Spec alignment sweep: propagate settled conventions across framework, template, build skill and saddler

[dilberryhoundog]

Conventions are guiding lights the rest of the spec must align with. Once conventions.md settles, everything downstream needs bringing into line. Nothing here should start before that.

Blocked on: finalising conventions.md.

Surfaces to sweep

• docs/drafthorse/framework/ — steps.md, notation.md, scaffold.md, surfaces.md, references.md, handover.md, README.md.
• docs/drafthorse/drafthorse-spec-check.md.
• extensions/skills/drafthorse/SKILL.md — in particular the Conventions Digest, which is the build skill's working copy of the conventions.
• extensions/skills/drafthorse/references/ — condition-writing.md, step-splitting.md, collecting-references.md.
• extensions/skills/drafthorse/assets/SKILL-template.md and HANDOVER-template.md.
• extensions/agents/drafthorse-saddler.md.
• extensions/rules/DraftHorse.md.

Known specific items

• Apply the ### Dispositions replacement proposed inline in steps.md, once approved.
• Land the three convention→instruction migrations with a verified home for each.
• Widen the digest entry at drafthorse/SKILL.md:46 from half-applied state to any failure, and split it into its own discrete test so the scenario-walk at :196 can sweep it. The rule is currently a subordinate clause inside a longer sentence about subtractive coverage, which is why it is read past.
• Add the disposition text to the error step shipped in SKILL-template.md. The template currently names half-applied state but never states what to do about it; the full rule lives only in steps.md, which a drafting agent need not open. A document can grow a per-step resume path and still pass the template.
• Add to +Draft the Skill (drafthorse/SKILL.md:180): no working step handles its own failure; every failure disposition belongs to the error step.
• Sharpen +Review's walk instruction (:196) to name the check — at each failure entry, confirm the failing step simply cannot finish and the error step claims it.
• Widen saddler's check at drafthorse-saddler.md:136 from half-applied state to any failure, matching the digest so builder and auditor test the same thing.
• Harden the Stepping stones sub-bullet "leaving that step to focus on its jobs instead of handling every state it might produce" into an enforceable rule. As written it states a benefit, so it will not stop an author and saddler cannot check it.
• drafthorse/SKILL.md's own steps write their condition blocks as prose rather than lists. The build skill should conform to its own spec.

Origin

Surfaced by a saddler audit of extensions/skills/versioning/SKILL.md, which found +Execute handling its own half-applied state — a start-condition resume clause, an inventory-and-continue engagement, and an invariant licensing partial re-application. Chasing that one defect showed the convention was demonstrated three times in steps.md and stated nowhere as a law.