diff --git a/docs/architecture.md b/docs/architecture.md new file mode 100644 index 0000000..8955934 --- /dev/null +++ b/docs/architecture.md @@ -0,0 +1,213 @@ +# ai-cli-dispatch Architecture + +This document describes the internal design of `ai-cli-dispatch`, the module breakdown, data flow, key design decisions, and how to extend the tool. + +## Module Breakdown + +```text +src/ +├── cli.ts — Entry point: argument parsing, command routing, I/O formatting +├── types.ts — Shared types and error classes +├── constants.ts — Client name registry and platform helpers +├── config.ts — Layered configuration resolution (flags → env → file → PATH) +├── detect.ts — Client discovery: binary lookup and version extraction +├── dispatch.ts — Prompt-to-client resolution (explicit flag → keywords → default) +└── execute.ts — Subprocess spawning, stdout/stderr capture, timeout handling +``` + +### Responsibilities + +| Module | Responsibility | +|---|---| +| `cli.ts` | Parses `argv` with `minimist`, routes to `list` / `run` / `dispatch`, prints JSON or text output, and controls the process exit code. | +| `types.ts` | Defines `ClientName`, `ClientInfo`, `ExecResult`, `ToolConfig`, and the error hierarchy (`ClientNotFoundError`, `ExecError`). | +| `constants.ts` | Holds the canonical `CLIENT_NAMES` array and `isWindows()` helper used by discovery and config. | +| `config.ts` | Resolves per-client binary paths and the optional `defaultClient` from four layered sources. | +| `detect.ts` | Locates each client binary on `PATH`, falls back to a manual directory scan, and invokes `--version` to extract a semver string. | +| `dispatch.ts` | Chooses the target client from a prompt string using ordered keyword matching, with overrides for explicit `--client` and `defaultClient`. | +| `execute.ts` | Spawns the chosen client with its native argument shape, buffers `stdout`/`stderr`, enforces a timeout, and returns an `ExecResult` or throws a typed error. | + +## Data Flow + +A typical `dispatch` invocation flows through four stages: + +``` +┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ +│ detect │ ──► │ config │ ──► │ dispatch │ ──► │ execute │ +└─────────────┘ └─────────────┘ └─────────────┘ └─────────────┘ + │ │ │ │ + which/where flags/env/file keyword scan spawn child + PATH walk defaultClient --client override capture output + --version fallback default timeout / exitCode +``` + +### 1. Detect + +`detectClients()` iterates over `CLIENT_NAMES` and attempts to locate each binary: + +1. Invoke `which ` (or `where ` on Windows). +2. If that fails, walk `PATH` segments manually and test `existsSync()`. +3. If a binary is found, run ` --version` and parse the first semver-like match. + +Result: an array of `ClientInfo` objects with `name`, `found`, `path`, and `version`. + +### 2. Config + +`resolveConfig()` builds a `ResolvedConfig` by layering sources (highest to lowest precedence): + +1. **CLI flags** — `--codex-path`, `--claude-path`, `--opencode-path`, `--default-client` +2. **Environment variables** — `AI_CLI_CODEX_PATH`, `AI_CLI_CLAUDE_PATH`, `AI_CLI_OPENCODE_PATH`, `AI_CLI_DEFAULT_CLIENT` +3. **Config file** — `~/.openclaw/ai-cli-dispatch.json` (`paths` and `defaultClient` keys) +4. **PATH discovery** — `which`/`where` fallback via `defaultWhichSync()` + +Only values for the three known `ClientName` entries are accepted; unknown `defaultClient` values are ignored. + +### 3. Dispatch + +`resolveClient(prompt, config)` decides which client to use: + +1. If `config.client` is a valid `ClientName`, return it immediately. +2. Lower-case the prompt and scan for substrings in order: + - `"open code"` → `opencode` + - `"claude"` → `claude` + - `"codex"` → `codex` + - `"opencode"` → `opencode` +3. If no keyword matches, return `config.defaultClient` or `null`. + +This ordering intentionally prioritizes `"open code"` before `"opencode"` so the spaced natural-language variant wins. + +### 4. Execute + +`executePrompt(client, prompt, options)` runs the selected client: + +1. Reject empty or whitespace-only prompts with `ExecError`. +2. Validate that an explicit `clientPath` exists on disk (if provided). +3. Map the client to its native argument array via `CLIENT_ARGS`: + - `codex` → `["exec", prompt]` + - `claude` → `["-p", prompt]` + - `opencode` → `[prompt]` +4. `spawn()` the process with `shell: false`. +5. Buffer `stdout` and `stderr` via `"data"` listeners. +6. Start a `setTimeout`; if it fires, `child.kill()` is sent. +7. On `close`, resolve with `{ stdout, stderr, exitCode }`. +8. On `error`, reject with `ClientNotFoundError` for `ENOENT` or `ExecError` for anything else. +9. On timeout, reject with `ExecError` containing the buffered output so far. + +The default timeout is **5 minutes** (`300_000` ms). + +## Design Decisions + +### Coexistence with ACP + +`ai-cli-dispatch` is intentionally **not** an ACP agent. It is a thin, local subprocess wrapper with no session state, no thread binding, and no orchestrator protocol. + +- Use `ai-cli-dispatch` when you need a quick, one-shot CLI execution on the gateway host. +- Use ACP (`docs/openclaw-acp-orchestration.md`) when you need session-bound coding harnesses, multi-turn review, or orchestrator-managed verification gates. + +This separation keeps the dispatcher small and avoids duplicating ACP’s scheduling, context persistence, and review-loop responsibilities. + +### Keyword Dispatch vs NLP + +Client resolution uses deterministic substring matching instead of natural-language parsing or an LLM call. + +**Rationale:** +- **Speed:** No network round-trip or model load; resolution is synchronous and sub-millisecond. +- **Predictability:** The