Use when an agent needs to author a standalone Dynamic Workflow at runtime: write a Starlark program (loops, conditionals, data-driven fan-out) that calls agent()/parallel()/phase()/log() over the harness runtime, declare a mandatory workflow(name, design_intent) header, run it with `harness workflow run-script`, and read the resulting WorkflowRun/WorkflowStep records back from the dashboard snapshot or store.
Installation
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Use when an agent needs to author a standalone Dynamic Workflow at runtime: write a Starlark program (loops, conditionals, data-driven fan-out) that calls agent()/parallel()/phase()/log() over the harness runtime, declare a mandatory workflow(name, design_intent) header, run it with `harness workflow run-script`, and read the resulting WorkflowRun/WorkflowStep records back from the dashboard snapshot or store.
Author Workflow
Use this skill to make a shell-capable agent (Codex, Claude Code, or any other)
author a workflow at runtime and run it through the harness, with no MCP or
plugin. Starlark is the SOLE dynamic authoring surface: write a .star program
and run it through harness workflow run-script, which journals a WorkflowRun
plus one WorkflowStep per agent leaf.
write a .star program -> harness workflow run-script <prog.star> -> read the run back
The runtime is provider-agnostic (crates/harness-workflow). Each agent() call
names a PROVIDER ("codex", "claude", or "kimi"); the CLI spins up a NEW
one-shot ephemeral worker for that call (it does NOT deliver to a pre-existing
member) and journals a WorkflowRun plus one WorkflowStep per agent call —
identical to the built-in workflow run --name path, so the run shows up live on
the Agent Dashboard Workflows surface.
Each ephemeral worker is READ-ONLY by default and runs in the selected project
root — even on a provider (like kimi) that cannot physically enforce read-only,
provider capability gaps do not silently create worktrees (#190). A worker may
edit only when the call sets writable=True; standalone run-script then uses a
throwaway worktree and saves the diff as a pending WorkflowPatch, so the live
repo is not changed until the patch is applied. A read-only call can still opt
into isolation="worktree" when it explicitly needs an isolated checkout.
write_mode="direct" is the explicit exception for a simple serial leaf that
should edit the selected project root immediately.
When To Use
The shape of the orchestration is decided at runtime, not baked into a built-in
registry workflow.
You want to fan work out (scan, then parallel fix; map/reduce; a data-driven
fan-out whose width depends on a prior step) and have the run recorded as
evidence.
A Lead Agent wants a worker to both design and execute a small multi-agent plan.
Do not use this skill to do the domain work yourself. Use it to author the
program, run it, and then read the recorded run.
Product Boundary
Dynamic Workflow is a standalone executor. Its Starlark program owns internal
steps, fan-out, retries, structured output, and patch decisions. A host may
attach the completed WorkflowRun, its artifacts, and its result to an outer
Mission/Wave gate, but the workflow does not create or require a dependency graph,
agent-team assignment, or compatibility lifecycle record.
Do not reconstruct a workflow as a second plan after it runs. Treat the
program, its WorkflowRun, WorkflowStep records, artifacts, and final
verdict()/output() as the executor's durable truth.
Choose The Write Scenario
Pick the landing mode before writing the program. Most bugs in workflow authoring
come from mixing permission (writable=True) with landing semantics.
Scenario
Use
Do not use
Read-only scan / review / synthesis
Omit writable; use schema= for any branch decision.
Do not assume a read-only leaf can run arbitrary shell on every provider; Kimi cannot physically enforce read-only, so choose codex/claude when hard read-only enforcement matters (read-only leaves still run on the project root regardless — #190).
Failure-aware retry / fallback
Use return_status=True and inspect ok, reason, detail, and structured before retrying or aborting.
Do not parse prose to guess whether a leaf timed out, failed, or merely returned a negative domain verdict.
Normal code implementation
writable=True, default worktree landing, owned_paths=[...], leave persist_changes unset or "patch". Operator or workflow later applies/rejects the pending WorkflowPatch.
Do not rely on expected_artifacts to preserve code edits; it is for named files, not source diffs.
Workflow-internal apply/reject
Implement in one writable leaf, have that leaf return a compact diff/gate summary, review it with a schema'd read-only gate, then call apply_patch(label, reason) or reject_patch(label, reason).
Do not auto-apply without a gate; if the reviewer cannot see the relevant evidence, leave the patch pending for manual review.
Simple direct edit
One serial agent(..., writable=True, write_mode="direct") against a clean git project. Use for small docs/config edits the operator intends to land in the current tree now.
Do not use direct mode inside parallel() / pipeline(), and do not split direct edit/repair across multiple writable leaves: after the first leaf dirties the repo, another direct leaf is refused.
Parallel fixes
parallel([{..., "writable": True, "owned_paths": [...]}, ...]); each slot gets its own worktree and patch. Use unique labels such as fix:1, fix:2.
Never use write_mode="direct" for concurrent mutations. Avoid duplicate labels if humans must apply/reject individual patches.
File/artifact generation
writable=True, expected_artifacts=[...], and artifact_manifest([...], artifact_root=..., write_roots=[...]).
Do not write artifacts to absolute paths or outside declared roots; those writes escape worktree cleanup/accounting.
Code should be reviewed before landing in the selected repo.
pending-manual-review.star
Dedicated pending path: create a patch, make no internal apply/reject call, output operator commands.
Evidence is insufficient for an automated decision but the workflow should complete.
build-and-gate.star
One writable worker owns edit/test/repair inside its worktree; Starlark gates the worker report.
The edit and gate must share one temporary checkout.
artifact-manifest.star
Generated file copy-back plus durable artifact manifest tracking.
The important output is a file/report/asset, not only a source diff.
scan-then-parallel-fix.star
Runtime-determined fan-out into multiple isolated writable patches.
A scan decides how many independent fixes should run concurrently.
The Mandatory workflow(name, design_intent) Header
Every program MUST call workflow(name, design_intent) exactly once, before the
rest of the body. It declares:
name — the workflow name (becomes WorkflowRun.workflow_name; overrides the
CLI --name / file-stem default).
design_intent — a free-text explanation of WHY the workflow is structured the
way it is. This is the run's durable rationale.
