fs-anthropic-primitives

name

fs-anthropic-primitives

description

Domain reference for the Anthropic primitives the founder-skills plugins orchestrate, as used in THIS repo (not a textbook): the Workflow({scriptPath,args}) opt-in pattern and its injected-globals runtime, batched AskUserQuestion with the (Recommended) option first, the Agent() model-tier routing tables (Fable 5 plans/reviews, Opus 4.8 complex, Sonnet 4.6 standard, external executor cheap), output_config.effort vs the Task Budgets beta, /loop and /schedule and Claude Managed Agents scheduling, session-context.md tier persistence, and the canonical Anthropic doc-URL list with re-verify curls. Use when a maintainer asks "what does Workflow({scriptPath}) mean here", "which model implements vs plans", "what is the model routing table", "what's the difference between /effort and output_config.effort", "what is the task budgets beta", "how do these skills schedule recurring runs", "where is the effort tier persisted", "what URLs do these skills cite", or needs to edit any SKILL.md text that mentions Agent, Workflow, AskUserQuestion, Outcomes, model IDs, or Anthropic doc links.

fs-anthropic-primitives — the primitives these skills orchestrate, as used here

Announce at start: "Loading fs-anthropic-primitives — Anthropic primitives reference for founder-skills."

This repo's product is a "judgment layer": its plugins (15 as of 2026-07-02 — 12 committed + 3 uncommitted skill-*) tell Claude when and how to use Anthropic's execution primitives. To maintain the plugins you must know what each primitive is, exactly how this repo uses it, and which usage claims are verified vs still open. That is this skill. Everything below was checked against the repo files on 2026-07-02; claims that come from Anthropic docs were last content-verified against live official URLs on 2026-06-11 (the v0.2.0 fact-check) — that content check is now ~3 weeks stale. URL reachability was re-checked 2026-07-02 (see the URL table).

Definition — "primitive": a capability provided by Anthropic surfaces (Claude Code tools, slash commands, the Claude API, or Claude Managed Agents) that a skill invokes or instructs. The skills wrap primitives; they never reimplement them.

When NOT to use this skill

Your actual job	Load instead
Orient in the repo / find which skill covers X	fs-orientation
Understand WHY routing/no-oversell rules exist and their exact wording	fs-doctrine-and-honesty
Write or restyle a SKILL.md (voice, frontmatter, closers)	fs-skill-style-guide
Run the test suites / rebuild the venv / the JS harness commands	fs-toolchain-and-tests
Prove the unproven Workflow scripts end-to-end	fs-flagship-chain-campaign
Sweep for drifted model IDs / stale doc claims on a cadence	fs-freshness-watch
The history of how primitive claims went wrong before	fs-failure-archaeology

---

1. Workflow({scriptPath, args}) — the opt-in pattern

What it is: the Claude Code Workflow tool runs a bundled JS orchestration script that can spawn sub-agents. Two plugins ship such scripts:

Plugin	Script	Entry call (verbatim from SKILL.md)
market-validation	assets/research-workflow.js	Workflow({ scriptPath: "<skill-dir>/assets/research-workflow.js", args: { config: RunConfig, angles: [...] } })
build-options	assets/build-options-workflow.js	Workflow({ scriptPath: "<skill-dir>/assets/build-options-workflow.js", args: { context: DecisionContext, criteria: [...], lenses: [...] } })

The opt-in pattern (house convention): launching Workflow is allowed because the skill's own instructions tell you to call it — the tool's documented allowance. No separate user opt-in is needed beyond the user invoking the skill. Both SKILL.mds state this explicitly (market-validation SKILL.md:19–21, build-options SKILL.md:20). Preserve that sentence when editing.

Division of labor (spec rule R2): the skill (you, the orchestrating model) composes the inputs — angle set, criteria, lenses — and shows the spend-determining set to the user; the script only executes them. Scripts never invent research angles or scoring criteria.

Runtime contract (verified against plugins/market-validation/tests/js/harness.mjs, 2026-07-02): a Workflow script is NOT a standalone Node module. The runtime wraps the script body in an async function and injects the globals agent, parallel, phase, log, args. Consequences:

• Top-level await AND top-level return are legal inside the script (illegal in a plain ES module).
• You cannot import() or node the script to test it; the test harness replicates the wrapper with new Function('agent','parallel','phase','log','args', ...) and stubbed globals.
• Therefore node --test 'tests/js/*.test.mjs' (glob form only — directory form fails, defect ledger #3) is the ONLY way to exercise the shipped script offline.