same prompt always resolves to the same client. There is no temperature, context window, or model-version drift. +- **Debuggability:** A user can read the ordered keyword list and know exactly why a given prompt resolved to a given client. +- **Scope fit:** The dispatcher only needs to distinguish three clients. A full NLP pipeline would be overkill. + +The trade-off is that prompts like `"compare codex and claude"` resolve to `codex` because `"codex"` is checked first. Users can always override with `--client`. + +### Sync-Only Initial Release + +The current implementation is entirely synchronous from the caller’s perspective: `executePrompt` returns a promise that resolves only when the child process exits or the timeout fires. + +**Rationale:** +- The primary use case is one-shot tasks (refactor, add tests, migrate) where the agent needs the complete output before proceeding. +- Streaming would require a different output contract (callbacks, generators, or an event emitter) and complicates the JSON error model. +- ACP already covers interactive, streaming, and session-based use cases. + +Streaming is an intentional future extension point (see below). + +### Error Taxonomy + +All runtime failures are represented as typed errors so callers and tests can branch precisely: + +| Error | When thrown | Data carried | +|---|---|---| +| `ClientNotFoundError` | Binary not on `PATH`, explicit `clientPath` missing, or `ENOENT` from `spawn` | `message` with client name | +| `ExecError` | Empty prompt, unknown client, timeout, non-`ENOENT` spawn error, or child exit | `message` + full `ExecResult` (`stdout`, `stderr`, `exitCode`) | + +`ExecError` carries the `ExecResult` so that timeout handlers still return partial output. This avoids losing buffered stdout/stderr when a long-running task is killed. + +### Injection-Friendly Module Boundaries + +Every non-trivial module accepts an `options` bag with injectable dependencies (`spawnSync`, `spawn`, `existsSync`, `whichSync`, `readFileSync`, etc.). + +**Rationale:** +- Unit tests can run without touching the real filesystem, `PATH`, or subprocess layer. +- The CLI itself injects its real dependencies through default parameters, so production behavior is unchanged. +- There is no global mocking required; each test provides its own narrow fakes. + +### Minimal Dependency Surface + +The runtime dependency graph contains exactly one external package: `minimist` (argument parsing). Everything else uses Node.js built-ins (`child_process`, `fs`, `os`, `path`). + +**Rationale:** +- Reduces supply-chain risk and install time. +- Avoids version-lock issues across Node.js 20+ environments. +- Keeps the compiled/bundled footprint negligible for a tool that is often installed as a sidecar. + +## Extension Points + +### Adding a New Client + +To support a fourth (or fifth) AI CLI client, change four files in `src/` and the corresponding tests: + +1. **`src/types.ts`** — Add the new name to the `ClientName` union type. +2. **`src/constants.ts`** — Append the new name to `CLIENT_NAMES`. +3. **`src/execute.ts`** — Add an entry to `CLIENT_ARGS` with the client’s native argument shape. +4. **`src/config.ts`** — No change required; the existing loop over `CLIENT_NAMES` automatically picks up the new env/flag/file keys. +5. **`src/dispatch.ts`** — Add a keyword check for the new client in `resolveClient`. Decide its precedence relative to existing keywords. +6. **Tests** — Add colocated test cases in `tests/dispatch.test.ts`, `tests/execute.test.ts`, and `tests/detect.test.ts`. + +No changes are needed in `cli.ts` because it iterates over `CLIENT_NAMES` for validation. + +### Streaming Support + +If a future use case requires real-time output (e.g., long-running codegen with progressive feedback), the cleanest extension is to add an optional `onData` callback to `ExecuteOptions`: + +```typescript +export interface ExecuteOptions { + clientPath?: string; + timeoutMs?: number; + spawn?: ...; + existsSync?: ...; + onData?: (chunk: string, stream: "stdout" | "stderr") => void; +} +``` + +When `onData` is provided, `executePrompt` would: +- Continue buffering internally for the final `ExecResult`. +- Also emit each chunk through `onData` so the caller can stream to a UI or logger. +- Reject/resolve with the same error taxonomy. + +This preserves backward compatibility: existing callers that omit `onData` receive the exact same buffered `ExecResult` they get today. + +### Platform Backends + +The current Windows support is limited to discovery (`where` instead of `which`, `.exe` extension assumptions). If future clients require platform-specific spawn options (e.g., PowerShell quoting rules), the extension point is `CLIENT_ARGS` or a new `CLIENT_SPAWN_OPTIONS` record keyed by `ClientName`. + +## Testing Strategy + +The test suite in `tests/` mirrors the `src/` structure: + +| Test file | Coverage | +|---|---| +| `cli.test.ts` | Argument parsing, command routing, JSON/text output modes, exit codes, error formatting | +| `config.test.ts` | Layered precedence of flags, env, file, and `which` fallback; malformed JSON tolerance | +| `detect.test.ts` | `which` success/failure, PATH directory fallback, version parsing, missing binary handling | +| `dispatch.test.ts` | Keyword matching, case insensitivity, `--client` precedence, `defaultClient` fallback, invalid flag handling | +| `execute.test.ts` | Successful execution, stderr capture, non-zero exit codes, `ENOENT` → `ClientNotFoundError`, timeout, empty prompt rejection, special-character preservation | + +All tests use injected mocks; no test spawns real client binaries or reads the real filesystem.