fix(poteto-mode): resolve principle leaves by sibling path

[ngctro]

Why

Agents working in poteto mode could not find principle leaf skills. They searched wrong directories and concluded the principles only exist inside the poteto-mode skill file.

Scope

The Principles section of skills/poteto-mode/SKILL.md now states the resolution rule. All principle skills carry disable-model-invocation: true, which pi honors by hiding them from the system prompt entirely. The original Cursor pstack uses the same flag and the same sibling layout, so the port dropped nothing. The missing piece was a name-to-path mapping inside the artifact. The section now says each bold name below is also the name of a sibling directory of the skill, with ../principle-laziness-protocol/SKILL.md as the example.

Tradeoffs

Registering the leaves would make them discoverable by name but would add 24 descriptions to every session prompt across all projects. The path rule keeps that context cost at zero and works from any cwd because it anchors on the loaded skill's own directory.

Blast Radius

One sentence block in one file. Readers of poteto-mode in any harness get the same rule. Subagents still receive resolved file pointers from the parent, unchanged.

Verification

Extracted every principle-* reference across poteto-mode, its playbooks, its references, no-comments, and docs, and resolved each against the anchor directory with the stated rule. 21 of 21 referenced names map to existing leaf SKILL.md files. An earlier draft of the line used a placeholder token that a mechanical resolver tripped over; reworded to a real example. node scripts/validate.mjs passes on all 49 skills.

[ngctro]

Independent pre-merge verdict: PASS.

• Diff read in full. It touches only skills/poteto-mode/SKILL.md and adds a concrete resolution rule anchored on the skill's own directory ("Each bold name below is also the name of a sibling directory of this skill", example ../principle-laziness-protocol/SKILL.md).
• Example path resolves from the checkout: skills/principle-laziness-protocol/SKILL.md exists.
• Principle references: 21 distinct principle-<name> tokens across skills/ and docs/, all 21 map to existing skills/principle-/SKILL.md files, and all 21 dirs carry disable-model-invocation: true as the new text claims. 0 orphans in either direction.
• Validator: ok: 49 skills, 2 agents, 2 manifest paths (exit 0).
• Added text is clean: no narrating comments, no em-dashes, no mid-sentence colons (the only colon is inside the code span disable-model-invocation: true).

Not merged; no files modified.