purpose-properties

Purpose Properties Skill

Retrofit and re-derive entry point for purpose.yml#purpose_properties. For new projects this runs inside /mycelium:start Step 3b. Use this skill when:

• The project existed before v0.120.0 and has no purpose_properties (the retrofit case — every project created before that release, since /mycelium:start Step 4 exits for already-initialized projects and never reaches the extraction).
• why, how or what changed, so derived_from_hash no longer matches and every stance below it is superseded (the drift case — this is the one that matters most and the easiest to skip).
• A property list exists but the user wants to revisit which properties are binding.

Full contract: ${CLAUDE_PLUGIN_ROOT}/../../docs/purpose-stance.md.

Step 1: Read the current state and say which case this is

Read purpose.yml. Then say plainly which of these you are in, because the three have different consequences and the user should not have to infer it:

• No purpose_properties → retrofit. Nothing below has ever been checked against the purpose.
• Hash mismatch → drift. Report it as "your purpose changed after these were derived, so every purpose_stance below them was reasoned under a definition you have since changed." This is the state that quietly invalidates work; name it in those terms.
• Hash matches → nothing to do. Report the property count and stop. Do not re-derive for tidiness.

Step 2: Attempt extraction, and classify what fails

For every element of why, how and what, ask: can I name a specific solution that would CONTRADICT this?

• Yes → candidate property. Record property, verbatim (their words, not yours), source, and the contradicting solution in contradicted_by.
• No → do not force one. Quality adjectives — secure, accessible, fast, simple, delightful, robust — yield nothing checkable, because every candidate solution claims to satisfy them.

Measured 2026-08-23, blind: "accessible and secure" produced no checkable property, while five abstract framework principles produced clean ones. The axis is not abstract vs concrete — it is quality adjective vs structural claim. Do not treat concrete-sounding words as safe.