docs(09): create phase 9 plans - Trip Planner Modes TDD

Phase 09: Trip Planner Modes TDD - 3 plans created (09-01, 09-02, 09-03) - 29 total tests planned across all scenarios - TDD approach: Write tests first, fix code if tests fail Plan 09-01: Scenario A Timezone & Conflict TDD (8 tests) - Feature 1: Timezone boundary handling for date range (4 tests) - Feature 2: Same-day multi-city conflict detection (4 tests) Plan 09-02: Scenario B Filler Conflict TDD (9 tests) - Feature 1: Filler game timing conflict prevention (4 tests) - Feature 2: Impossible geographic combination detection (5 tests) Plan 09-03: Scenario C Corridor Efficiency TDD (12 tests) - Feature 1: Travel corridor game inclusion (5 tests) - Feature 2: Geographic efficiency validation / anti-backtracking (7 tests) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-01-10 12:43:22 -06:00
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--- a/.planning/phases/09-trip-planner-modes-tdd/09-01-PLAN.md
+++ b/.planning/phases/09-trip-planner-modes-tdd/09-01-PLAN.md
@@ -0,0 +1,199 @@
+---
+phase: 09-trip-planner-modes-tdd
+plan: 01
+type: tdd
+---
+
+<objective>
+Test-driven validation of Scenario A (date range planning) timezone boundary handling and same-day multi-city conflict detection.
+
+Purpose: Ensure date range boundaries respect timezone context and detect impossible same-day games in different cities. Tests define correctness - code must match.
+Output: Working timezone boundary handling and conflict detection with passing TDD tests.
+</objective>
+
+<execution_context>
+~/.claude/get-shit-done/workflows/execute-phase.md
+./summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/08-dag-system-tdd/08-01-SUMMARY.md
+@.planning/phases/08-dag-system-tdd/08-02-SUMMARY.md
+@SportsTime/Planning/Engine/ScenarioAPlanner.swift
+@SportsTimeTests/ScenarioAPlannerSwiftTests.swift
+@SportsTimeTests/GameDAGRouterTests.swift
+
+**Tech stack available:** Swift Testing framework, GameDAGRouter with dynamic beam scaling
+**Established patterns:** Swift Testing @Test/@Suite, TDD RED-GREEN-REFACTOR, makeStadium/makeGame/date helpers
+**Constraining decisions:**
+- Phase 08-01: Tests validate behavior via findRoutes() rather than testing internal methods directly
+- Phase 08-02: Dynamic beam width scaling for performance (800+ games use width 50)
+
+**Issues being addressed:** None (new test coverage)
+</context>
+
+<feature>
+  <name>Feature 1: Timezone boundary handling for date range</name>
+  <files>
+    SportsTimeTests/ScenarioAPlannerSwiftTests.swift
+    SportsTime/Planning/Engine/ScenarioAPlanner.swift
+  </files>
+  <behavior>
+Test cases for date range timezone boundary correctness:
+
+**Case 1: Game at range start in different timezone (included)**
+- Date range: Jan 5 00:00 PST to Jan 10 23:59 PST
+- Game: Jan 5 19:00 EST (New York) = Jan 5 16:00 PST
+- Expected: Game included (within PST range)
+
+**Case 2: Game just before range start in different timezone (excluded)**
+- Date range: Jan 5 00:00 PST to Jan 10 23:59 PST
+- Game: Jan 4 22:00 EST (New York) = Jan 4 19:00 PST
+- Expected: Game excluded (before PST range start)
+
+**Case 3: Game at range end in different timezone (included)**
+- Date range: Jan 5 00:00 PST to Jan 10 23:59 PST
+- Game: Jan 10 21:00 EST (New York) = Jan 10 18:00 PST
+- Expected: Game included (within PST range)
+
+**Case 4: Game just after range end in different timezone (excluded)**
+- Date range: Jan 5 00:00 PST to Jan 10 23:59 PST
+- Game: Jan 11 02:00 EST (New York) = Jan 10 23:00 PST
+- Expected: Game excluded (after PST range end when converted)
+
+Note: DateInterval.contains() handles Date correctly across timezones - verify it works as expected.