The run is REJECTED fail-fast if workflow(...) is never called, or the
design_intent is blank or shorter than ~20 characters:
every workflow must declare a design_intent explaining WHY it is structured this way
The captured design_intent is persisted on WorkflowRun.design_intent, and the
raw program text is snapshotted under WorkflowRun.spec = {"lang":"starlark","script": <text>}
for reproducibility.
Host API
The interpreter is Starlark
(crates/harness-workflow/src/starlark_front.rs),
the same dialect Bazel uses. It is HERMETIC by design: the script has no clock, no
randomness, and no IO. The orchestration (which agents run, in what order, with what
prompts) is therefore deterministic — the ONLY nondeterminism lives in the journaled
agent() leaves.
Identifiers must be ASCII (a Starlark/Python-2 rule): a non-ASCII variable name
like 要点 = agent(...) fails to PARSE (invalid input 要). Non-ASCII text is fully
supported everywhere it belongs — inside string LITERALS: prompts, label=, the
workflow(name, design_intent) strings, and of course the agents' output. So write a
fully Chinese workflow freely; just keep variable names ASCII (scan = agent("用中文…"),
not 扫描 = agent(...)).
A program calls these globals (no import; they are pre-bound):
REQUIRED header. Declares the run name + the WHY behind its shape. Optional budget_usd=N caps the run's cumulative spend; success_criterion="..." declares the bar verdict() is judged against. Must run once before the body.
Run ONE ephemeral worker synchronously. prompt is positional; the rest are keyword args. model= overrides the provider default model; effort= overrides reasoning effort; service_tier= overrides the Codex CLI service tier; fallback_model= sets a provider fallback when supported; timeout_s= is a per-leaf wall-clock cap; expected_artifacts= validates output files; persist_changes="discard" opts out of patch capture; write_mode="direct" edits the selected repo for a serial writable leaf; owned_paths= guards patch apply. READ-ONLY by default; writable=True permits edits and normally uses a throwaway worktree. With schema={...} it returns a parsed dict. schema_strict=True rejects candidates whose top-level string fields are all empty and requires schema=. With return_status=True, it returns an inspectable status dict.
parallel([dict, ...])
list (input order)
Barrier fan-out. Specs may set the same leaf options as agent(), including schema_strict; write_mode="direct" is rejected for concurrent edits.
pipeline(items, stages)
list (one per item)
No-barrier streaming. Stage specs may set the same leaf options as agent(), including schema_strict; write_mode="direct" is rejected here.
Declare a workflow-internal decision over a captured patch. The CLI applies or rejects the durable WorkflowPatch after the standalone run-script journals it, with the same guards as manual workflow patch apply/reject.
Declare durable artifact files to validate into WorkflowArtifactManifest rows with exists/size/hash/status.
verdict(ok, reason="")
—
Declare the run's TYPED outcome. reason may be positional or keyword (verdict(ok, "why") ≡ verdict(ok, reason="why")). ok=False finalizes the run Failed even if every worker ran — so "workers ran" ≠ "intent satisfied". A closed-loop program's final gate calls this.
output(value)
—
Declare the run's RESULT — the one unambiguous answer the calling agent reads back. value (a string or dict) is persisted verbatim under final_output.result, UNCAPPED, so the caller reads one field instead of digging the answer out of a step by label. Last call wins; pass a schema'd dict when you want the answer typed (a free-text agent() return is the worker's FULL reply — not truncated).
json.encode(value) / json.decode(str)
string / value
Serialize a prior agent()'s dict to inject it verbatim into the next prompt (forward-injection), or parse JSON back.
phase(name)
—
Set the default phase for the steps that follow.
log(message)
—
Emit a progress line (persisted in the run's final_output.logs).
args
value
The --args JSON, injected as a module global (e.g. args["items"]).
Rules every call obeys:
provider is "codex", "claude", or "kimi" — the provider whose ephemeral
worker runs the leaf. There is NO member binding; the provider drives delivery.
"kimi" (Kimi Code) is registry-routed like the others, but its headless kimi -p
surface is leaner: no native schema / effort / service-tier / budget flags and
a flat reply stream, so schema= degrades to text-extraction and effort=,
service_tier=, token, and cost come back empty. Kimi also does not physically
enforce a read-only sandbox, but read-only Kimi leaves still run in the selected
project root rather than forcing a worktree. Use codex or claude when hard
read-only enforcement matters; keep schema-gated control-flow leaves on codex
or claude.
prompt, label, and phase are non-empty strings; optional model (any
non-empty string) overrides the provider's default model — route a CHEAP model
to read-only verify/review steps and the strong model to the builder. The value
is passed VERBATIM to the provider CLI and is NOT validated by the harness (an
unknown name is rejected by the provider), and the supported set is NOT
hardcoded — it changes as each provider ships new models. Don't rely on a
baked-in list; discover the current models from the provider's own CLI:
codex — codex --help (the -m/--model flag) plus ~/.codex/config.toml
(model, [profiles.*], [model_providers.*]) for what's configured.
claude — claude --help; --model takes a latest-model ALIAS
(e.g. sonnet / opus / haiku) or a full model id.
kimi — kimi provider list (configured providers, model aliases, and the
default) and kimi provider catalog to discover/import more.
effort overrides the worker's reasoning effort, passed through verbatim to the
provider — codex accepts minimal|low|medium|high (mapped to -c model_reasoning_effort=…), claude accepts low|medium|high|xhigh|max (mapped to
--effort …). Use a low effort on cheap mechanical leaves and a high effort on the
hard reasoning step. Not validated by the runtime — the provider CLI rejects a
value it does not know, so use each provider's own levels.
service_tier overrides Codex's speed/cost tier for this leaf, passed through
verbatim as -c service_tier=<value> (for example default, priority, or
flex, depending on the installed Codex CLI). Leave it unset to inherit
~/.codex/config.toml; claude and kimi ignore it.
image is a list of image file paths attached to the worker. Codex receives
repeatable -i <file> args; claude -p has no image flag, so the paths are
injected into the prompt for the worker to open with the Read tool.
add_dir is a list of extra directory paths the worker may access. Codex and
claude both receive repeatable --add-dir <path> args.
expected_artifacts is a list of repo-relative files the step must produce;
the runtime rejects absolute paths and .. components.
persist_changes controls writable diffs: the default saves non-empty diffs as
pending WorkflowPatch rows; set persist_changes="discard" only when the diff
is intentionally throwaway. Use owned_paths=["src", "docs"] on code-writing
leaves so patch apply can reject path escapes. Patch capture only happens for a
step that both SUCCEEDED (ok) and was declared writable=True — a failed
leaf's diff is discarded, and a read-only leaf never produces a patch (the
writable gate, not isolation, is the guarantee; read-only leaves run on the
project root even on a provider that can't enforce read-only — #190; see
Workspace: read-only by default).