Honesty status (do not weaken this): both scripts were proven on 2026-07-02 (campaign Phase 1 spec); before that they were self-declared "syntax-checked only — its first real invocation is its proving run" (market-validation SKILL.md:93, build-options SKILL.md:63; defect ledger #4). They were rewritten 2026-06-11 to read args.* but have only ever executed in an earlier hardcoded form. The gated proving run belongs to fs-flagship-chain-campaign. Until it passes, no SKILL.md, README, or site copy may claim the generalized scripts "work".

2. AskUserQuestion — batched, (Recommended) first

What it is: the Claude Code interactive-mode tool that presents structured multiple-choice questions. House conventions (extracted from the golden four + calibration skills):

• Batch questions into ONE call. session-start asks 3 questions in a single call; market-validation Phase 0 asks its 3 scope questions in one call. Never serialize one-question-per-call when the questions are known upfront.
• The recommended option comes FIRST and is labeled (Recommended) — e.g. effort's "Ample — Opus 4.8 (Recommended for new work)", session-start's "Quick exploration (Recommended for most sessions)".
• Skills embed the question as a literal fenced block (header / question / options with label + description), so any model can reproduce it verbatim.
• Every option's description states the consequence (which model, what cost), not marketing.

3. Agent() and the model-tier routing tables

What it is: spawning a sub-agent on a named model. The repo's core doctrine rides on it: Fable plans, orchestrates, and reviews — Fable never writes implementation code (rationale and exact wording: fs-doctrine-and-honesty).

Canonical model table (verbatim IDs from fable-orchestrated-feature-dev SKILL.md "Model Reference", verified 2026-07-02 — these IDs are hardcoded prose and WILL drift; fs-freshness-watch owns re-checking them):

Model ID	Alias in Agent({model})	Role in this repo	Cost tier
claude-fable-5	fable	Planner, orchestrator, reviewer, auditor — never coder	High
claude-opus-4-8	opus	Implementer — complex features, ample budget	High
claude-sonnet-4-6	sonnet	Implementer — standard work; also the independent verifier/grader in loops	Medium
External executor	— (plan-file handoff, not an Agent call)	Token-exhausted fallback: a cheaper Claude session, Haiku 4.5, or a third-party plan-runner "such as Codex"	Minimal

Session-tier → routing (two tables exist; both are canonical for their skill):

effort tier	Routing announced
Ample	Planning + implementation → Opus 4.8
Moderate	Planning → Opus 4.8, implementation → Sonnet 4.6
Constrained	All → Sonnet 4.6; heavy lifts → external executor via plan file
Sprint end	Plans only; ALL implementation → external executor

session-start tier	Fable planning	Implementation	Review
Quick	Sonnet 4.6	Sonnet 4.6	Sonnet 4.6
Focused	Opus 4.8	Sonnet 4.6	Opus 4.8
Deep	Opus 4.8	Opus 4.8	Opus 4.8
Constrained	Sonnet 4.6	Sonnet 4.6 → external executor	Sonnet 4.6

Recurring Agent() patterns you must preserve when editing:

• Plan-file handoff: Fable's planner Agent returns only an absolute file path (~/.claude/plans/<slug>-<date>.md); handoffs pass file paths, never inline content.
• Independent verifier: loop graders run on a different model in a fresh context (fable-loop-design: model: "sonnet" grades Fable's output). Official basis: "Separate fresh-context verifier sub-agents tend to outperform self-critique" (migration guide, content-verified 2026-06-11).
• Sanitization: Codex may only be named as an example — "such as Codex" — never as a hard dependency (doctrine; the prd/tasks agent-browser dependency is the known violation, licensed for rewrite).

4. output_config.effort vs Task Budgets (don't confuse with /effort)

Three different things share the word "effort". The disambiguation table (source: effort SKILL.md "Related API primitives", spec item 4; content-verified 2026-06-11):

Thing	Level	What it controls
/effort skill (this repo)	Session	Which MODEL handles each role; persisted to session-context.md
output_config.effort (low/medium/high/xhigh/max)	Per API request	Thinking depth / token spend within one request
Task Budgets — output_config.task_budget, beta header task-budgets-2026-03-13, min 20,000 tokens	Per agentic loop	A model-visible token countdown; the model self-moderates

Officially documented lever the Constrained tier relies on (as of 2026-06-11): on Fable 5, lower effort settings still perform very well — often exceeding the xhigh/max performance of previous models — so dial output_config.effort down before downgrading models.