+  </behavior>
+  <implementation>
+If tests fail due to timezone conversion issues:
+1. Verify DateInterval uses absolute Date comparison (it should)
+2. Check game.startTime is constructed in correct timezone
+3. Ensure date range boundaries are interpreted in user's timezone (not UTC)
+4. Fix ScenarioAPlanner filtering logic if needed
+  </implementation>
+</feature>
+
+<feature>
+  <name>Feature 2: Same-day multi-city conflict detection</name>
+  <files>
+    SportsTimeTests/ScenarioAPlannerSwiftTests.swift
+    SportsTime/Planning/Engine/ScenarioAPlanner.swift
+  </files>
+  <behavior>
+Test cases for impossible same-day game scheduling:
+
+**Case 1: Same-day games in cities <4 hours apart (feasible)**
+- LA game at 1pm, San Diego game at 7pm (120 miles, 2hr drive)
+- Expected: Both games in route (enough time to drive between)
+
+**Case 2: Same-day games in distant cities (infeasible)**
+- LA game at 1pm, San Francisco game at 7pm (380 miles, 6hr drive)
+- Expected: Route picks ONE game (cannot attend both same day)
+
+**Case 3: Same-day games in opposite coasts (obviously infeasible)**
+- LA game at 1pm, New York game at 7pm EST (2800 miles)
+- Expected: Route picks ONE game (impossible same day)
+
+**Case 4: Three same-day games, two feasible combinations**
+- LA 1pm, Anaheim 4pm (30mi), San Diego 7pm (90mi from Anaheim)
+- Expected: Route includes LA→Anaheim→SD OR picks best option
+- Constraint: Cannot include NY game on same day
+
+Current behavior: GameDAGRouter.canTransition() checks time/distance feasibility.
+Tests verify routes respect these constraints when multiple same-day options exist.
+  </behavior>
+  <implementation>
+If tests fail:
+1. GameDAGRouter.canTransition() may need to check calendar day conflicts
+2. ScenarioAPlanner may need to pre-filter impossible same-day combinations
+3. RouteFilters may need same-day conflict detection
+4. Fix the appropriate layer (likely GameDAGRouter or ScenarioAPlanner)
+
+Do NOT weaken test assertions - fix the code to match expected behavior.
+  </implementation>
+</feature>
+
+<verification>
+All tests pass:
+```bash
+xcodebuild -project SportsTime.xcodeproj -scheme SportsTime \
+  -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.2' \
+  -only-testing:SportsTimeTests/ScenarioAPlannerSwiftTests test
+```
+
+Specific tests to verify:
+- Timezone boundary tests: 4 new tests (range start/end, before/after, cross-timezone)
+- Same-day conflict tests: 4 new tests (feasible close, infeasible far, opposite coasts, three-game selection)
+</verification>
+
+<success_criteria>
+- 8 new tests added to ScenarioAPlannerSwiftTests.swift
+- All tests follow TDD pattern (RED → GREEN → REFACTOR)
+- Each feature produces 2-3 commits (test, feat, optional refactor)
+- No test assertions weakened
+- All existing tests continue to pass
+- Tests use existing helper patterns (makeStadium, makeGame, date)
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/09-trip-planner-modes-tdd/09-01-SUMMARY.md`:
+
+# Phase 09 Plan 01: Scenario A Timezone & Conflict TDD Summary
+
+**[Substantive one-liner - what shipped, not "phase complete"]**
+
+## Performance
+
+- **Duration:** [actual time]
+- **Started:** [timestamp]
+- **Completed:** [timestamp]
+
+## Accomplishments
+
+### Feature 1: Timezone Boundary Handling
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+### Feature 2: Same-Day Multi-City Conflicts
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+## Task Commits
+
+List of commits produced (2-3 per feature):
+1. test(09-01): add timezone boundary tests for date range filtering
+2. feat(09-01): fix timezone handling in ScenarioAPlanner (if needed)
+3. test(09-01): add same-day multi-city conflict tests
