docs: .env.example 补充 WORKSPACE_MAX_AGE_DAYS 说明

[lishuceo]

背景

线上工作区被清理的实际窗口是 3 天（src/config.ts 中 WORKSPACE_MAX_AGE_DAYS 默认值），但 .env.example 里完全没有提到这个变量，容易被误认为是一周或更久。

改动

• .env.example 工作区配置段补充 WORKSPACE_MAX_AGE_DAYS 注释，说明默认 3 天，且该值同时决定 thread session 的空闲过期时间（过期后其自动创建的工作区目录一并删除）。

纯文档改动，无代码逻辑变更。线上部署侧已单独把该值调整为 30 天（.env 不入库）。

🤖 Generated with Claude Code

[github-actions]

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Claude Code Review

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• Verify claims in the new .env.example comment against source
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✅ Approved

Pure documentation change. I verified every factual claim in the new comment against the source — all three are accurate.

Verification

Claim in .env.example	Source	Status
默认 3	src/config.ts:125 — parseInt(process.env.WORKSPACE_MAX_AGE_DAYS || '3', 10)	✅
同时决定 thread session 的空闲过期时间	src/session/manager.ts:237-240 — threadMaxIdleMs = config.workspace.maxAgeDays * 24*60*60*1000, used as the cutoff for deleteExpiredThreadSessionsByCutoff	✅
其自动创建的工作区目录一并清理	src/session/manager.ts:245-261 — deletion is gated on isAutoWorkspacePath(thread.workingDir), so user-specified paths are preserved	✅

The "自动创建的" qualifier is a good catch — without it the comment would over-promise, since manually-specified workingDir values are deliberately left alone. config.workspace.maxAgeDays has exactly one consumer (session/manager.ts:237), which also feeds cleanupOrphanWorkspaces() at line 267, so the documented scope is complete.

Placement inside the === 工作区配置 === block next to WORKSPACE_BASE_DIR / WORKSPACE_BRANCH_PREFIX is consistent with the file's existing convention (commented-out line preceded by an explanatory comment, default value inlined).

Notes (non-blocking, no action requested)

• No tests needed — the repo's testing policy in CLAUDE.md applies to feat/fix commits, not docs-only changes.
• Pre-existing gap, not introduced here: REPO_CACHE_MAX_AGE_DAYS (default 30, src/config.ts:133), REPO_CACHE_MAX_SIZE_GB, and REPO_CACHE_FETCH_INTERVAL_MIN are also undocumented in .env.example, which documents only REPO_CACHE_DIR. Worth a follow-up if you want the same clarity for the cache knobs. Fix this →

No issues found. Zero risk to merge.
· Branch: feat/claude-session-e9544f