Simplify system implementation
This commit is contained in:
yuxuanhui
@@ -1,327 +1,39 @@
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# Cross-Layer Thinking Guide
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# 跨层契约思考指南
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> **Purpose**: Think through data flow across layers before implementing.
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本仓库的最小链路是：
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---
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## The Problem
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**Most bugs happen at layer boundaries**, not within layers.
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Common cross-layer bugs:
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- API returns format A, frontend expects format B
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- Database stores X, service transforms to Y, but loses data
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- Multiple layers implement the same logic differently
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---
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## Before Implementing Cross-Layer Features
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### Step 1: Map the Data Flow
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Draw out how data moves:
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```
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Source → Transform → Store → Retrieve → Transform → Display
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```text
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FastAPI 路由
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→ Pydantic response model
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→ 同源 /api/v1 代理
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→ requestJson<T>
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→ feature *.types.ts / *.api.ts
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→ React Query hook
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→ 页面加载、错误、成功状态
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```
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For each arrow, ask:
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以系统状态为例，链路对应：
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- What format is the data in?
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- What could go wrong?
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- Who is responsible for validation?
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- 后端：`interfaces/http/router.py` 挂载 `/api/v1/system/status`，`interfaces/http/system.py` 返回 `SystemStatusResponse`。
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- 后端测试：`tests/test_system_http.py` 断言状态码和完整 JSON。
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- 前端：`features/system/api/system.api.ts` 使用 `/api/v1/system/status`，`system.types.ts` 描述字段，`system.query.ts` 管理缓存。
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- 页面测试：`system-status-page.test.tsx` 断言“运行正常”和环境文本。
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### Step 2: Identify Boundaries
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## 修改 HTTP 字段前
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| Boundary | Common Issues |
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| --------------------- | --------------------------------- |
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| API ↔ Service | Type mismatches, missing fields |
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| Service ↔ Database | Format conversions, null handling |
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| Backend ↔ Frontend | Serialization, date formats |
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| Component ↔ Component | Props shape changes |
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1. 找到后端响应模型、路由和现有契约测试。
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2. 找到 feature API 函数、TypeScript 类型、query hook 和页面分支。
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3. 确认开发 Vite 代理和生产 Nginx 仍覆盖该路径；浏览器代码保持同源路径。
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4. 同步更新后端 HTTP 测试和前端行为测试，再运行两端质量命令。
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### Step 3: Define Contracts
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## 常见跨层遗漏
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For each boundary:
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- 只修改 Pydantic 字段，没有修改 `*.types.ts`，导致 UI 仍读取旧形状。
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- 把 `/api/v1` 改成后端绝对 URL，绕过 `vite.config.ts` 和 Nginx 的同源代理。
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- 在页面内直接 `fetch`，绕过 `requestJson` 的 `ApiError` 和 `AbortSignal`。
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- 用 Zustand 缓存服务器响应，造成 React Query 缓存与全局 store 的双重事实来源。
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- 只测试请求成功，没有测试 `isPending`、`isError` 或字段缺失时的安全展示。
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- What is the exact input format?
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- What is the exact output format?
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- What errors can occur?
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## 边界验证
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---
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## Common Cross-Layer Mistakes
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### Mistake 1: Implicit Format Assumptions
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**Bad**: Assuming date format without checking
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**Good**: Explicit format conversion at boundaries
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### Mistake 2: Scattered Validation
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**Bad**: Validating the same thing in multiple layers
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**Good**: Validate once at the entry point
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### Mistake 3: Leaky Abstractions
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**Bad**: Component knows about database schema
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**Good**: Each layer only knows its neighbors
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### Mistake 4: Every Consumer Parses The Same Payload
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**Bad**: A command reads JSONL events and casts fields inline:
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```typescript
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const thread = (ev as { thread?: string }).thread;
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const labels = (ev as { labels?: string[] }).labels;
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```
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This looks local, but it means every consumer owns a private version of the
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event contract. The next field change will update one command and miss another.