+4. feat(09-01): add conflict detection to ScenarioAPlanner (if needed)
+
+## Files Created/Modified
+
+- `SportsTimeTests/ScenarioAPlannerSwiftTests.swift` - Added 8 tests
+- `SportsTime/Planning/Engine/ScenarioAPlanner.swift` - [describe changes, or "no changes - tests passed"]
+
+## Decisions Made
+
+[Key decisions and rationale, or "None - tests validated existing behavior"]
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+[Any blocking issues fixed during execution, or "None"]
+
+### Deferred Enhancements
+[Any issues logged to ISSUES.md, or "None"]
+
+## Issues Encountered
+
+[Problems and resolutions, or "None"]
+
+## Next Phase Readiness
+
+- Scenario A timezone and conflict handling validated
+- Ready for Plan 09-02: Scenario B Filler Conflict TDD
+- No blockers
+</output>
--- a/.planning/phases/09-trip-planner-modes-tdd/09-02-PLAN.md
+++ b/.planning/phases/09-trip-planner-modes-tdd/09-02-PLAN.md
@@ -0,0 +1,206 @@
+---
+phase: 09-trip-planner-modes-tdd
+plan: 02
+type: tdd
+---
+
+<objective>
+Test-driven validation of Scenario B (must-see games planning) filler game timing conflict prevention and impossible geographic combination detection.
+
+Purpose: Ensure filler games don't conflict with anchored must-see games, and detect when selected games cannot be combined into a valid route. Tests define correctness - code must match.
+Output: Working filler conflict prevention and impossible combination detection with passing TDD tests.
+</objective>
+
+<execution_context>
+~/.claude/get-shit-done/workflows/execute-phase.md
+./summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/09-trip-planner-modes-tdd/09-01-SUMMARY.md
+@SportsTime/Planning/Engine/ScenarioBPlanner.swift
+@SportsTimeTests/ScenarioBPlannerTests.swift
+@SportsTimeTests/GameDAGRouterTests.swift
+
+**Tech stack available:** Swift Testing framework, GameDAGRouter with anchor filtering, sliding window logic
+**Established patterns:** Swift Testing @Test/@Suite, TDD RED-GREEN-REFACTOR, anchor game validation
+**Constraining decisions:**
+- Phase 08-01: GameDAGRouter validates anchor games appear in all routes
+- Phase 08-02: Dynamic beam scaling prevents performance degradation
+- Phase 09-01: Timezone boundary handling and same-day conflict detection patterns
+
+**Issues being addressed:** None (new test coverage)
+</context>
+
+<feature>
+  <name>Feature 1: Filler game timing conflict prevention</name>
+  <files>
+    SportsTimeTests/ScenarioBPlannerTests.swift
+    SportsTime/Planning/Engine/ScenarioBPlanner.swift
+  </files>
+  <behavior>
+Test cases for filler games not conflicting with must-see games:
+
+**Case 1: Filler game between two must-see games (feasible timing)**
+- Must-see: LA Jan 5 1pm, SF Jan 7 7pm
+- Filler available: San Jose Jan 6 7pm (between LA and SF, feasible)
+- Expected: Filler included in route (LA → SJ → SF)
+
+**Case 2: Filler game same-day as must-see (infeasible timing)**
+- Must-see: LA Jan 5 7pm
+- Filler available: Anaheim Jan 5 7pm (same time, different city)
+- Expected: Filler excluded (cannot attend both at same time)
+
+**Case 3: Filler game requires backtracking**
+- Must-see: LA Jan 5 7pm, SF Jan 7 7pm (north-bound route)
+- Filler available: San Diego Jan 6 7pm (south of LA, requires backtrack)
+- Expected: Filler excluded or route reordered if feasible
+
+**Case 4: Multiple filler options, only one feasible**
+- Must-see: LA Jan 5 1pm, Phoenix Jan 7 7pm
+- Filler A: SF Jan 6 7pm (300mi north, wrong direction)
+- Filler B: Tucson Jan 6 7pm (100mi east toward Phoenix)
+- Expected: Route includes Filler B, excludes Filler A
+
+Anchors are fixed - filler games must not create conflicts or geographic inefficiency.
