# Transcript: refactor `flagctl` for agent-friendly CI use

## 1. Task understanding

I was asked to rewrite a legacy Python `click`-based CLI (`flagctl`) so that
Claude Code agents running it in CI stop struggling with it, while keeping it
pleasant for humans. The explicit pain points in the prompt were:

- Agents hang on prompts.
- Output is hard to parse.
- No way to skip confirmations.

Hard constraints:

- Must remain a **single-file** `click`-based CLI.
- Must not break existing human usage.
- Input: `/Users/pedroproenca/Documents/Projects/dot-skills/skills/.experimental/cli-for-agents-workspace/evals/inputs/flagctl.py`
- Output file:
  `/Users/pedroproenca/Documents/Projects/dot-skills/skills/.experimental/cli-for-agents-workspace/iteration-1/eval-2-refactor-feature-flag-cli/without_skill/run-1/outputs/flagctl.py`
- Do NOT consult the `cli-for-agents` skill directory; produce the solution
  from my own defaults only. This is meant to be a baseline showing what an
  unguided agent produces.

## 2. Steps taken and why

### Step 1 — Read the legacy file
I read the original `flagctl.py` to understand the surface area and identify
every concrete cause of the reported pain. The file is ~95 lines and contains
four commands: `create`, `delete`, `list`, `toggle`, plus a thin
`api_request` helper.

### Step 2 — Enumerate the defects
From reading the source I catalogued the agent-hostile behaviours:

1. **Hanging on prompts.** `create` unconditionally calls raw `input()` for
   `description` and `owner`. Under CI (no TTY) `input()` blocks until EOF
   and, combined with the agent harness, looks like a hang.
2. **No way to skip confirmations.** `delete` and `toggle` always prompt
   `y/N` via `input()`. There is no `--yes` flag and no TTY detection.
3. **Hard-to-parse output.** `list` prints an ASCII box-drawing table with
   fixed column widths. `create`, `delete`, `toggle` print English sentences.
   There is no JSON or machine-readable mode.
4. **Errors go to stdout.** `api_request` does `print(f"error: {e}")` on any
   exception and calls `sys.exit(1)`. That both (a) pollutes stdout so agents
   can't safely pipe it, and (b) throws away the HTTP status so everything
   is exit code 1.
5. **No timeouts.** `urllib.request.urlopen(req)` has no `timeout=`, so a
   slow or hung server freezes CI indefinitely.
6. **Undifferentiated exit codes.** Everything is 0 or 1; an agent can't
   distinguish "not found" from "confirm required" from "network error".
7. **Vague error messages.** `error: <repr>` without context about which
   method/path failed or what the HTTP body said.
8. **Minor:** `list` shadows Python's builtin inside the module. Cosmetic but
   worth cleaning up by registering it under an internal function name.

### Step 3 — Design the fix
Design decisions I made, in priority order:

- **TTY detection is the single most important fix.** Every place that would
  have called `input()` now goes through either `require_value()` (for
  data) or `confirm_or_exit()` (for destructive confirmations). Both helpers
  check `sys.stdin.isatty()`. In a non-TTY they emit a structured error and
  exit with a distinct code instead of blocking.
- **`--json` is a global flag on the group**, not per-command, so you can
  `python flagctl.py --json <anything>` and get structured output
  uniformly. Storing it on `ctx.obj` keeps subcommands clean.
- **stdout vs stderr discipline.** Success payloads go to stdout; errors
  (human or JSON) go to stderr. That means `flagctl --json list | jq` is
  always safe.
- **Structured error envelope.** `{"ok": false, "error": {"code", "message",
  "details"}}`. The `code` is a stable machine key (`not_found`,
  `api_error`, `missing_input`, `confirmation_required`, `aborted`,
  `invalid_state`); `message` is human text; `details` carries extras like
  HTTP status.
- **Distinct exit codes.** I picked a small, documented set:
  `0 ok`, `1 generic`, `2 usage`, `3 confirmation required`, `4 not found`,
  `5 api error`. Documented in the module docstring so agents can read
  `--help` and figure it out.
- **Idempotent toggle.** Added `--to on|off` to `toggle` so agents can
  express "make sure this is on" without a read-modify-write race. Also
  added a no-op success path when current state already matches target.
- **Network timeout.** `DEFAULT_TIMEOUT_SECONDS = 15`, overridable via
  `--timeout` or `FLAGCTL_TIMEOUT`. Timeout errors become `api_error`
  with exit 5.
- **`ApiError` exception class.** `api_request` no longer exits directly;
  it raises a typed error. Commands catch it and call a single
  `handle_api_error` helper that maps HTTP status to the right exit code.
  This keeps HTTP plumbing separate from CLI UX.
- **`--api-base` override** via flag or `FLAGCTL_API_BASE` env var, since
  agents often need to point at a staging instance.
- **All `create` inputs are now flags** (`-d/--description`, `-o/--owner`,
  `--state`) so the command is fully non-interactive capable. In a TTY
  missing values still get prompted via `click.prompt`, preserving the
  human ergonomics from the original.
- **`list --state on|off|all`** filter. Cheap add, useful for agents.
- **`-h/--help` shortcut** and `--version` for the top-level group.