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**Good**: Decode once at the event boundary, then export typed projections:
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```typescript
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if (!isThreadEvent(ev)) return false;
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return ev.thread === filter.thread;
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```
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**Rule**: For append-only logs, JSON streams, RPC payloads, or config files,
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create one owner for:
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- event / payload type definitions
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- type guards and normalization from `unknown`
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- metadata projections used by UI commands
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- reducers that replay state from the source of truth
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Rendering code may format fields, but it must not redefine the payload contract.
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---
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## Checklist for Cross-Layer Features
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Before implementation:
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- [ ] Mapped the complete data flow
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- [ ] Identified all layer boundaries
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- [ ] Defined format at each boundary
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- [ ] Decided where validation happens
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After implementation:
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- [ ] Tested with edge cases (null, empty, invalid)
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- [ ] Verified error handling at each boundary
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- [ ] Checked data survives round-trip
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- [ ] Checked that consumers import shared decoders / projections instead of
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casting payload fields locally
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- [ ] Checked that derived state points back to the source event identifier
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(`seq`, `id`, `version`) instead of inventing a second cursor
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---
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## Cross-Platform Template Consistency
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In Trellis, command templates (e.g., `record-session.md`) exist in **multiple platforms** with identical or near-identical content. This is a cross-layer boundary.
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### Checklist: After Modifying Any Command Template
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- [ ] Find all platforms with the same command: `find src/templates/*/commands/trellis/ -name "<command>.*"`
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- [ ] Update all platform copies (Markdown `.md` and TOML `.toml`)
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- [ ] For Gemini TOML: adapt line continuations (`\\` vs `\`) and triple-quoted strings
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- [ ] Run `/trellis:check-cross-layer` to verify nothing was missed
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**Real-world example**: Updated `record-session.md` in Claude to use `--mode record`, but forgot iFlow, Kilo, OpenCode, and Gemini — caught by cross-layer check.
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---
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## Generated Runtime Template Upgrade Consistency
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Some generated files are both documentation and runtime input. In Trellis,
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`.trellis/workflow.md` is parsed by `get_context.py`, `workflow_phase.py`,
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SessionStart filters, and per-turn hooks. Template changes must be validated
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against both fresh init and upgrade paths.
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### Checklist: After Modifying A Runtime-Parsed Template
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- [ ] Identify every runtime parser that reads the template, not just the file
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writer that installs it
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- [ ] Check whether relevant syntax lives outside obvious managed regions
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such as tag blocks
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- [ ] Verify fresh `init` output and a versioned `update` scenario that writes
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the older `.trellis/.version`
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- [ ] Add an upgrade regression using an older pristine template fixture, then
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assert the installed file reaches the current packaged shape
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- [ ] Update the backend spec that owns the runtime contract
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---
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## Versioned Documentation Boundary
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Versioned documentation is a cross-layer boundary: source paths, `docs.json`
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version routing, and the rendered version selector must all describe the same
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release line.
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### Checklist: Before Editing Versioned Docs
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- [ ] Identify the target release line: stable, beta, or RC
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- [ ] Verify the edited MDX path matches that line:
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- stable: `docs-site/{start,advanced,...}` and `docs-site/zh/{start,advanced,...}`
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- beta: `docs-site/beta/**` and `docs-site/zh/beta/**`
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- RC: `docs-site/rc/**` and `docs-site/zh/rc/**`
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- [ ] Verify `docs.json` navigation points the version label to the same paths
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- [ ] Grep the opposite tree for release-line-specific terms before committing
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- [ ] Treat beta content appearing under root release paths as a source-path bug,
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not a rendering bug
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**Real-world example**: A beta-only task workflow change documented
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`prd.md` + `design.md` + `implement.md`, task-creation consent, and Codex
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mode banners under root `start/` and `advanced/` paths. The docs site then
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served 0.6 beta behavior under the Release selector. The fix was to restore root
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release docs, move the 0.6 content to `beta/` and `zh/beta/`, and add a grep
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audit for beta markers against the root release tree.
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**Real-world example**: Codex inline mode changed workflow platform markers from
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`[Codex]` / `[Kilo, Antigravity, Windsurf]` to `[codex-sub-agent]` /
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`[codex-inline, Kilo, Antigravity, Windsurf]`. Fresh init was correct, but
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`trellis update` only merged `[workflow-state:*]` blocks and preserved stale
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markers outside those blocks. Result: upgraded projects got new hook scripts
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but old workflow routing, so `get_context.py --mode phase --platform codex`
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could return empty Phase 2.1 detail.