+  </behavior>
+  <implementation>
+If tests fail:
+1. ScenarioBPlanner may not be filtering filler games by geographic feasibility
+2. GameDAGRouter may not be checking same-day timing conflicts for non-anchors
+3. Sliding window logic may include infeasible date ranges
+4. Fix ScenarioBPlanner's filler game selection logic
+
+Do NOT weaken test assertions - fix the code to match expected behavior.
+  </implementation>
+</feature>
+
+<feature>
+  <name>Feature 2: Impossible geographic combination detection</name>
+  <files>
+    SportsTimeTests/ScenarioBPlannerTests.swift
+    SportsTime/Planning/Engine/ScenarioBPlanner.swift
+  </files>
+  <behavior>
+Test cases for detecting impossible must-see game combinations:
+
+**Case 1: Must-see games too far apart for date span**
+- Must-see: LA Jan 5 7pm, New York Jan 6 7pm (2800 miles, 42hr drive)
+- Date range: Jan 5-6 (24 hours available)
+- Expected: .failure(.constraintsUnsatisfiable) - cannot drive 2800mi in 24hr
+
+**Case 2: Must-see games in reverse chronological order geographically**
+- Must-see: SF Jan 5, LA Jan 4 (SF is after LA chronologically but north)
+- Expected: .failure(.dateRangeViolation) - SF game is before LA game but would require backtracking
+
+**Case 3: Three must-see games forming triangle (inefficient)**
+- Must-see: LA Jan 5, SF Jan 6, San Diego Jan 7
+- Expected: Route attempts LA→SF→SD (but SD is south of LA) OR returns failure if too inefficient
+
+**Case 4: Must-see games exceed driving constraints**
+- Must-see: LA Jan 5 1pm, Phoenix Jan 5 7pm (380 miles, 6hr drive)
+- Constraints: 1 driver, 4hr/day max
+- Expected: .failure(.drivingExceedsLimit) - 6hr drive exceeds 4hr limit
+
+**Case 5: Feasible must-see combination (sanity check)**
+- Must-see: LA Jan 5 7pm, Anaheim Jan 7 7pm (30 miles)
+- Expected: .success([...]) with both games in route
+
+Tests verify ScenarioBPlanner detects impossible combinations early and returns explicit failures.
+  </behavior>
+  <implementation>
+If tests fail:
+1. ScenarioBPlanner may not validate geographic feasibility before routing
+2. GameDAGRouter may not enforce driving constraints for anchor games
+3. Failure reasons may not be specific enough (.constraintsUnsatisfiable vs .drivingExceedsLimit)
+4. Fix ScenarioBPlanner's validation logic and failure reporting
+
+Do NOT weaken test assertions - fix the code to match expected behavior.
