, code_index}
 
 ## FEATURE SPECIFICATIONS (conditional)
-If .workflow/active/{session-id}/.brainstorming/feature-specs/ exists:
+If context-package has brainstorm_artifacts.feature_index_path:
+  Feature Index: ${contextPackage.brainstorm_artifacts.feature_index_path}
+  Feature Spec Dir: ${contextPackage.brainstorm_artifacts.feature_index_path.replace('/feature-index.json', '/')}
+Else if .workflow/active/{session-id}/.brainstorming/feature-specs/ exists:
   Feature Index: .workflow/active/{session-id}/.brainstorming/feature-specs/feature-index.json
   Feature Spec Dir: .workflow/active/{session-id}/.brainstorming/feature-specs/