### Step 4 — Implement
I wrote the new `flagctl.py` in one pass using the `Write` tool. Key
structural choices inside the file:

- A clear "Output helpers / HTTP layer / Interaction helpers / CLI"
  section layout at the top of the file so the next reader sees the
  architecture immediately.
- `emit_success` / `emit_error` are the only two ways a command can
  speak to the user. That's what enforces the stdout/stderr discipline
  and the JSON mode uniformly.
- `require_value(ctx, value, flag_name, prompt_text)` is the single
  place where a missing CLI input becomes either a prompt (TTY) or a
  usage error (non-TTY). Commands just call it once per field.
- `confirm_or_exit(ctx, prompt, assume_yes)` is the single place
  destructive confirmation happens. Commands pass `assume_yes` from
  their `-y/--yes` flag.

### Step 5 — Verify
I ran four checks against the generated file:

1. `python3 -c "import ast; ast.parse(...)"` — syntax check, passed.
2. `python3 -m py_compile flagctl.py` — byte-compile, passed.
3. `python3 flagctl.py --help` — click loads the group and lists all
   four commands. Confirms decorators, group, and context all wire up.
4. Non-TTY regression tests:
   - `flagctl.py --json create </dev/null` → exits 2 with
     `{"ok": false, "error": {"code": "missing_input", ...}}`. No hang.
   - `flagctl.py --json delete my-flag </dev/null` → exits 3 with
     `{"ok": false, "error": {"code": "confirmation_required", ...}}`.
     No hang.

Both confirm the primary defect (CI hangs) is fixed and the error is
machine-parseable.

## 3. Tools used

- `Read` — to read the legacy `flagctl.py` input file once.
- `Bash` (`ls`) — to confirm the `outputs/` directory exists before writing.
- `Write` — to create `outputs/flagctl.py` and this transcript.
- `Bash` (`python3 -c "import ast..."`) — syntax check.
- `Bash` (`python3 -m py_compile`) — byte-compile check.
- `Bash` (`python3 flagctl.py --help`) — click structural check.
- `Bash` (non-TTY `create` / `delete` invocations with `</dev/null`) —
  behavioural check that the CLI exits fast in non-interactive contexts.

I deliberately did NOT use the `cli-for-agents` skill or any reference
material from under `skills/.experimental/cli-for-agents/`, per the task
constraint.

## 4. Issues encountered and resolutions

- **No real issues.** The main judgement call was whether to keep the
  global `API_BASE` patched by the group callback (simple, one-file CLI)
  or thread it through `ctx.obj` everywhere (cleaner but noisier). I
  went with patching the module global **and** also storing on
  `ctx.obj` so `api_request` stays easy to read while commands can
  still grab `timeout` from the context. Inside a single-file CLI this
  is an acceptable trade-off.
- I considered using `click.prompt(..., err=True)` for consistency, but
  default click prompts already go to stderr when reading, so no change
  was needed.
- I considered adding JSON Lines output for `list` but decided a single
  `{"ok": true, "flags": [...]}` object is more consistent with the
  rest of the JSON contract and easier to consume in one `jq` step.

## 5. Output produced

- **Rewritten CLI:**
  `/Users/pedroproenca/Documents/Projects/dot-skills/skills/.experimental/cli-for-agents-workspace/iteration-1/eval-2-refactor-feature-flag-cli/without_skill/run-1/outputs/flagctl.py`

  Highlights vs. the legacy file:
  - Global `--json`, `--api-base`, `--timeout`, `-h/--help`, `--version`.
  - `create` takes `NAME` + `-d/--description` + `-o/--owner` + `--state`;
    no more raw `input()`; missing values only prompt in a TTY.
  - `delete` has `-y/--yes`; non-TTY without `--yes` exits 3.
  - `list` accepts `--state on|off|all` filter; human output is a
    width-adaptive table; `--json` emits `{"ok": true, "flags": [...]}`.
  - `toggle` has `-y/--yes`, `--to on|off` (idempotent), and a no-op
    path when the current state already matches the target.
  - Typed `ApiError` with HTTP-status-aware mapping to exit codes
    (`4` for 404, `5` for everything else).
  - All network calls have a 15 s default timeout, overridable.
  - Errors always go to stderr; stdout is always clean JSON (in `--json`
    mode) or clean human text (otherwise).
  - Documented exit codes: `0 ok`, `1 generic`, `2 usage`, `3
    confirmation required`, `4 not found`, `5 api/network error`.

- **This transcript:**
  `/Users/pedroproenca/Documents/Projects/dot-skills/skills/.experimental/cli-for-agents-workspace/iteration-1/eval-2-refactor-feature-flag-cli/without_skill/run-1/transcript.md`