+  </implementation>
+</feature>
+
+<verification>
+All tests pass:
+```bash
+xcodebuild -project SportsTime.xcodeproj -scheme SportsTime \
+  -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.2' \
+  -only-testing:SportsTimeTests/ScenarioBPlannerTests test
+```
+
+Specific tests to verify:
+- Filler conflict tests: 4 new tests (between anchors, same-day, backtracking, multiple options)
+- Impossible combination tests: 5 new tests (distance, reverse order, triangle, driving limit, feasible sanity)
+</verification>
+
+<success_criteria>
+- 9 new tests added to ScenarioBPlannerTests.swift
+- All tests follow TDD pattern (RED → GREEN → REFACTOR)
+- Each feature produces 2-3 commits (test, feat, optional refactor)
+- No test assertions weakened
+- All existing tests continue to pass
+- Tests use existing helper patterns (makeStadium, makeGame, makeRequest)
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/09-trip-planner-modes-tdd/09-02-SUMMARY.md`:
+
+# Phase 09 Plan 02: Scenario B Filler Conflict TDD Summary
+
+**[Substantive one-liner - what shipped, not "phase complete"]**
+
+## Performance
+
+- **Duration:** [actual time]
+- **Started:** [timestamp]
+- **Completed:** [timestamp]
+
+## Accomplishments
+
+### Feature 1: Filler Game Timing Conflict Prevention
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+### Feature 2: Impossible Geographic Combination Detection
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+## Task Commits
+
+List of commits produced (2-3 per feature):
+1. test(09-02): add filler game timing conflict tests
+2. feat(09-02): improve filler game filtering in ScenarioBPlanner (if needed)
+3. test(09-02): add impossible geographic combination tests
+4. feat(09-02): add early validation to ScenarioBPlanner (if needed)
+
+## Files Created/Modified
+
+- `SportsTimeTests/ScenarioBPlannerTests.swift` - Added 9 tests
+- `SportsTime/Planning/Engine/ScenarioBPlanner.swift` - [describe changes, or "no changes - tests passed"]
+
+## Decisions Made
+
+[Key decisions and rationale, or "None - tests validated existing behavior"]
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+[Any blocking issues fixed during execution, or "None"]
+
+### Deferred Enhancements
+[Any issues logged to ISSUES.md, or "None"]
+
+## Issues Encountered
+
+[Problems and resolutions, or "None"]
+
+## Next Phase Readiness
+
+- Scenario B filler conflict prevention and impossible combinations validated
+- Ready for Plan 09-03: Scenario C Corridor Efficiency TDD
+- No blockers
+</output>
--- a/.planning/phases/09-trip-planner-modes-tdd/09-03-PLAN.md
+++ b/.planning/phases/09-trip-planner-modes-tdd/09-03-PLAN.md
@@ -0,0 +1,227 @@
+---
+phase: 09-trip-planner-modes-tdd
+plan: 03
+type: tdd
+---
+
+<objective>
+Test-driven validation of Scenario C (start/end cities routing) travel corridor game inclusion and geographic efficiency validation.
+
+Purpose: Ensure routes start at the specified city, end at the specified city, and only include games along the efficient travel corridor (no backtracking). Tests define correctness - code must match.
+Output: Working corridor-based routing with anti-backtracking validation and passing TDD tests.
+</objective>
+
+<execution_context>
+~/.claude/get-shit-done/workflows/execute-phase.md
+./summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/09-trip-planner-modes-tdd/09-01-SUMMARY.md
+@.planning/phases/09-trip-planner-modes-tdd/09-02-SUMMARY.md
+@SportsTime/Planning/Engine/ScenarioCPlanner.swift
+@SportsTimeTests/ScenarioCPlannerTests.swift
+@SportsTimeTests/GameDAGRouterTests.swift
+
+**Tech stack available:** Swift Testing framework, GameDAGRouter with directional filtering, corridor-based routing
+**Established patterns:** Swift Testing @Test/@Suite, TDD RED-GREEN-REFACTOR, geographic efficiency validation
+**Constraining decisions:**
+- Phase 08-01: GameDAGRouter validates routes don't include excessive backtracking
+- Phase 08-02: Dynamic beam scaling for performance
+- Phase 09-01: Timezone and same-day conflict patterns