5. Loops and scheduling: /goal, /loop, /schedule, Claude Managed Agents

As used by fable-loop-design and fable-org-audit (all content-verified 2026-06-11 via the primitives-upgrade spec):

Primitive	Surface	Use here
/goal	Claude Code	Sets the direction for a run (restored to the docs per the migration guide)
/loop	Claude Code	Re-runs a prompt/slash command until stopped — the built-in loop harness for standard self-correction
/schedule (routines)	Claude Code	Cron-cadence runs on Anthropic-managed cloud infra (laptop can be off) — the default weekly org-audit trigger
Outcomes	Claude Managed Agents (CMA)	Hosted iterate → grade → revise loop. Send a user.define_outcome EVENT on an existing session (not a session-create field; don't also send a kickoff user.message). Rubric REQUIRED (`{type:"text"
Scheduled deployments	CMA	deployments.create() with cron expression + IANA timezone; each firing writes a deployment_run record with typed errors; test with manual deployments.run() first
Memory stores	CMA	Workspace-scoped filesystem mounted into sessions; per-mutation versioning — the hosted analog of the local memory/ progression

Bridge pattern (spec item 3): a plan file's machine-verifiable acceptance criteria (what tasks produces) ARE an Outcomes rubric — extract them to markdown and send user.define_outcome. This "hosted executor" path is described, not yet exercised in this repo. UNVERIFIED beyond docs.

Safety boundary (spec item 5, applies to Fable audit skills): Fable 5's safety classifiers can false-positive on security-adjacent audit work. A decline arrives as HTTP 200 with stop_reason: "refusal" (pre-output refusals unbilled) — not an error. On the API, fallback to Opus 4.8 is opt-in (beta fallbacks param, SDK middleware, or manual retry); consumer surfaces handle it automatically. Skills must report a refused section as refused, never silently skip it.

6. session-context.md — tier persistence

The effort tier is set ONCE (via /effort or /session-start) and persisted to ~/.claude/session-context.md (environment-specific path — the user-level Claude Code home; this is the actual mechanism, not an example). Downstream skills read it instead of re-asking.

Known seam (verified 2026-07-02, unresolved): the two writers disagree on semantics — effort SKILL.md:51 says "append or overwrite the effort_tier line"; session-start SKILL.md:81 says "overwrite each session — this is a scratchpad, not memory". Both cannot be literally true of one file. Treat as an open consistency defect if you touch either skill; fixing it requires a spec (fs-change-control).

Distinct from session-context.md: the Claude Code memory system (~/.claude/projects/<project>/memory/MEMORY.md) which session-start Step 4 reads for pending items, and the memory/rules.md progression fable-loop-design designs. Don't conflate the three.

7. Canonical doc-URL list + re-verify curls

Every Anthropic-doc claim in this repo must trace to one of these official URLs (doctrine). Last FULL content verification: 2026-06-11 (curl 2xx + content check, per the v0.2.0 spec) — stale as of 2026-07-02. Reachability only (HTTP 200 via curl -L, content NOT re-checked) confirmed 2026-07-02 for all eleven URLs below.

URL	Cited by (repo-verified 2026-07-02, incl. the 3 uncommitted skill-* plugins)
https://code.claude.com/docs/en/skills	11 plugin READMEs ("built on" tables, incl. skill-style-guide) + docs/index.html
https://code.claude.com/docs/en/sub-agents	7 plugin READMEs + README.md + docs/index.html
https://code.claude.com/docs/en/interactive-mode	effort, session-start SKILL.mds + READMEs; all 3 skill-* READMEs
https://code.claude.com/docs/en/agent-sdk/overview	session-start SKILL.md + READMEs
https://code.claude.com/docs/en/memory	session-start SKILL.md + READMEs
https://code.claude.com/docs/en/slash-commands	README.md + docs/index.html
https://code.claude.com/docs/en/overview	docs/index.html + prd README
https://code.claude.com/docs/en/plugins	docs/index.html + superpowers spec/plan + skill-release-gate SKILL/README + skill-style-guide README
https://code.claude.com/docs/en/plugin-marketplaces	docs/index.html + superpowers spec/plan + skill-release-gate SKILL/README + skill-style-guide README
https://platform.claude.com/docs/en/docs/about-claude/models/overview	effort, session-start SKILL.mds + READMEs; skill-freshness-watch SKILL/README
https://platform.claude.com/docs/en/docs/agents-and-tools/tool-use/overview	README.md + market-validation README + docs/index.html