Starlark validation
rejects auto_apply_on_verdict=True or persist_changes="patch" on a
writable=False leaf, and rejects any persist_changes other than
"patch"/"discard" or write_mode other than "direct"/absent, in
agent(), parallel(), and pipeline() specs alike.
write_mode="direct" is the explicit escape hatch for a simple SERIAL edit that
should modify the selected project root immediately. It requires
writable=True, a git-backed clean repo, and cannot be used in parallel() /
pipeline() specs. It records direct_diff evidence and does NOT create a
pending WorkflowPatch because the change is already in the working tree.
artifact_root and write_roots are metadata for artifact manifests. Use
artifact_manifest([...], artifact_root="out", write_roots=["out"]) when a
workflow produces files that should be visible and validated after completion.
return_status=True changes the script-visible return into a dict with ok,
reason, detail, text, structured, provider_session_id, label,
phase, provider, isolation, and ordinal. Use it when the workflow needs
to branch on timeout/failure categories or retry/abort deliberately instead of
guessing from prose.
fallback_model is an optional fallback model override. Claude receives
--fallback-model <model>; codex has no fallback-model flag, so it is not
passed to codex.
The only supported isolation value is "worktree".
Reference args inside a prompt with + concatenation ("audit " + args["area"])
for short one-liners, or .format() into a triple-quoted string for longer /
multi-line prompts — see Writing prompt text.
Writing prompt text: triple-quote long prompts
+ concatenation is fine for a short one-liner, but a long or multi-line prompt
(a role brief, a numbered deliverable list, a report contract) is far more
readable as a triple-quoted string — standard Starlark, enabled here, and it
preserves newlines verbatim:
res = agent(
"""You are a payments auditor. Audit {area}.
Look for, in order:
- missing idempotency keys on writes
- unhandled refund / chargeback races
- money paths that skip the ledger
Return a numbered list, one concrete finding per line as `file:line — issue`.""".format(area=args["area"]),
schema={"items": "the findings, one per line"},
label="audit",
)
.format(name=value) injects args (a clean alternative to `"… " + args["area"]
" …"); '''…'''is the single-quote form. **The one gotcha: a triple-quoted string keeps every character between the quotes, including leading indentation.** So write the body flush-left even when the assignment is indented inside adef, if`, or comprehension — otherwise the indentation leaks into the prompt:
defbuild_prompt(task):
# WRONG — every line after the first carries 8 leading spaces into the promptreturn"""Implement {task}.
Keep tests green.""".format(task=task)
# RIGHT — body flush-left; only the first line sits on the return statementreturn"""Implement {task}.
Keep tests green.""".format(task=task)
(A stray leading newline from opening """ on its own line is usually harmless —
strip it with .strip() / .lstrip("\n") if a worker is whitespace-sensitive.)
Starlark does NOT auto-join adjacent string literals. Python concatenates
"a" "b" into "ab"; Starlark rejects it as a parse error (unexpected string literal … expected one of "+", …). So to break a long single-line string across
source lines you must use explicit + or a triple-quoted block — never bare
adjacent strings:
# WRONG — parse error in Starlark (this is a Python-only convenience)
workflow("x", "first part ""second part")
# RIGHT — explicit + , or a triple-quoted string
workflow("x", "first part " +
"second part")
Workspace: read-only by default, writable=True to edit
Every call is READ-ONLY by default and runs in the selected project root — the
worker may read files and run searches but must not edit files or run shell. This
is the safe default for the common case (finders, reviewers, verifiers,
synthesizers all only read). The runtime does not create a worktree merely
because the provider cannot physically enforce read-only; choose codex/claude for
hard read-only enforcement.
A call that must EDIT files or run commands sets writable=True. That worker is
automatically run in its own harness-owned throwaway git worktree under
.harness/worktrees/ (writes land in a discardable checkout, NOT the live repo);
its git diff becomes the step's evidence, and the worktree is cleaned up after
(auto-removed if unchanged, never auto-merged directly). A non-empty writable diff
is saved as a pending WorkflowPatch unless the step sets
persist_changes="discard". So a parallel() block of several writable slots is
automatically conflict-free — each gets its own worktree and its own patch.
For a deliberately simple serial edit, use direct mode:
agent(
"Make the requested one-file docs edit. Do not touch unrelated files.",
label="direct-doc-edit",
writable=True,
write_mode="direct",
)
Direct mode separates permission from landing: writable=True gives the
provider edit/shell permission; write_mode="direct" says those edits land in
the selected project root immediately. The runtime refuses direct mode if the repo
is dirty before the step, if the project is non-git, or if the spec is inside
parallel() / pipeline(). Use it for small operator-intended edits where
normal git status/review is enough. Use the default worktree+patch path for code
changes, parallel edits, uncertain prompts, or anything that needs review before
landing.
When a writable leaf PRODUCES FILES that must survive cleanup, declare
expected_artifacts=["repo/relative/path.ext", ...]. At step end the CLI copies
each declared non-empty file from the throwaway worktree into the live repo before
cleanup; a missing, empty, absolute, or .. path marks that step FAILED. An empty
list preserves legacy behavior. Use this for file-producing leaves such as image
generation: it both asserts the output exists and persists it past the ephemeral
worktree.