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---
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## Mode-Detection Probe Checklist
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When a CLI auto-detects a mode by probing a remote resource (e.g., checking if `index.json` exists to decide marketplace vs direct download):
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### Before implementing:
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- [ ] Probe runs in **ALL** code paths that use the result (interactive, `-y`, `--flag` combos)
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- [ ] 404 vs transient error are distinguished — don't treat both as "not found"
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- [ ] Transient errors **abort or retry**, never silently switch modes
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- [ ] Shared state (caches, prefetched data) is **reset** when context changes (e.g., user switches source)
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- [ ] **Shortcut paths** (e.g., `--template` skipping picker) must have the same error-handling quality as the probed path — check that downstream functions don't call catch-all wrappers
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### After implementing:
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- [ ] Trace every path from probe result to the mode-decision branch — no fallthrough
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- [ ] External format contracts (giget URI, raw URLs) are tested or at least documented as comments
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- [ ] Metadata reads consume a complete response or use a streaming parser — never parse a fixed-size prefix as full JSON
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- [ ] When reconstructing a composite identifier from parsed parts, verify **all** fields are included and in the **correct position** (e.g., `provider:repo/path#ref` not `provider:repo#ref/path`)
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- [ ] Verify that **action functions** called after a shortcut don't internally use the old catch-all fetch — they must use the probe-quality variant when error distinction matters
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**Real-world example**: Custom registry flow had 8 bugs across 3 review rounds: (1) probe only ran in interactive mode, (2) transient errors fell through to wrong mode, (3) giget URI had `#ref` in wrong position, (4) prefetched templates leaked across source switches, (5) `--template` shortcut bypassed probe but `downloadTemplateById` internally used catch-all `fetchTemplateIndex`, turning timeouts into "Template not found".
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**Real-world example**: Agent-session update hints fetched npm `latest` metadata with `response.read(4096)` and then parsed it as complete JSON. The `@mindfoldhq/trellis` package metadata exceeded 4 KB, so the JSON was truncated, parse failed silently, and the first session injection showed no update hint. Fix: read the complete response before parsing, and add a regression where `version` is followed by an 8 KB metadata tail.
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---
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## Cross-Platform Template Consistency
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In Trellis, command templates (e.g., `record-session.md`) exist in **multiple platforms** with identical or near-identical content. This is a cross-layer boundary.
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### Checklist: After Modifying Any Command Template
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- [ ] Find all platforms with the same command: `find src/templates/*/commands/trellis/ -name "<command>.*"`
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- [ ] Update all platform copies (Markdown `.md` and TOML `.toml`)
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- [ ] For Gemini TOML: adapt line continuations (`\\` vs `\`) and triple-quoted strings
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- [ ] Run `/trellis:check-cross-layer` to verify nothing was missed
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**Real-world example**: Updated `record-session.md` in Claude to use `--mode record`, but forgot iFlow, Kilo, OpenCode, and Gemini — caught by cross-layer check.
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---
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## Generated Runtime Template Upgrade Consistency
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Some generated files are both documentation and runtime input. In Trellis,
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`.trellis/workflow.md` is parsed by `get_context.py`, `workflow_phase.py`,
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SessionStart filters, and per-turn hooks. Template changes must be validated
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against both fresh init and upgrade paths.
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### Checklist: After Modifying A Runtime-Parsed Template
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- [ ] Identify every runtime parser that reads the template, not just the file
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writer that installs it
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- [ ] Check whether relevant syntax lives outside obvious managed regions
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such as tag blocks
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- [ ] Verify fresh `init` output and a versioned `update` scenario that writes
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the older `.trellis/.version`
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- [ ] Add an upgrade regression using an older pristine template fixture, then
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assert the installed file reaches the current packaged shape
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- [ ] Update the backend spec that owns the runtime contract
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||||
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**Real-world example**: Codex inline mode changed workflow platform markers from
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`[Codex]` / `[Kilo, Antigravity, Windsurf]` to `[codex-sub-agent]` /
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||||
`[codex-inline, Kilo, Antigravity, Windsurf]`. Fresh init was correct, but
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`trellis update` only merged `[workflow-state:*]` blocks and preserved stale
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markers outside those blocks. Result: upgraded projects got new hook scripts
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but old workflow routing, so `get_context.py --mode phase --platform codex`
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could return empty Phase 2.1 detail.
