/write-flow

name: write-flow
description: MUST use when creating flows.

Windmill Flow CLI Guide

Creating a Flow

**You — the AI agent — scaffold the flow yourself by running `wmill flow new <path>` with the right flags. Do NOT hand-create the folder + `flow.yaml`, and do NOT tell the user to "run `wmill flow new` and follow the prompts".**

`wmill flow new` creates the folder with the correct suffix (`__flow` or `.flow` depending on the workspace's `nonDottedPaths` setting), writes a minimal `flow.yaml` shell, and prints Claude-specific next-step hints. Scaffolding by hand skips all of that and often picks the wrong suffix.

Step 1 — Gather path + summary by asking the user

You need two things:

1. **path** — the windmill path, e.g. `f/folder/my_flow` or `u/username/my_flow`. 2. **summary** — a short description of the flow.

If the user's request didn't supply both, ask for both in a single round-trip. Use whichever interactive question facility your runtime provides — a structured multi-choice tool if available, otherwise plain chat — and provide one or two example values for each (with an "Other" / free-form fallback). Do not guess paths or summaries.

Step 2 — Run the command yourself

wmill flow new f/folder/my_flow --summary "Short description"

Add `--description "..."` when the user provided a longer explanation worth preserving separately from the summary.

Step 3 — Fill in `flow.yaml`

Open the generated `flow.yaml` (under the folder the command just created) and replace the empty `value.modules` + `schema` with the real flow definition.

For rawscript modules, use `!inline path/to/script.ts` for the content key. Inline script files should NOT include `.inline_script.` in their names (e.g. use `a.ts`, not `a.inline_script.ts`).

Once the flow has real content, **offer** to open the visual preview as a one-sentence next step (e.g. "Want me to open the visual preview?"). Don't auto-open — opening the dev page has side effects (browser window, possibly a `launch.json` entry) and the user should consent.

Anti-patterns to avoid

• ❌ Hand-creating the `__flow` folder + `flow.yaml` instead of running `wmill flow new`. You'll miss the suffix-setting resolution, the default shape, and the Claude hints.
• ❌ Telling the user to "run `wmill flow new <path>`" — you can and should run it yourself.
• ❌ Inventing a path/summary instead of asking the user.

CLI Commands — running, previewing, deploying

After writing, act on the user's intent instead of just listing commands. Run `wmill flow preview` yourself when it fits (see "After writing — offer to run, don't wait passively" below). `wmill generate-metadata` regenerates local lock/hash files (not a deploy) but re-resolves deps — offer it and run on agreement, unless the project's `AGENTS.md` opts into running metadata automatically. Only *name* `wmill sync push` (the deploy) so the user can approve it. The options:

• `wmill flow preview <flow_path>` — **default when iterating on a local flow.** Runs the local `flow.yaml` against local inline scripts without deploying. Add `--remote` to use deployed workspace scripts for PathScript steps instead of local files. Add `--step <step_id>` to run only one module in isolation (see "Single-step vs whole-flow preview" below).
• `wmill flow run <path>` — runs the flow **already deployed** in the workspace. Use only when the user explicitly wants to test the deployed version, not local edits.
• `wmill generate-metadata` — regenerate stale local `.lock` files for the flow and its inline scripts and refresh their content hashes in `wmill-lock.yaml`. Writes local files only (not a deploy). Run it after editing inline scripts whose imports or arguments changed, so `wmill-lock.yaml` doesn't drift and add noise to git-sync/CI. By default it scans **scripts, flows, and apps** across the workspace but only regenerates stale ones; pass the flow's folder as an argument (or run from that subdirectory) to limit the scope to the flow you edited. Note a flow (or script) that imports a changed shared script is pulled in too — run `wmill generate-metadata --dry-run` to see exactly what is stale and why (`content changed` vs `depends on <path>`) before applying.
• Deploy local changes to the workspace — via `git push` or `wmill sync push` depending on how the repo is wired (see the **Deploying** section in `AGENTS.wmill.md`). Only suggest/run a deploy when the user explicitly asks to deploy/publish/push — not when they say "run", "try", or "test".

Preview vs run — choose by intent, not habit

If the user says "run the flow", "try it", "test it", "does it work" while there are **local edits to a `flow.yaml`**, use `flow preview`. Do NOT push the flow to then `flow run` it — pushing is a deploy, and deploying just to test overwrites the workspace version with untested changes.

Only use `flow run` when:

• The user explicitly says "run the deployed version" / "run what's on the server".
• There is no local `flow.yaml` being edited (you're just invoking an existing flow).

Only use `sync push` when:

• The user explicitly asks to deploy, publish, push, or ship.
• The preview has already validated the change and the user wants it in the workspace.

Single-step vs whole-flow preview

Use `flow preview <flow_path> --step <step_id>` when the user is iterating on one module and the flow's upstream steps aren't part of what they're trying to validate. It runs only that step's runnable (rawscript: the inline script; script: the PathScript, locally if available; flow: the subflow by path) and is much faster than running the whole flow when previous steps are slow or expensive. The step id is resolved by walking nested branchone/branchall/forloopflow/whileloopflow modules and includes the special `preprocessor` and `failure` modules.

Use `flow preview <flow_path>` (no `--step`) when steps depend on each other's outputs, when the user is validating the overall control flow, or when `--st