For code-writing leaves, prefer this shape:
IMPLEMENT = {
"gate_green": "bool",
"summary": "what changed and why",
"files_changed": "repo-relative files changed, one per line",
"diff_review_notes": "compact diff/gate notes for the reviewer",
}
impl = agent(
"Implement the focused change and do not touch unrelated files. Before " +
"reporting, run the relevant gate and include compact diff/gate notes.",
label="implement",
writable=True,
persist_changes="patch",
owned_paths=["src", "tests"],
schema=IMPLEMENT,
)
review = agent(
"Review whether this implementation should be applied, rejected, or left " +
"pending because evidence is insufficient:\n" + json.encode(impl),
label="review",
schema={
"action": "one of: apply | reject | pending",
"reason": "why this action is correct",
},
)
action = review["action"] iftype(review) == "dict"else"pending"
reason = review["reason"] iftype(review) == "dict"else"review did not return JSON"if action == "apply":
apply_patch("implement", review["reason"])
elif action == "reject":
reject_patch("implement", reason)
else:
action = "pending"# action == "pending": make no patch call; the operator applies/rejects later.
Manual operator path: harness workflow patch list, harness workflow patch show <run_id> --step implement, then harness workflow patch apply <run_id> --step implement or harness workflow patch reject <run_id> --step implement. Without
--allow-dirty, apply refuses only when a path THIS patch touches already has
local modifications (or a to-be-created file already exists untracked) —
unrelated dirty/untracked files elsewhere in the repo no longer block it.
If the workflow-internal reviewer cannot see enough real evidence in the worker's
structured report, do not call apply_patch(); leave the patch pending for manual
inspection with workflow patch show.
A writable worker runs with FULL permissions — codex --sandbox danger-full-access, claude --permission-mode bypassPermissions — so it can run
arbitrary shell, git add/git commit, install deps, and reach the network.
(Codex's workspace-write was deliberately NOT used: it blocks writes to .git/,
so commits failed with "sandbox denied .git".) The throwaway worktree — not an OS
sandbox — is the boundary: a writable prompt executes for real, so scope it, and
never point a workflow with destructive/money-moving writable steps at a tree you
care about.
Nested harness commands from an ephemeral leaf are store-isolated by default. The
runtime injects a session-local child store/home for harness ... commands run
inside a provider leaf, so a worker cannot accidentally create tasks, evidence,
proposals, or decisions in the parent project's central store. If a workflow
intentionally needs a leaf to mutate the canonical harness store, invoke
run-script with HARNESS_WORKFLOW_ALLOW_STORE_MUTATION=1 and record that grant
in the task/evidence; otherwise keep store writes in the Lead process after the
workflow returns.
isolation="worktree" is the explicit form of the same thing (a read-only call
that still wants an isolated checkout); writable=True implies it. Do not set it
for ordinary read-only reviews or scans.
The workflow's cwd must be a git repo for writable / isolation="worktree"
steps — the throwaway worktree is created with git worktree add. In a non-git
directory such a step fails fast with an actionable error. Either run the workflow
from a git repo (git init), or keep the step READ-ONLY and retrieve its produced
text with harness workflow get-output <run_id> --step <label>. Under a
project-switching serve, the worktree base / worker cwd is the run's selected
project root (#147), not necessarily where the binary launched.
A writable / isolated leaf branches from the PROJECT-ROOT checkout's current
HEAD, not the cwd that launched run-script. The CLI prints the worktree base
(root + branch + short HEAD) when it creates one; keep the selected project root
on the intended branch or a writable leaf can branch from a stale base.
Standalone run-script still discards the temporary worktree, but not the diff:
the patch is durable in the store. Apply or reject it explicitly, or have the
workflow declare apply_patch() / reject_patch() after a review leaf.
Structured Output: the foundation
A worker called WITHOUT schema returns free text — and you cannot reliably
branch on free text. Pass schema={...} and the worker is forced to reply with a
single JSON object carrying the schema's TOP-LEVEL KEYS, parsed back into a native
Starlark dict:
res = agent(
"Audit " + args["area"] + " and report whether it is safe to ship.",
schema={"ok": "bool", "findings": "findings, one per line"},
)
# res is a real dict with native scalar types: res["ok"] is a bool.if res == None:
log("worker produced no valid JSON — skipping")
elif res["ok"]:
log("clean")
else:
raw = res["findings"] iftype(res["findings"]) == "string"else""for f in [x.strip() for x in raw.splitlines() if x.strip()]:
log("finding: " + f)
The schema's KEYS are the contract; the VALUES ("bool", "list of strings")
are shape hints handed to the worker. The runtime appends a JSON-only
instruction, and if the first reply is not a valid JSON object with those keys it
re-runs the worker ONCE with a corrective nudge. If it STILL fails, the call
returns None (and the step is journaled as a schema failure). Always handle
None.
This is what makes verify / judge / synthesis reliable: a verifier that returns
{"ok": bool} is something you can branch on; a verifier that returns a paragraph
is something you have to guess at. Reach for schema on every leaf whose output
controls the workflow's CONTROL FLOW.
parallel() honours schema per-spec: a spec with a schema that parsed yields a
dict in the result list, an unschema'd (or unparsed) spec yields its summary
string — so guard with type(x) == "dict" when a fan-out mixes them.
Field types — known type words COERCE; other hints stay strings. In the flat
{"key": "hint"} form a hint that is a recognised scalar type word — "bool",
"int"/"integer", "number"/"float" — is enforced as that REAL JSON type, so
{"ok": "bool"} gives you a real True/False and {"n": "int"} a real integer
(branch directly: if res["ok"]:, no string compare). Any OTHER hint (e.g.
"the file path", "list of strings") stays a STRING — the hint just guides the
worker and the runtime enforces the key is present. To get a LIST out of a leaf,
have it return items ONE PER LINE and .splitlines() the string field — the
robust, dry-run-safe idiom the examples use (for x in res["items"].splitlines()).
For hard array/enum/nested enforcement on a live run, pass a full JSON Schema dict
({"type": "object", "properties": {...}, "required": [...]}) — it is enforced
natively, but --dry-run's mock only fills the flat form, so prefer the
one-per-line idiom in examples that must run under --dry-run.