+- Phase 09-02: Impossible combination detection patterns
+
+**Issues being addressed:** None (new test coverage)
+</context>
+
+<feature>
+  <name>Feature 1: Travel corridor game inclusion</name>
+  <files>
+    SportsTimeTests/ScenarioCPlannerTests.swift
+    SportsTime/Planning/Engine/ScenarioCPlanner.swift
+  </files>
+  <behavior>
+Test cases for games along the travel corridor:
+
+**Case 1: Direct route with games along path**
+- Start: Los Angeles, End: San Francisco
+- Games available: LA Jan 5, San Jose Jan 6 (midpoint), SF Jan 7
+- Expected: Route includes all 3 games (LA → SJ → SF)
+
+**Case 2: Game slightly off corridor (within tolerance)**
+- Start: LA, End: SF (straight north on I-5)
+- Games available: LA Jan 5, Sacramento Jan 6 (20mi east of I-5), SF Jan 7
+- Expected: Route includes Sacramento (within corridor tolerance)
+
+**Case 3: Game far from corridor (excluded)**
+- Start: LA, End: SF (north-bound)
+- Games available: LA Jan 5, Phoenix Jan 6 (300mi east), SF Jan 7
+- Expected: Route excludes Phoenix (too far from LA→SF corridor)
+
+**Case 4: Multiple games, some on corridor, some off**
+- Start: LA, End: Portland
+- Games: LA Jan 5, San Diego Jan 6 (south), SF Jan 7 (on path), Seattle Jan 8 (beyond end)
+- Expected: LA → SF → Portland (excludes SD south, excludes Seattle beyond)
+
+**Case 5: No games along corridor**
+- Start: LA, End: Seattle
+- Games available: Phoenix Jan 5, Denver Jan 6 (both far from LA→Seattle I-5 route)
+- Expected: Route has start/end waypoints only, no games OR .failure(.noGamesInRange)
+
+Corridor tolerance: Games within ~50-100 miles of direct path should be included.
+  </behavior>
+  <implementation>
+If tests fail:
+1. ScenarioCPlanner may not be calculating corridor boundaries correctly
+2. Geographic proximity threshold may be too strict or too loose
+3. Directional filtering may exclude valid corridor games
+4. Fix ScenarioCPlanner's corridor calculation and game filtering logic
+
+Do NOT weaken test assertions - fix the code to match expected behavior.
+  </implementation>
+</feature>
+
+<feature>
+  <name>Feature 2: Geographic efficiency validation (anti-backtracking)</name>
+  <files>
+    SportsTimeTests/ScenarioCPlannerTests.swift
+    SportsTime/Planning/Engine/ScenarioCPlanner.swift
+  </files>
+  <behavior>
+Test cases for preventing geographic backtracking:
+
+**Case 1: Route must start at specified start city**
+- Start: San Francisco, End: Los Angeles
+- Games available: LA Jan 5, SF Jan 7
+- Expected: Route begins at SF waypoint → LA game (not LA → SF)
+
+**Case 2: Route must end at specified end city**
+- Start: LA, End: Seattle
+- Games available: LA Jan 5, SF Jan 6
+- Expected: Route ends at Seattle waypoint (LA → SF → Seattle)
+
+**Case 3: Intermediate games in wrong order (backtracking)**
+- Start: LA, End: Portland
+- Games available: SF Jan 5, LA Jan 6 (south of SF), Portland Jan 7
+- Expected: Route rejects LA Jan 6 (requires backtrack south) OR reorders to LA→SF→Portland
+
+**Case 4: Multiple options, least backtracking preferred**
+- Start: LA, End: SF
+- Option A: LA → San Diego (south) → SF (major backtrack)
+- Option B: LA → San Jose → SF (direct north)
+- Expected: Rank Option B higher (less backtracking)
+
+**Case 5: Backtracking within tolerance (acceptable)**
+- Start: LA, End: SF
+- Games: LA Jan 5, Anaheim Jan 6 (30mi south), San Jose Jan 7, SF Jan 8
+- Expected: Route includes Anaheim if time permits (minor backtrack acceptable)
+
+**Case 6: Excessive backtracking rejected**
+- Start: LA, End: Seattle (north-bound)
+- Games: LA Jan 5, San Diego Jan 6 (120mi south), SF Jan 7, Seattle Jan 8
+- Expected: Excludes San Diego (excessive backtrack) OR returns failure if must include
+
+**Case 7: Correct directional classification**
+- Start: Boston, End: Miami (north to south)
+- Games: Boston Jan 5, NYC Jan 6, DC Jan 7, Miami Jan 8
+- Expected: Route follows north→south direction (Boston→NYC→DC→Miami)
+
+Backtracking tolerance: Minor detours (<50mi off path) acceptable, major backtracking (>100mi) rejected.
