kasparovabi Mythos scaffold
Agentic discipline framework anchored by working patterns distilled from Claude Fable 5 itself (2026-07-06, revised 2026-07-21). v2 adds a persistent mission file, harness-enforced persistence (Stop/SessionStart hooks), named worker agents with explicit model routing, a headless profile, and an eval harness that measures the scaffold instead of trusting it.
Honest expectation: the scaffold transfers process discipline, not capability. It makes
Opus 4.8 a disciplined Opus 4.8. See eval/ for measured deltas.
Model gating (check first)
| Session model | What to load |
|---|---|
| Opus 4.8 / Opus 4.x / Sonnet 4.x / Haiku | Kernel, then tiered (below) |
| Claude 5 family (Fable 5 / Mythos 5 / Opus 5 / Sonnet 5) and later | Nothing, or at most the kernel's verification section. State goal and constraints; do not enumerate steps. |
When in doubt (a model newer than this table): treat it as Claude 5 family — under-scaffolding costs less than over-scaffolding on capable models.
Activation
Always load exactly one file: the kernel, core/fable-distilled.md.
It carries the binding rules and the load map for every other file (mode, tool-stack,
context-priming, decomposition, agent-loop, verification, failure-recovery, memory, headless,
domains). Open others only when their load-map trigger fires.
Mission file
Long-horizon runs externalize state to ~/.claude/mythos/missions/<slug>--<stamp>.md with an
active-mission pointer at ~/.cache/mythos/active. The /mythos-mode command owns the
lifecycle (<task> / resume / status / close); the hooks in hooks/ read
it to block premature stops and to re-surface the mission after compaction. Schema: see the
command's mission template.
Sub-agents
agents/ ships four workers installed into ~/.claude/agents/: mythos-scout
(haiku, mechanical bulk), mythos-builder (sonnet, light code), mythos-heavy (opus, hard
code), mythos-verifier (sonnet, adversarial check, never edits). Every spawn names its
model explicitly.
Domain modes
- Research:
domains/research/(retrieval tiers, claim graph, cite-verify, output formats) - Migration:
domains/migration/(audit, plan, execute, rollback)
Integration
The scaffold routes to neighbors instead of duplicating them: see
INTEGRATION.md.
When to use
- Multi-step tasks where the model might stall, drift, or miss verification
- Long-horizon research or migrations (domain modes)
- Debugging cycles where naive retry fails
- Unattended runs (cron, loops):
core/headless.md
When not to use
- Single tool call, single answer questions: overhead not worth it
- Tasks already covered by a more specific skill
- Sessions running on Claude 5 family models — Fable 5 / Mythos 5 / Opus 5 / Sonnet 5 (model gating above)
Changelog
- 2026-07-21 (v0.3): kernel recompiled (mode rules folded in, context economy, escalation
protocol); mission file + pointer; Stop/SessionStart enforcement hooks; four named worker
agents; headless profile; eval harness (T1 persistence, T2 verification) and distillation
curation procedure; command grows
resume/status/close; installed command becomes a symlink; stale references fixed; dead sync hook removed. - 2026-07-06: Fable-distilled patterns added; read-all-8 replaced with tiered loading; model gating; sub-agent model routing.
- 2026-04-27: initial 6-skill framework plus research and migration domains.
Source
https://github.com/kasparovabi/claude-mythos-scaffold (MIT, by kasparovabi). Inspired by Claude Mythos Preview behaviors, not affiliated with Anthropic.