diff --git a/.planning/ROADMAP.md b/.planning/ROADMAP.md
index cf5823eb..433b88f0 100644
--- a/.planning/ROADMAP.md
+++ b/.planning/ROADMAP.md
@@ -239,7 +239,7 @@ Plans:
 - [x] 18-01: File I/O routes (workflow, save-generation)
 - [x] 18-02: LLM route (Google, OpenAI providers)
 - [x] 18-03: Generate route (Gemini provider)
-- [ ] 18-04: Generate route (Replicate, fal.ai providers)
+- [x] 18-04: Generate route (Replicate, fal.ai providers)
 - [ ] 18-05: Models route (caching, aggregation)
 
 #### Phase 19: Type Refactoring
@@ -319,7 +319,7 @@ Phases execute in numeric order: 1 → 2 → ... → 14 → 15 → 16 → 17 →
 | 15. Test Infrastructure | v1.2 | 1/1 | Complete | 2026-01-12 |
 | 16. Store Modularization | v1.2 | 1/1 | Complete | 2026-01-12 |
 | 17. Component Tests | v1.2 | 11/11 | Complete | 2026-01-13 |
-| 18. API Route Tests | v1.2 | 3/5 | In progress | - |
+| 18. API Route Tests | v1.2 | 4/5 | In progress | - |
 | 19. Type Refactoring | v1.2 | 0/? | Not started | - |
 | 20. Integration Tests | v1.2 | 0/? | Not started | - |
 | 21. Fix Image Input & Deduplication | v1.2 | 0/? | Not started | - |
diff --git a/.planning/STATE.md b/.planning/STATE.md
index 420cae92..0c635786 100644
--- a/.planning/STATE.md
+++ b/.planning/STATE.md
@@ -10,11 +10,11 @@ See: .planning/PROJECT.md (updated 2026-01-09)
 ## Current Position
 
 Phase: 18 of 22 (API Route Tests)
-Plan: 3 of 5 in current phase
+Plan: 4 of 5 in current phase
 Status: In progress
-Last activity: 2026-01-13 - Completed 18-03-PLAN.md
+Last activity: 2026-01-13 - Completed 18-04-PLAN.md
 
-Progress: █████████░ 91%
+Progress: █████████░ 92%
 
 ## Performance Metrics
 
@@ -128,6 +128,6 @@ Recent decisions affecting current work:
 ## Session Continuity
 
 Last session: 2026-01-13
-Stopped at: Completed 18-03-PLAN.md (Generate route Gemini tests)
+Stopped at: Completed 18-04-PLAN.md (Generate route Replicate/fal.ai tests)
 Resume file: None
-Next action: Execute Plan 18-04 (run /gsd:execute-plan .planning/phases/18-api-route-tests/18-04-PLAN.md)
+Next action: Execute Plan 18-05 (run /gsd:execute-plan .planning/phases/18-api-route-tests/18-05-PLAN.md)
diff --git a/.planning/phases/18-api-route-tests/18-04-SUMMARY.md b/.planning/phases/18-api-route-tests/18-04-SUMMARY.md
new file mode 100644
index 00000000..660f388a
--- /dev/null
+++ b/.planning/phases/18-api-route-tests/18-04-SUMMARY.md
@@ -0,0 +1,92 @@
+---
+phase: 18-api-route-tests
+plan: 04
+subsystem: api
+tags: [replicate, fal.ai, testing, vitest, fetch-mocking]
+
+# Dependency graph
+requires:
+  - phase: 18-api-route-tests (18-03)
+    provides: Gemini provider test patterns and mock helpers
+provides:
+  - Complete generate route test coverage for all three providers
+  - Replicate polling logic tests
+  - fal.ai response format tests
+affects: [19-type-refactoring, 20-integration-tests]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [global fetch mocking for external APIs, Replicate polling simulation]
+
+key-files:
+  created: []
+  modified: [src/app/api/generate/__tests__/route.test.ts]
+
+key-decisions:
+  - "Mock global.fetch for external API calls (Replicate, fal.ai) vs SDK mocking for Gemini"
+  - "Schema fetch mocking required for fal.ai tests without dynamicInputs"
+
+patterns-established:
+  - "Replicate prediction polling simulation with status transitions"
+  - "fal.ai multi-format response testing (images array, image object, video object, output string)"
+
+issues-created: []
+
+# Metrics
+duration: 7min
+completed: 2026-01-13
+---
+
+# Phase 18 Plan 04: Generate Route Replicate/fal.ai Tests Summary
+
+**Complete generate route test coverage with Replicate polling, fal.ai response formats, and rate limit handling**
+
+## Performance
+
+- **Duration:** 7 min
+- **Started:** 2026-01-13T02:39:09Z
+- **Completed:** 2026-01-13T02:46:10Z
+- **Tasks:** 2
+- **Files modified:** 1
+
+## Accomplishments
+
+- Added 10 tests for Replicate provider covering image/video generation, polling, timeouts, and large video URL returns
+- Added 15 tests for fal.ai provider covering multiple response formats, rate limits, and dynamic input filtering
+- All 55 generate route tests now pass covering all three providers (Gemini, Replicate, fal.ai)
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add generate route tests for Replicate provider** - `c3bbed9` (test)
+2. **Task 2: Add generate route tests for fal.ai provider** - `b2660d3` (test)
+
+**Plan metadata:** (pending this commit)
+
+## Files Created/Modified
+
+- `src/app/api/generate/__tests__/route.test.ts` - Added Replicate provider tests (+548 lines), Added fal.ai provider tests (+613 lines)
+
+## Decisions Made
+
+- Used global.fetch mocking for Replicate and fal.ai (external APIs) vs SDK mocking for Gemini
+- Added schema fetch mocking for fal.ai tests that don't use dynamicInputs (getFalInputMapping makes API calls)
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None
+
+## Next Phase Readiness
+
+- Generate route fully tested across all providers
+- Ready for 18-05-PLAN.md (Models route tests)
+
+---
+*Phase: 18-api-route-tests*
+*Completed: 2026-01-13*