One-line reachability sweep (run from repo root; expect eleven 200s — the count itself is a drift signal: if it changes, a citation was added or removed somewhere). Note the character class excludes backticks: a backtick-wrapped URL (e.g. skill-freshness-watch cites the models page inside `) would otherwise be captured with a trailing ` and curl as a phantom HTTP 400:

grep -rhoE 'https://(code|platform)\.claude\.com[^ )>"'"'"'`]*' README.md docs plugins | sed 's/[.,]$//' | sort -u | while read u; do printf '%s ' "$u"; curl -s -o /dev/null -w '%{http_code}\n' -L --max-time 20 "$u"; done

A 200 proves the page exists, NOT that the fact still holds. Facts that need periodic content re-verification (owner: fs-freshness-watch): the Task Budgets beta header/date and 20k minimum, output_config.effort level names, Outcomes event shape and iteration limits, the stop_reason: "refusal" + fallbacks behavior, the "low effort on Fable 5 still performs very well" claim, and every hardcoded model ID (claude-fable-5, claude-opus-4-8, claude-sonnet-4-6, "Haiku 4.5").

Common mistakes

Mistake	Fix
Testing a Workflow script with node script.js or import()	It has top-level return; use the harness via node --test 'tests/js/*.test.mjs' (glob form only)
Claiming the generalized Workflow scripts work	They are "syntax-checked only" until the fs-flagship-chain-campaign proving run passes
Serializing AskUserQuestion calls	Batch known questions into one call; (Recommended) option first
Letting Fable emit implementation code	Doctrine violation — see fs-doctrine-and-honesty; prompts must say "planning only"
Confusing /effort with output_config.effort or Task Budgets	Section 4 table: session routing vs per-request depth vs loop countdown
Treating stop_reason: "refusal" as a crash or empty result	Check stop_reason; report the section as refused; fallback is opt-in on the API
Adding a doc claim with no URL, or a URL verified "sometime"	Verify the live URL that session and date-stamp it (doctrine)
Editing model IDs in one skill only	They are hardcoded across effort, session-start, fable-* SKILL.mds and docs/index.html — sweep all (fs-freshness-watch)

Provenance and maintenance

Sources read 2026-07-02: plugins/effort/SKILL.md, plugins/session-start/SKILL.md, plugins/fable-loop-design/SKILL.md, plugins/fable-orchestrated-feature-dev/SKILL.md, plugins/fable-org-audit/SKILL.md, plugins/market-validation/SKILL.md (+ tests/js/harness.mjs), plugins/build-options/SKILL.md, docs/superpowers/specs/2026-06-11-anthropic-primitives-upgrade.md.

Re-verify before trusting (one line each):

# Workflow call signatures still as documented here
grep -rn "Workflow({" plugins/market-validation/SKILL.md plugins/build-options/SKILL.md
# "syntax-checked only" admissions still present (if gone, the proving run happened — update §1)
grep -rn "syntax-checked only" plugins/*/SKILL.md
# Injected-globals runtime contract unchanged
sed -n '1,12p' plugins/market-validation/tests/js/harness.mjs
# Model IDs and routing tables unchanged
grep -rn "claude-fable-5\|claude-opus-4-8\|claude-sonnet-4-6" plugins/*/SKILL.md
# Task Budgets beta + effort levels as stated
grep -n "task-budgets-2026-03-13\|xhigh" plugins/effort/SKILL.md
# Outcomes / scheduling facts as stated
grep -n "user.define_outcome\|max_iterations\|deployments.create" plugins/fable-loop-design/SKILL.md plugins/fable-org-audit/SKILL.md plugins/fable-orchestrated-feature-dev/SKILL.md
# session-context.md writers (and the append-vs-overwrite seam)
grep -rn "session-context" plugins/effort/SKILL.md plugins/session-start/SKILL.md
# URL reachability sweep — see §7 one-liner; expect all 200s

Volatile date-stamps in this file: repo facts 2026-07-02; Anthropic-doc content facts 2026-06-11 (stale); URL reachability 2026-07-02. If any grep above disagrees with this skill, the repo wins — update this file via the fs-change-control pipeline (internal .claude/skills/ edits still get operator review before commit; assistants run no mutating git commands).