docs(08-01): complete GameDAGRouter edge cases plan

Plan 08-01 complete:
- 17 TDD tests for GameDAGRouter edge cases
- canTransition boundary validation tests
- Anchor filtering and repeat city handling tests

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/phases/08-dag-system-tdd/08-01-SUMMARY.md

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+---
+phase: 08-dag-system-tdd
+plan: 01
+subsystem: testing
+tags: [swift-testing, tdd, dag-routing, trip-planning]
+
+requires:
+  - phase: 07-testing-docs
+    provides: Testing infrastructure and patterns
+provides:
+  - GameDAGRouter edge case test suite (17 tests)
+  - canTransition boundary validation tests
+  - TDD workflow for routing algorithm
+affects: [08-02, 09-trip-planner-modes, trip-planning-engine]
+
+tech-stack:
+  added: []
+  patterns: [swift-testing-tdd, game-routing-tests]
+
+key-files:
+  created: [SportsTimeTests/GameDAGRouterTests.swift]
+  modified: [SportsTimeTests/SportsTimeTests.swift]
+
+key-decisions:
+  - "Used Swift Testing framework (@Test, #expect) consistent with existing test patterns"
+  - "Tests validate behavior via findRoutes() rather than testing canTransition() directly"
+
+patterns-established:
+  - "GameDAGRouter test pattern: makeStadium/makeGame/date helpers for consistent test data"
+  - "Feasibility tests: verify route combinations exist or don't exist based on distance/time constraints"
+
+issues-created: []
+
+duration: 25min
+completed: 2026-01-10
+---
+
+# Phase 8 Plan 01: GameDAGRouter Edge Cases Summary
+
+**17 TDD tests validating GameDAGRouter edge cases, anchor filtering, repeat city handling, and canTransition time/distance boundaries**
+
+## Performance
+
+- **Duration:** 25 min
+- **Started:** 2026-01-10T17:37:21Z
+- **Completed:** 2026-01-10T18:02:00Z
+- **Tasks:** 3 (Task 2 auto-completed - tests passed on first run)
+- **Files modified:** 2
+
+## Accomplishments
+- Created 10 edge case tests covering empty inputs, single games, anchor filtering, and repeat city handling
+- Added 7 canTransition boundary tests for time buffers and distance constraints
+- Removed broken DayCardTests that referenced deleted types (cleanup)
+- All 17 tests pass, validating GameDAGRouter correctness
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Create GameDAGRouterTests with edge case tests** - `a4db9a9` (test)
+2. **Task 2: Fix any failing edge case tests** - N/A (all passed on first run)
+3. **Task 3: Add canTransition boundary tests** - `02cb09f` (test)
+
+**Plan metadata:** (pending)
+
+## Files Created/Modified
+- `SportsTimeTests/GameDAGRouterTests.swift` - New test file with 17 edge case tests for GameDAGRouter
+- `SportsTimeTests/SportsTimeTests.swift` - Removed broken DayCardTests (types no longer exist)
+
+## Decisions Made
+- Used Swift Testing framework consistent with existing tests (ScenarioBPlannerTests)
+- Test canTransition() logic indirectly through findRoutes() behavior rather than making it public
+- Corrected initial borderline timing test (GameEndBuffer) after verifying actual haversine distances
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 3 - Blocking] Fixed pre-existing broken tests**
+- **Found during:** Task 1 (running tests)
+- **Issue:** SportsTimeTests.swift referenced DayCard and DayConflictInfo types that were removed in previous refactor
+- **Fix:** Removed broken DayCardTests struct (11 tests), kept working DuplicateGameIdTests
+- **Files modified:** SportsTimeTests/SportsTimeTests.swift
+- **Verification:** Build succeeds, all tests run
+- **Committed in:** 02cb09f (combined with Task 3)
+
+**2. [Rule 1 - Auto-fix] Corrected borderline test case**
+- **Found during:** Task 3 (running boundary tests)
+- **Issue:** GameEndBuffer test expected infeasible but actual haversine calculation showed 2.45hr drive fits in 2.5hr window
+- **Fix:** Adjusted test timing to be clearly infeasible (1.5hr available for 2.45hr drive)
+- **Files modified:** SportsTimeTests/GameDAGRouterTests.swift
+- **Verification:** Test now correctly validates buffer behavior
+- **Committed in:** 02cb09f
+
+### Deferred Enhancements
+
+None - all tests pass, no issues logged.
+
+---
+
+**Total deviations:** 2 auto-fixed (1 blocking pre-existing issue, 1 test refinement), 0 deferred
+**Impact on plan:** Auto-fixes necessary for build success. No scope creep.
+
+## Issues Encountered
+- Pre-existing test failure in ScenarioAPlannerSwiftTests (plan_StopDepartureDate_IsLastGameDate) - unrelated to this phase, not investigated
+
+## Next Phase Readiness
+- GameDAGRouter edge cases validated, ready for Plan 08-02 (performance with large datasets)
+- Test patterns established for future DAG routing tests
+- No blockers
+
+---
+*Phase: 08-dag-system-tdd*
+*Plan: 01*
+*Completed: 2026-01-10*