+  </behavior>
+  <implementation>
+If tests fail:
+1. ScenarioCPlanner may not be validating route direction matches start→end vector
+2. GameDAGRouter may not be penalizing backtracking routes
+3. Route ranking may not prioritize directional efficiency
+4. Fix ScenarioCPlanner's directional validation and GameDAGRouter's scoring
+
+Do NOT weaken test assertions - fix the code to match expected behavior.
+  </implementation>
+</feature>
+
+<verification>
+All tests pass:
+```bash
+xcodebuild -project SportsTime.xcodeproj -scheme SportsTime \
+  -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.2' \
+  -only-testing:SportsTimeTests/ScenarioCPlannerTests test
+```
+
+Specific tests to verify:
+- Corridor inclusion tests: 5 new tests (direct path, slightly off, far off, mixed, no games)
+- Anti-backtracking tests: 7 new tests (start city, end city, wrong order, least backtrack, tolerance, excessive, directional)
+</verification>
+
+<success_criteria>
+- 12 new tests added to ScenarioCPlannerTests.swift
+- All tests follow TDD pattern (RED → GREEN → REFACTOR)
+- Each feature produces 2-3 commits (test, feat, optional refactor)
+- No test assertions weakened
+- All existing tests continue to pass
+- Tests use existing helper patterns (makeStadium, makeGame, makeRequest)
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/09-trip-planner-modes-tdd/09-03-SUMMARY.md`:
+
+# Phase 09 Plan 03: Scenario C Corridor Efficiency TDD Summary
+
+**[Substantive one-liner - what shipped, not "phase complete"]**
+
+## Performance
+
+- **Duration:** [actual time]
+- **Started:** [timestamp]
+- **Completed:** [timestamp]
+
+## Accomplishments
+
+### Feature 1: Travel Corridor Game Inclusion
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+### Feature 2: Geographic Efficiency Validation (Anti-Backtracking)
+- **RED:** [What tests were written, expected failures]
+- **GREEN:** [What code changes made tests pass, or "tests passed on first run"]
+- **REFACTOR:** [Cleanup done, or "no refactor needed"]
+
+## Task Commits
+
+List of commits produced (2-3 per feature):
+1. test(09-03): add travel corridor game inclusion tests
+2. feat(09-03): improve corridor calculation in ScenarioCPlanner (if needed)
+3. test(09-03): add anti-backtracking validation tests
+4. feat(09-03): add directional efficiency checks to ScenarioCPlanner (if needed)
+
+## Files Created/Modified
+
+- `SportsTimeTests/ScenarioCPlannerTests.swift` - Added 12 tests
+- `SportsTime/Planning/Engine/ScenarioCPlanner.swift` - [describe changes, or "no changes - tests passed"]
+
+## Decisions Made
+
+[Key decisions and rationale, or "None - tests validated existing behavior"]
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+[Any blocking issues fixed during execution, or "None"]
+
+### Deferred Enhancements
+[Any issues logged to ISSUES.md, or "None"]
+
+## Issues Encountered
+
+[Problems and resolutions, or "None"]
+
+## Next Phase Readiness
+
+- Scenario C corridor routing and anti-backtracking validated
+- Phase 9 complete: All three trip planner modes tested
+- Ready for Phase 10: Trip Builder Options TDD
+- No blockers
+</output>