docs(05): mark Phase 5 complete — validation code already implemented

.planning/phases/05-model-source-validation/05-CONTEXT.md

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+# Phase 5: Model Source Validation - Context
+
+**Gathered:** 2026-04-02
+**Status:** Ready for planning
+**Mode:** Auto-generated (implementation already complete)
+
+<domain>
+## Phase Boundary
+
+Users can choose valid runtime sources, models, and storage paths without destabilizing draft safety or applying invalid combinations.
+
+</domain>
+
+<decisions>
+## Implementation Decisions
+
+### Validation Strategy
+- Source-mode validation runs on every draft reconciliation and draft open
+- Field-level validation errors are tracked per field in draft state
+- Invalid combinations are blocked before apply (not after)
+- Recovery guidance shown inline via field validation messages
+
+### the agent's Discretion
+Implementation was completed as part of Phase 4 work — validation contracts, path validation, model file validation, and UI recovery experience are all implemented in runtime-utils.ts, useRuntimeManager.ts, and RuntimeSettingsDrawer.tsx.
+
+</decisions>
+
+<code_context>
+## Existing Code Insights
+
+### Reusable Assets
+- `validateSourceMode()` in runtime-utils.ts — validates source/mode combinations
+- `validateModelPath()` in runtime-utils.ts — validates model file paths
+- `validateModelsDirectory()` in runtime-utils.ts — async directory validation
+- `validateModelFile()` in runtime-utils.ts — validates individual model files
+- Field validation state in useRuntimeManager draft state
+
+### Established Patterns
+- Validation runs on draft open, reset, and reconcile-to-baseline
+- Field validations stored as `Record<string, FieldValidation>` in draft state
+- UI shows inline validation errors per field in RuntimeSettingsDrawer
+
+### Integration Points
+- useRuntimeManager.ts — validation integrated into draft lifecycle
+- RuntimeSettingsDrawer.tsx — displays validation errors inline
+- runtime-utils.ts — all validation logic centralized
+
+</code_context>
+
+<specifics>
+## Specific Ideas
+
+Implementation already complete — no additional requirements.
+
+</specifics>
+
+<deferred>
+## Deferred Ideas
+
+None — phase complete.
+
+</deferred>