Default to pipeline() over parallel()
parallel() is a BARRIER — it blocks until every spec finishes. pipeline() is
NOT: each item flows through all stages independently, so item A can be at stage 3
while item B is still at stage 1. When you have multi-stage PER-ITEM work (find →
verify each finding; assess → refute each dimension), reach for pipeline() first
— the wall-clock is the slowest single CHAIN, not the slowest stage summed over a
barrier. (See examples/assess-verify-synthesize.star.)
Smell test: if you wrote a = parallel(...), then a middle transform(a) that is
just a flatten / map / filter with NO cross-item dependency, then another
parallel(...), you did not need that barrier — fold the transform into a
pipeline stage. A barrier is only correct when stage N genuinely needs ALL of
stage N-1 at once: a dedup/merge across the whole set, an early-exit on the total
count, or a judge that compares the items to each other.
The Quality Patterns
A workflow earns its keep by CROSS-CHECKING, not by doing one big call. The
patterns below all lean on structured output. Each is a few lines of Starlark.
verify + repair + stop
Draft the answer, verify it with a SEPARATE schema'd worker, and on failure make
exactly one repair pass — then stop. Bounded, not an open loop. For code edits,
keep the edit/gate/repair loop inside one writable worktree worker, or use the
patch review pattern; do not do write_mode="direct" build followed by a second
direct repair leaf, because direct mode requires the repo to be clean before each
direct leaf.
artifact = agent("Draft the answer for " + args["task"], label="draft")
v = agent(
"Verify this answer for " + args["task"] + ". Did it pass?\n" + artifact,
schema={"ok": "bool", "problems": "problems, one per line"},
label="verify",
)
if v != Noneandnot v["ok"]:
raw = v["problems"] iftype(v["problems"]) == "string"else""
problems = [p.strip() for p in raw.splitlines() if p.strip()]
artifact = agent(
"Repair these problems in the answer:\n- " + "\n- ".join(problems) +
"\n\nCURRENT ANSWER:\n" + artifact,
label="repair",
)
# else: it passed (or verify failed to report) — stop. No unbounded retry loop.
adversarial verify (majority vote)
Do not ask one verifier "is this right?" — spawn N skeptics PER finding, each
prompted to REFUTE it, defaulting to refuted=true when unsure. Keep the finding
only if a MAJORITY do NOT refute. Survival-of-scrutiny beats a single rubber stamp.
N = 3
panel = parallel([
{
"prompt": "Try to REFUTE this claim: \"" + finding + "\". If you cannot " +
"confirm it, set refuted=true.",
"schema": {"refuted": "bool"},
"label": "skeptic",
}
for _ inrange(N)
])
refuted = 0for v in panel:
# Unsure / no-JSON defaults to refuted (conservative).ifnot (type(v) == "dict"and v["refuted"] == False):
refuted += 1
keep = refuted * 2 < N # majority did NOT refute
perspective-diverse verify
Same fan-out, but give each verifier a DISTINCT lens instead of N identical
refuters — a finding that survives correctness AND security AND reproduction is
far stronger than one that survives three clones.
lenses = ["is it logically correct?", "is it a security risk?", "does it actually reproduce?"]
checks = parallel([
{
"prompt": "Evaluate \"" + finding + "\" strictly on: " + lens,
"schema": {"ok": "bool", "why": "string"},
"label": "lens",
}
for lens in lenses
])
passed = [c for c in checks iftype(c) == "dict"and c["ok"]]
keep = len(passed) * 2 > len(lenses) # most lenses agree
judge panel
Generate N INDEPENDENT attempts from different angles, score each with parallel
judges, then synthesize from the winner. Use it when the answer is open-ended and
quality varies run-to-run.
angles = ["optimize for clarity", "optimize for performance", "optimize for safety"]
attempts = parallel([
{"prompt": "Solve " + args["task"] + ", " + a, "label": "attempt"} for a in angles
])
scores = parallel([
{
"prompt": "Score this solution 0-10 for " + args["task"] + ":\n" + attempts[i],
"schema": {"score": "int"},
"label": "judge",
}
for i inrange(len(attempts))
])
best, best_score = attempts[0], -1for i inrange(len(attempts)):
s = scores[i]["score"] iftype(scores[i]) == "dict"else -1if s > best_score:
best, best_score = attempts[i], s
agent("Refine and finalize this winning solution:\n" + best, label="synthesize")
loop-until-dry
Keep fanning out finders until K CONSECUTIVE rounds surface nothing new — a
seen set turns "find the bugs" into "find them all". Starlark has no while
loop (while is a reserved keyword that does not parse), so bound the hunt with
for _ in range(MAX_ROUNDS) and break once it converges. (break and
continue DO work in for loops; only while is missing.)
seen = {} # used as a set: finding -> True
dry_rounds = 0
K = 2# stop after K consecutive empty rounds
MAX_ROUNDS = 8# no `while` in Starlark: bound the loop, then break on convergencefor _ inrange(MAX_ROUNDS):
rounds = parallel([
{"prompt": "Find bugs in " + args["area"] + " NOT in this list:\n" +
"\n".join(seen.keys()),
"schema": {"findings": "findings, one per line"}, "label": "finder"}
for _ inrange(2)
])
fresh = 0for r in rounds:
iftype(r) == "dict"andtype(r["findings"]) == "string":
for f in [x.strip() for x in r["findings"].splitlines() if x.strip()]:
if f notin seen:
seen[f] = True
fresh += 1
dry_rounds = dry_rounds + 1if fresh == 0else0if dry_rounds >= K:
break
log("converged with " + str(len(seen)) + " distinct findings")
multi-modal sweep
The FIND-side counterpart of perspective-diverse verify: spawn finders that each
search a DIFFERENT WAY — by data flow, by failure mode, by entry point, by file —
each BLIND to what the others surface. One search angle never finds everything; a
sweep of orthogonal angles does. (The bug-hunt-verify example's three lenses are
exactly this.)
angles = [
"trace the data flow end to end and flag where it can go wrong",
"enumerate every external call and its failure mode",
"walk each public entry point and the inputs it fails to validate",
]
finds = parallel([
{"prompt": "Audit " + area + " by this method ONLY: " + a +
". Report concrete issues, one per line as `file:line — issue`.",
"schema": {"items": "the issues, one per line"}, "label": "sweep"}
for a in angles
])
completeness critic
End with one agent whose only job is to ask what is MISSING — the cheap final
guard against a confident-but-incomplete result.
