fix: parseFrontmatter型バリデーション + repetition共有util抽出

[terisuke]

What

PR #56 のレビュー残り2件を修正。

Why

• parseFrontmatter() が invalid type を無検証でキャストしていた
• repetition.test.ts が production コードを import せず独自実装していた

Closes #69

Changes

1. memory/file.ts: Memory.TYPES に対するバリデーション追加
2. session/repetition.ts: 新規共有util
3. session/processor.ts: import に置換
4. test 更新

Review

• code-reviewer Agent: CRITICAL/HIGH 0
• Codex CLI: No issues in PR A

Test plan

• bun test test/memory/file.test.ts — 19 pass
• bun test test/session/repetition.test.ts — 8 pass
• typecheck 13/13 pass

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[Copilot]

Pull request overview

This PR addresses remaining review items from PR #56 by adding runtime validation for user-editable memory frontmatter types and by extracting the repetition-detection logic into a shared production util that tests can import.

Changes:

• Add validation in parseFrontmatter() to reject unknown type values (based on Memory.TYPES).
• Extract detectRepetition (+ constants) into src/session/repetition.ts and reuse it from SessionProcessor and tests.
• Update/add tests to cover valid/invalid/missing memory type parsing and to import the shared repetition util.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/opencode/src/memory/file.ts	Validate frontmatter type against Memory.TYPES before casting.
packages/opencode/src/session/repetition.ts	New shared repetition-detection util + exported constants.
packages/opencode/src/session/processor.ts	Replace inlined repetition logic with imports from ./repetition.
packages/opencode/test/session/repetition.test.ts	Switch test to import production detectRepetition + constants.
packages/opencode/test/memory/file.test.ts	Add coverage for valid/invalid/missing frontmatter type.

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[Copilot]

These two imports come from the same module; consider combining them into a single import to reduce redundancy and keep imports easier to maintain.

Suggested change

	import { detectRepetition } from "../../src/session/repetition"
	import { REPETITION_THRESHOLD, REPETITION_WINDOW } from "../../src/session/repetition"
	import { detectRepetition, REPETITION_THRESHOLD, REPETITION_WINDOW } from "../../src/session/repetition"