git:20261016.a802ce4 to git:20261030.e0634b7

14 added, 1 removed. Audit A to A.

---

name: agent-task-splitter

description: Use when about to run two or more subagents, workflow lanes, or delegated CLI executors on one goal. Gives each lane a role, a pinned model tier, a disjoint file scope, a bounded brief, and a capped return, and fixes the merge and verification step before launch. Not for research-domain routing that owns .research, .paper, Zotero, Obsidian, or NotebookLM workflows; use research-hub-multi-ai for those.

---

# agent-task-splitter (fan-out planner)

Plan a fan-out before launching it. This skill plans; the host launches the

lanes. The name stays `agent-task-splitter` so existing prompts and plans keep

working.

## Pick the mode

| Mode | Use when | Artifacts |

|---|---|---|

| Native (default) | All lanes run inside one host session: parallel or background subagents, workflow lanes, one-shot CLI delegates, with the user present | Lane table in the conversation and one brief per lane. No `.coord/` plan, packets, or checkpoint. |

| Harness | A round spans sessions or tools, an unattended loop runs, work must resume after an interruption, a signed human gate is needed, or `AGENT_COLLAB_POLICY` is configured | `.coord/plan.yml` (schema v2) and `.ai/task_<NNN>_<slug>.md` packets; see [references/harness-plan.md](references/harness-plan.md) |

A configured policy always selects harness mode, and an unreadable configured

policy fails closed. Native mode follows the host's own limits and

permissions and adds no numeric limits of its own. Host mechanics are in

[native lanes](../../docs/native-lanes.md).

## Fan out only when

- two or more pieces are independent (none needs another's result) and each

has a checkable result; or

- implementation and independent review must be separate lanes.

Do not split exploratory debugging before the cause is known, a small

coherent change, or work where every lane needs the same context in tight

sequence. Doing it directly is the default.

## The lane table

Write it before launching anything:

|---|---|---|---|---|---|---|---|---|

| L1 | delegated-executor | subagent in a worktree | cheap | `src/a/**` | everything else | `pytest tests/a -q` | summary + paths | none |

| L2 | delegated-executor | CLI delegate | cheap | `docs/x.md` | `src/**` | link check passes | summary + paths | none |

| L3 | reviewer | read-only subagent | strong | nothing | `**/*` | verdict with evidence | verdict + findings | L1, L2 |

Rules:

1. Roles are `primary-agent`, `delegated-executor`, `reviewer`, and

`synthesizer`, defined in the

[public contract](../../docs/public-harness-contract.md). The executor

and model columns are host-adapter choices, not public plan fields.

2. The orchestrator assigns the model tier; a lane never picks its own.

Mechanical, pattern-following work goes to a cheap tier. Review, verdicts,

root-cause analysis, security, governance, and anything ambiguous go to a

strong tier.

3. Write scopes are disjoint. Two parallel writers never own the same file.

If scopes might touch, isolate the writers or run them in sequence.

4. Every lane has at least one runnable or objectively checkable acceptance

criterion.

5. Every lane has a capped return: a short summary plus file paths, never raw

logs or full diffs. `agent-context-budget` covers sizing.

6. A lane cannot approve its own output. Author and reviewer are different

lanes.

[references/task_splitter_heuristics.md](references/task_splitter_heuristics.md)

helps when a task could fit more than one role or DAG shape.

## Fix the merge step before launch

Write down, before any lane starts:

- who merges the results (normally the primary-agent) and in what order;

- the verification command run on the merged result, not only per lane;

- which `agent-acceptance-gate` presets the merged diff will trigger;

- commit boundaries: one reviewed commit per writing lane, or one commit

after the merged result passes. Read-only lanes need no commit.

## Brief per lane

# Lane <id>: <one bounded deliverable>

Repo/worktree: <absolute path>

Role: <role>. Model tier: <tier>.

Depends on: <lane ids and artifact paths>

Before editing, list the exact paths you may write and must not touch.

Stop and report if they conflict with this brief.

May read: <paths>

May write: <paths>

Must not touch: <paths>

External actions: none unless named here.

Edits required: yes | unchanged output allowed because <reason>

+ Goal this lane serves: <the outcome of the whole job, one line>

+ Already decided (do not reopen): <decisions, copied word for word>

Acceptance: <runnable check>

- Return (capped): status; short summary; files changed; checks run and

+ Return (capped): status; short summary; files changed; the acceptance

+ command and the last lines of its actual output; other checks run and

results; risks; blockers. Put long output in a file and return its path.

+ If the job already has a plan header (for example from the `aim-higher`

+ skill), copy its outcome, outside check, not-doing and already-decided lines

+ into these fields instead of rewriting them. Without one, fill the fields

+ yourself.

## Drift guards

- Copy identifiers (slugs, paths, field names, version strings) verbatim into

the brief. Do not paraphrase them.

- Record the pre-lane baseline (commit or file hashes) so the result can be

attributed. File times and a process exit status do not prove the work was

done; use the [task-content evidence review](../../docs/task-content-evidence.md).

- State whether edits are required. A lane that reports success without

changing its required files has failed unless the brief allowed unchanged

output.

+ - Check each return against its brief when it arrives, not only at the end: a

+ "done" without the acceptance command's actual output stays unverified, and

+ a result that departs from the brief's steps or decided items is drift even

+ when its own checks pass.

- Missing, null, failed, declined, cancelled, and timed-out lanes stay

non-success. Filter them out of synthesis but keep their records.

- Agent agreement never replaces running the checks.

## Harness mode

1. Write `.coord/plan.yml` (schema_version 2) and one packet per non-inline

task, using [references/harness-plan.md](references/harness-plan.md).

2. Immediately before each spawn the host runs

`agent-collab policy evaluate --policy <policy_ref> --checkpoint <checkpoint_ref> --json`

and spawns only on `decision=continue` with `spawn_allowed=true`. The plan

never overrides that decision.

3. Coordination files are scratch and gitignored. Promote only an explicit

checkpoint snapshot, shipping artifact, or acceptance record.

4. Do not encode retries in the plan; the policy decides them.

Historical schema-less plans and provider-specific task paths are parse-only;

see [migration 0.4](../../docs/migration-0.4.md).

## Output

Return the lane table, each brief (or its path), the ready lanes in launch

order, and the merge-and-verify step. Do not launch lanes from this skill and

do not turn a planning-only request into implementation.