flatten-workflow-parallel-arrays-before-collecting SKILL.md skillA
flatten-workflow-parallel-arrays-before-collecting from wan-huiyan/agent-traffic-control is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add wan-huiyan/agent-traffic-control/flatten-workflow-parallel-arrays-before-collecting@v1.0.0Pins v1.0.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- wan-huiyan/agent-traffic-control
- Path
plugins/agent-traffic-control/skills/flatten-workflow-parallel-arrays-before-collecting/SKILL.md- Versions recorded
- 1
- Latest version
- v1.0.0, committed Aug 12, 2026
- Size
- 4,979 bytes
- Repository stars
- 3
- License
- MIT
Claude Code Workflow tool gotcha: a pipeline() stage that returns parallel([...]) resolves to a BARE ARRAY, but a sibling stage that returns {dimension, verified: []} resolves to an OBJECT — so a collector written as `per.flatMap(p => Array.isArray(p?.verified) ? p.verified : [])` SILENTLY DROPS every item from the array-shaped stages. Use when: (1) a fan-out review/verify workflow reports "0 confirmed / 0 refuted" or "0 findings" but the agent count / journal shows verify agents actually ran…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Workflow pipeline(): a stage returning parallel() is a bare array the collector silently drops
## Problem
In the Claude Code **Workflow** tool, `pipeline(items, stage1, stage2, …)` runs each item
through the stages. A common fan-out-then-verify shape makes stage-2 return **different
shapes per item**:
```js
const per = await pipeline(DIMENSIONS,
d => agent(findPrompt, {schema: FINDINGS}), // stage 1
(findings, d) => {
if (!findings.confirmed.length)
return { dimension: d.key, verified: [] }; // OBJECT shape (no findings)
return parallel(findings.confirmed.map(f => () => // BARE ARRAY shape (has findings)
agent(verifyPrompt(f), {schema: VERDICT}).then(v => ({...f, verdict: v}))));
});
```
`per[i]` is now an **object `{verified: […]}`** for dimensions that found nothing, but a
**bare array `[{…verdict…}, …]`** for dimensions that DID find candidates (because
`parallel()` resolves to an array). A collector written for only the object shape:
```js
const all = per.flatMap(p => Array.isArray(p?.verified) ? p.verified : []); // BUG
```
evaluates `Array.isArray(undefined)` → false for every array-shaped element → returns `[]`
…Read the whole file at its exact version.
How to install
mdr add wan-huiyan/agent-traffic-control/flatten-workflow-parallel-arrays-before-collecting@sha256:cebd7d83c252bc2cThe line at the top of this page pins the label v1.0.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_ipqdjwjbvunuotxt)
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Versions
The registry has recorded 1 version of this file, committed on Aug 12, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4979 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
wan-huiyan/agent-traffic-control · 3 stars · license MIT · pushed 2026-09-22 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ipqdjwjbvunuotxt GET https://markdownregistry.com/api/v1/resolve?ref=wan-huiyan/agent-traffic-control/flatten-workflow-parallel-arrays-before-collecting GET https://markdownregistry.com/api/v1/blob/cebd7d83c252bc2c345df16704d4f103582b90490397ccb56339d7fc0e8e4a8c
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