gaps = agent(
"Here is the finding set for " + args["area"] + ":\n- " + "\n- ".join(seen.keys()) +
"\nWhat important cases are still MISSING?",
schema={"complete": "bool", "missing": "missing cases, one per line"},
label="completeness",
)
if gaps != Noneandnot gaps["complete"]:
raw = gaps["missing"] iftype(gaps["missing"]) == "string"else""
missing = [x.strip() for x in raw.splitlines() if x.strip()]
log("gaps remain: " + ", ".join(missing))
Error Tolerance
Workers fail or time out. agent() does NOT raise for that — it returns the
worker's (possibly empty) output, and in schema mode a failed/timed-out/garbled
worker returns None. So the script keeps running; YOU decide what a missing
result means:
Schema'd leaf: check if res == None: ... and skip / default conservatively
(e.g. count a missing skeptic vote as "refuted").
parallel(): the result list is always input-length, but some slots may be
None or a summary string — guard with type(x) == "dict" before indexing.
Never assume every slot in a fan-out succeeded; a robust workflow tolerates a
dead leaf and still reaches a verdict.
When the workflow needs to branch on the failure class itself, use
return_status=True instead of parsing text:
status = agent(
"Run a quick verifier for " + args["target"],
label="verify",
timeout_s=120,
return_status=True,
)
iftype(status) == "dict"and status["ok"] == False:
if status["reason"] == "timeout":
log("verifier timed out; run a cheaper fallback or mark coverage partial")
else:
log("verifier failed: " + status["reason"] + " " + status["detail"])
eliftype(status) == "dict":
log("verifier completed")
Use this for retry/abort/fallback logic. Use schema={...} when the worker
completed and the workflow needs typed domain facts.
Right-size it, and never cap silently
Scale the STRUCTURE to what was asked. "find any bugs" wants a few finders and a
single verify pass; "thoroughly audit X" wants a larger finder pool, a 3–5-vote
adversarial pass, and a synthesis stage. Do not bring a tournament to a one-line
question, and do not bring a single pass to "be exhaustive." When unsure, lean
thorough for review/audit/research and brief for a quick check.
And when you DO bound coverage — top-N, no retry, sampling, a fixed round count —
log() what you dropped. A silent cap reads as "covered everything" when it did
not; a logged one (log("scanned 50 of 120 files; stopped at the budget")) keeps
the run honest about what it actually checked.
When NOT To Use A Workflow
A single-step task is just one agent() call — wrapping it in a workflow(...)
program adds ceremony and buys nothing. A workflow's entire value is STRUCTURE:
parallelism, cross-checking (verify / adversarial / judge), or loops
(loop-until-dry). If your program has one agent() call and no branch, no
fan-out, and no loop, you do not want a workflow — you want that one call. Add the
structure only when the structure is the point.
Worked Example: the CANONICAL closed-loop skeleton
The shape a non-trivial workflow should follow — it composes ALL the idioms in
one program: a leading typed plan injected forward (json.encode), a shared
COMMON preamble, a bounded verify → refine loop against a schema'd bar, a
schema-gated branch (control flow keys off check["passed"], not prose), a
cheap model on the read-only verify step, a budget_usd ceiling, and a typed
verdict() so the run's status means intent met, not merely workers ran.
The runnable copy is examples/closed-loop.star; it
runs end-to-end under --dry-run (the verdict gate correctly reports Failed
when the bar is not met, even though every worker ran), and persists its log()
lines + verdict + criterion into the run's final_output.
A flat fan-out that only finds-and-reports is an ANTI-PATTERN: it cannot tell a
good run from an expensive single agent. Start from this skeleton and drop the
parts you do not need.
Worked Example: a writable build with a gate loop
The WRITABLE counterpart of the closed loop. Because a writable=True worker runs
in its OWN throwaway worktree, a separate implement step and verify step do not
share a tree — so the whole edit → run-the-gate → fix loop lives INSIDE one
writable worker (fed a leading typed design), while the PLAN and the verdict()
stay in Starlark. Its build prompt is the internal bar: a role, the injected
design as ground truth, hard constraints (never weaken a test), numbered
deliverables, the exact gate command, and a report contract.
examples/build-and-gate.star — runs under
--dry-run.
Worked Example: direct docs edit
examples/direct-doc-edit.star shows the
smallest direct-write shape: one serial writable leaf edits the selected project
root with write_mode="direct", then a read-only reviewer checks the requested
target and the workflow declares a verdict. This is for small docs/config edits
where the operator intentionally wants the current checkout changed now. It is
not a review-before-apply flow; direct-mode changes are already in the working
tree.
Worked Example: failure-aware retry
examples/failure-aware-retry.star shows
the P0 failure-control shape: a primary verifier uses return_status=True, the
script checks ok, reason, detail, and structured, and only then chooses a
fallback verifier. Use this whenever timeout/failure/malformed output should
change control flow; a negative domain verdict is not the same thing as a dead
leaf.
Worked Example: worktree patch, review, apply/reject
examples/patch-review-apply.star is the
default code-development shape for standalone run-script: implement in a
throwaway worktree, capture the diff as a pending WorkflowPatch, have a
schema'd review gate inspect the worker's diff/gate summary, then call
apply_patch(), reject_patch(), or no patch action. If the reviewer lacks
enough evidence, leave the patch pending for manual workflow patch show rather
than pretending reject means pending.
examples/pending-manual-review.star is
the dedicated pending variant. It creates the same durable patch, but when the
review evidence is incomplete or operator approval is still required, it makes
no apply_patch() / reject_patch() call and outputs the exact
workflow patch list/show/apply/reject commands for the operator. The workflow
finishes; the patch state remains pending.
Worked Example: artifact manifest
examples/artifact-manifest.star shows the
file-producing shape: a writable worker creates a declared repo-relative artifact,
expected_artifacts copies it out of the throwaway worktree, and
artifact_manifest() records existence, size, hash, and current/missing/stale
status for the dashboard.