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---
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## Mode-Detection Probe Checklist
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When a CLI auto-detects a mode by probing a remote resource (e.g., checking if `index.json` exists to decide marketplace vs direct download):
|
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|
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### Before implementing:
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- [ ] Probe runs in **ALL** code paths that use the result (interactive, `-y`, `--flag` combos)
|
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- [ ] 404 vs transient error are distinguished — don't treat both as "not found"
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||||
- [ ] Transient errors **abort or retry**, never silently switch modes
|
||||
- [ ] Shared state (caches, prefetched data) is **reset** when context changes (e.g., user switches source)
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||||
- [ ] **Shortcut paths** (e.g., `--template` skipping picker) must have the same error-handling quality as the probed path — check that downstream functions don't call catch-all wrappers
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### After implementing:
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- [ ] Trace every path from probe result to the mode-decision branch — no fallthrough
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- [ ] External format contracts (giget URI, raw URLs) are tested or at least documented as comments
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- [ ] Metadata reads consume a complete response or use a streaming parser — never parse a fixed-size prefix as full JSON
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||||
- [ ] When reconstructing a composite identifier from parsed parts, verify **all** fields are included and in the **correct position** (e.g., `provider:repo/path#ref` not `provider:repo#ref/path`)
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- [ ] Verify that **action functions** called after a shortcut don't internally use the old catch-all fetch — they must use the probe-quality variant when error distinction matters
|
||||
|
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**Real-world example**: Custom registry flow had 8 bugs across 3 review rounds: (1) probe only ran in interactive mode, (2) transient errors fell through to wrong mode, (3) giget URI had `#ref` in wrong position, (4) prefetched templates leaked across source switches, (5) `--template` shortcut bypassed probe but `downloadTemplateById` internally used catch-all `fetchTemplateIndex`, turning timeouts into "Template not found".
|
||||
|
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**Real-world example**: Agent-session update hints fetched npm `latest` metadata with `response.read(4096)` and then parsed it as complete JSON. The `@mindfoldhq/trellis` package metadata exceeded 4 KB, so the JSON was truncated, parse failed silently, and the first session injection showed no update hint. Fix: read the complete response before parsing, and add a regression where `version` is followed by an 8 KB metadata tail.
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---
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## When to Create Flow Documentation
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Create detailed flow docs when:
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- Feature spans 3+ layers
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- Multiple teams are involved
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- Data format is complex
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- Feature has caused bugs before
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---
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## Event Log / Projection Boundary
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Append-only logs are cross-layer contracts. A single event travels through:
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```
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CLI input → event writer → events.jsonl → reader → filter → reducer → display
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```
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### Checklist: After Adding A New Event Kind Or Field
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- [ ] Add the event kind to the central event taxonomy
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- [ ] Add a typed event variant or type guard at the event layer
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- [ ] Add normalization helpers for array/object fields that come from
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user input or JSON
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- [ ] Keep `seq` / `id` assignment in the event writer only
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- [ ] Make filters and reducers consume the typed event guard, not local casts
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- [ ] Make display code consume reducer output or typed events, not raw JSON
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- [ ] Add at least one regression that proves history replay and live filtering
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use the same filter model
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**Real-world example**: Thread channels added `kind: "thread"`, `description`,
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`context`, labels, and `lastSeq`. The first implementation replayed thread
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state correctly, but several commands still re-parsed event payload fields with
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local casts. The fix was to make the core event layer own `ThreadChannelEvent`
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and `isThreadEvent`, make `reduceChannelMetadata` the only channel metadata
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projection, and make `reduceThreads` the only thread replay reducer.
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提交前至少回答：输入在哪里解析？错误在哪里转换？状态由谁拥有？字段是否在后端、客户端类型和 UI 测试中一致？如果答案不清楚，先补充契约或拆分边界，再实现功能。
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Reference in New Issue
Block a user