Worked Example: bug hunt with adversarial verify
A quality workflow end to end: diverse schema'd finders fan out, every candidate
finding is cross-examined by a skeptic panel (majority must fail to refute), and
the confirmed set is synthesized. The runnable copy is
examples/bug-hunt-verify.star — it composes
structured output,
adversarial verify, and None-tolerant
flattening, and runs end-to-end under --dry-run.
Worked Example: data-driven scan, then parallel fix
A serial read-only scan call whose output decides the fan-out width: one fix
slot per defect line. Because the fix slots EDIT files in parallel, each sets
writable=True, which implies its own throwaway worktree and pending patch. The
runnable copy is
examples/scan-then-parallel-fix.star:
workflow(
"scan-then-parallel-fix",
"Scan once on the shared tree to enumerate defects, then fan out one isolated " +
"worktree fix per defect so the parallel fixes cannot collide on the same files.",
)
phase("scan")
scan = agent(
"Scan " + args["area"] + " for defects. Return a numbered list, one per line.",
provider="codex",
schema={"defects": "one defect per line"},
)
defects = []
iftype(scan) == "dict"andtype(scan["defects"]) == "string":
defects = [x.strip() for x in scan["defects"].splitlines() if x.strip()]
phase("fix")
fix_results = parallel([
{
"prompt": "Fix this defect in " + args["area"] + ": " + defects[i] + ". Make the minimal change and explain it.",
"provider": "codex",
"label": "fix:" + str(i + 1),
"writable": True,
"persist_changes": "patch",
"owned_paths": [args["area"]],
}
for i inrange(len(defects))
])
patch_labels = ["fix:" + str(i + 1) for i inrange(len(defects))]
output({"defects": "\n".join(defects), "pending_patch_labels": "\n".join(patch_labels)})
verdict(type(scan) == "dict", reason="created " + str(len(patch_labels)) + " pending patch(es)")
The scan phase completes before the
parallel barrier fans out, and each fix slot then runs concurrently in its own
worktree and joins before the run finalizes. Standalone run-script leaves one
pending patch per fix label; worktrees prevent checkout collisions, but patches
can still conflict later when applied to the live repo. The fan-out WIDTH is
decided at runtime from the scan's output — a comprehension over its lines —
which no static shape could express.
Worked Example: a design tournament (divergent → convergent)
The fullest divergent-then-convergent shape — the pattern the real internal
design runs use. Two parallel TYPED probes map the domain + the constraints;
three complete designs are generated from orthogonal philosophies, each seeded
with the understanding injected forward (json.encode); then a judge scores
them on named dimensions and grafts ONE winner. Every handoff is a multi-field
schema, so each step reads typed fields, not prose.
examples/design-tournament.star — runs under
--dry-run.
Worked Example: assess → adversarial-verify → synthesize (pipeline)
Evaluation as an ADVERSARIAL DIALOGUE, streamed with pipeline():
pipeline(dimensions, assess, verify) flows each dimension assess → verify with
NO barrier; the verifier is fed the assessment ({input} forward-injection) and
tries to REFUTE each claim, emitting a corrected verdict; then one report
synthesizes the VERIFIED verdicts. A single assessor over-claims — an independent
refuter that must consolidate a corrected verdict is what makes the synthesis
trustworthy. examples/assess-verify-synthesize.star
— runs under --dry-run.
Run It
Write the program to a file, then invoke the CLI. The program's provider values
drive delivery, so there is no member binding to pass:
Default workflow name; the workflow(...) header overrides it.
--args <json>
Injected as the args global.
--dry-run
Use a mock driver so the program runs end-to-end without spawning agents.
--start-runtime
Start the provider runtime if it is not already running.
--timeout-ms <ms>
Per-worker IDLE timeout (default 900000 = 15 min). A worker is killed only after this long with NO output — a slow-but-streaming turn runs to completion however long it takes; only a SILENT (wedged provider / auth or network stall) worker is killed. NOT a total wall-clock cap.
--max-budget-usd <amt>
Per-run spend ceiling; once cumulative cost reaches it, further leaves short-circuit into failed budget steps (also settable via workflow(budget_usd=…)).
--resume <prior_run_id>
Re-run the SAME program reusing the prior run's SUCCEEDED leaves (no re-spend); fails if the script changed.
Use timeout_s= for a per-leaf wall-clock cap; --timeout-ms remains the global idle-since-last-output timer and resets whenever the worker streams output.
| --trace durable\|live | Retain the heavy per-step turn-event trace (durable, default) or stream-only (live). |
| --model <m> | Run-wide default model; a per-call model= on an agent() overrides it. |
| --effort <e> | Run-wide default reasoning effort; a per-call effort= on an agent() overrides it. |
| --progress | Stream a compact NDJSON line per step (phase, label, running/ok/failed) to STDERR as the run executes — the phase-by-phase timeline — while STDOUT stays the single final JSON. |
The command prints the journaled run as JSON to STDOUT, including the new run
id and run.final_output (see the result-exit note below).
Read The Run Back
The run and its steps are persisted in the store and exposed on the dashboard.
Read them without raw JSONL reads via the snapshot, which carries workflow_runs
and workflow_steps:
Confirm: a WorkflowRun with your name, status moving running -> completed
(or failed), the declared design_intent, the snapshotted spec script,
args echoed back, and one WorkflowStep per agent call with its label,
phase, provider, and result. The same run renders on the Agent Dashboard
Workflows surface.
The result exit: how the calling agent gets the answer
You (the calling agent) invoke run-script through your shell tool, so you read
its result the way you read any CLI tool: its stdout becomes your tool result
when the command returns.run-script prints {"run": {...}, "steps": [...]},
and inside run.final_output:
result — what your output(value) declared. This is the run's answer;
read this one field. It is null if the script never called output().
verdict — {ok, reason} from verdict(): did the intent succeed.
success_criterion, logs — the declared bar and the log() narration.
steps[] — per-leaf output_summary (the worker's FULL reply, untruncated), structured, and
telemetry, for audit.
So a foreground call gives you the whole timeline + answer at once:
For LIVE tracking (which phase is running now), you cannot read a foreground
command's stdout mid-run — the shell tool returns it only on exit. Two options:
add --progress (NDJSON step events to stderr, which you still see in the
tool result) and/or run it in the background and poll harness dashboard snapshot (the journal updates per step live). End any answer-producing program
with output(...) so the answer is one field, not a step picked by label.
Observe a run: status + live progress
Pick by how live you need it:
Final result (foreground). The run-script call blocks and returns the whole
run as its tool result: run.final_output.result (the answer), run.status
(completed / failed), the verdict, and steps[] (per-leaf label, phase,
provider, status, output_summary). One call, whole timeline.
By id, any time / any shell.harness workflow get-output <run_id> prints a
run's ordered steps + status as JSON — --text for just the deliverable text,
--step <label> to filter to one leaf. The <run_id> (wfrun-…) is in the
run-script output; use this to inspect a run started in the background or another
session. Each step includes the journaled result plus session_summary
(tool_calls with counts, final_message, retained, truncated), so a
"completed but no artifact" leaf is diagnosable: did the worker call the tool,
and what did its final message say?
Live, phase-by-phase. Add --progress for one NDJSON line per step
(phase, label, running / ok / failed) on STDERR as it executes, and/or
background the run and poll harness dashboard snapshot (workflow_runs +
workflow_steps advance per step).
Visual / SSE. Point a live server at the SAME store
(harness serve --store <path>) and open the dashboard Workflows surface:
every run, a per-step timeline (status, provider, output_summary), and "drill in"
to a step's turn events, updating live over SSE. --trace durable (default)
retains the per-node trace; --trace live is stream-only.
Completion hook (push — for a backgrounded run). Set
HARNESS_WORKFLOW_ON_COMPLETE to a shell command and the harness fires it the
moment a run reaches a terminal status, passing HARNESS_RUN_ID /
HARNESS_RUN_STATUS (completed / failed) / HARNESS_RUN_NAME as env vars and
the full run JSON on stdin. It fires INSIDE the run-owning process at finalization,
so a backgrounded run-script & notifies WITHOUT the caller polling. No-op when
the var is unset; best-effort (a hook error is logged, never fails the run); keep
the hook quick (the run waits for it) or self-detach with a trailing &. E.g.
HARNESS_WORKFLOW_ON_COMPLETE='harness message send --from lead --content "wf $HARNESS_RUN_ID $HARNESS_RUN_STATUS"' harness workflow run-script prog.star &.
Scope: this hook is for run-script (and the stale-run reaper).
Permission Note
The agent that runs the program invokes the harness binary through its shell, so
its permission profile must allow it:
The runner's allowed-tool / command policy must permit running the harness
binary (for Claude this is a Bash(harness ...) allowance; for Codex the
sandbox/approval policy must let the shell call through).
Each agent call spins up a fresh ephemeral worker that is READ-ONLY in the
selected project root by default (#190). writable=True grants edit tools/full
provider permission; by default those writes go to a throwaway worktree.
write_mode="direct" is the explicit choice to write the selected repo cwd
immediately. A prompt that writes files or runs destructive / money-moving
actions executes for real once writable — scope prompts accordingly and keep
parallel mutations in worktrees.
Nested harness ... commands inside an ephemeral worker write a session-local
child store by default, not the parent project's central store. Use
HARNESS_WORKFLOW_ALLOW_STORE_MUTATION=1 harness workflow run-script ... only
when the leaf is explicitly trusted to mutate canonical harness objects.
If harness is not on the runner's PATH, invoke it by absolute path and
ensure that path is the allowed command.
Checklist
Program declares workflow(name, design_intent) once, before the body, with a real (>= ~20 char) design_intent.
Program calls only workflow/agent/parallel/pipeline/phase/log/verdict/output/args; no clock/random/IO assumed.
A program that produces an answer ends with output(value) so the caller reads final_output.result (a large answer goes through a schema'd dict, not capped free text).
Every agent leaf (agent() call / parallel spec) has a provider of "codex", "claude", or "kimi" (keep schema=-gated control-flow leaves on codex/claude).
Parallel slots that EDIT files use worktree isolation; never use direct mode in parallel/pipeline.
Writable code leaves declare owned_paths; leave default patch capture on unless the diff is intentionally throwaway.
Store mutation is explicit: ephemeral leaves do not write parent harness
objects unless the run is intentionally invoked with
HARNESS_WORKFLOW_ALLOW_STORE_MUTATION=1; otherwise the Lead records
evidence/proposals/decisions after reading the workflow result.
Writable file-producing leaves declare expected_artifacts and/or artifact_manifest with repo-relative paths.
If a workflow should decide landing internally, it has a review/gate leaf and calls apply_patch(label, reason) or reject_patch(label, reason) only for explicit apply/reject; insufficient evidence leaves the patch pending.
Every leaf whose output drives control flow uses schema={...} and the script handles a None (and, in fan-outs, a non-dict) result.
Any branch that depends on timeout/provider failure uses return_status=True and checks ok / reason / detail rather than parsing prose.
The standalone landing decision is explicit: run-script creates pending patches unless the script applies or rejects them, while write_mode="direct" changes the selected working tree immediately.
If the workflow has only one agent() call and no branch/fan-out/loop, it is NOT a workflow — collapse it to that one call.
Quality steps (verify / adversarial / judge / loop-until-dry / completeness) cross-check rather than trust a single pass, where the task warrants it.
Ran it: harness workflow run-script <prog.star> (no member binding needed).
The run is visible in harness dashboard snapshot (workflow_runs / workflow_steps) with its design_intent.
The runner's profile allows the harness binary and what each leaf's prompt does.
Maintaining This Skill
When updating this repository's skills/star-workflow copy, sync the installed
copies before accepting the task:
skills/star-workflow/scripts/sync-installed.sh
The script updates $CODEX_HOME/skills/star-workflow (or ~/.codex/skills by
default) and ~/.agents/skills/star-workflow, diffs both installed copies
against the repo copy, and runs quick_validate.py when the validator is
available. If an update should not be installed, record that as explicit evidence
and explain why.
