Convert forge commands to skills (cross-platform)

[dasirra]

Summary

Converts forge's three commands into skills so one source tree runs natively on both Claude Code and Pi. A skill is the unit both harnesses understand: on Claude Code a skill is a superset of a command (explicit /forge:building #3 invocation via disable-model-invocation: true, plus $ARGUMENTS); on Pi, skills are the native unit. This removes the command/skill bridge entirely, no drift.

Stacked on #8. Base branch is building/issue-3, so this diff is only the conversion. Merge #8 first, then retarget this to main (or rebase). This branch's binding-doc versions supersede #8's, which still say "commands."

What changed

• commands/{interview,planning,building}.md -> skills/{interview,planning,building}/SKILL.md. Directory is the bare workflow name so the forge plugin namespaces invocation to /forge:<name> (verified against Claude Code docs: skills/forge-building/ would have wrongly produced /forge:forge-building).
• Frontmatter is now name + description + disable-model-invocation: true (explicit-only). Bodies preserved verbatim plus one argument-fallback line for harnesses that do not substitute $ARGUMENTS.
• package.json added, declaring "pi": { "skills": ["./skills"] }.
• README/manifest wording: "commands" -> "skills".
• Binding docs retargeted at skills/*/SKILL.md; the depth-relative binding link fixed (../ -> ../../ now that files live one level deeper).

How it was built

Subagent-driven development: a fresh implementer per task, a spec+quality review after each, and an opus whole-branch review at the end. Two defects the process caught that a straight edit would have shipped:

1. Task 1 (naming verification) caught the wrong directory pattern before any conversion ran (/forge:forge-building doubling).
2. The final whole-branch review caught the depth-relative binding link breaking on the commands/ -> skills/ move, which the per-task "byte-identical body" gates structurally could not see.

Design spec and implementation plan are included under docs/specs/ and docs/plans/.

Not included (deferred, needs live harnesses)

• Task 8: Claude Code invocation parity check (/forge:* invokes explicitly, $ARGUMENTS arrives, no auto-trigger).
• Task 9: Pi validation (install, invoke, confirm binding resolution) which also resolves the last two open items: does Pi pass $ARGUMENTS, and does Pi tolerate disable-model-invocation.

Also out of scope: the skill bodies still self-refer as "This command" (byte-identical preserved it), and README.md/docs/pipeline.html still mention the removed /code-review Phase 8.

[Copilot]

Pull request overview

This pull request converts forge’s three workflow entrypoints from Claude Code “commands” into cross-platform “skills” so the same source tree can be consumed natively by both Claude Code and Pi, eliminating a command/skill bridging layer.

Changes:

• Migrate the three workflows to skills/<workflow>/SKILL.md and add skill frontmatter (name, description, disable-model-invocation: true), plus an $ARGUMENTS fallback instruction.
• Add a Pi manifest (package.json) pointing Pi at ./skills.
• Update docs/bindings/README wording and fix binding-doc links for the new file depth.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
skills/interview/SKILL.md	Converts interview workflow into a skill; adjusts binding link depth; adds $ARGUMENTS fallback line.
skills/planning/SKILL.md	Converts planning workflow into a skill; adjusts binding link depth; adds $ARGUMENTS fallback line.
skills/building/SKILL.md	Converts building workflow into a skill; adjusts binding link depth; adds $ARGUMENTS fallback line.
README.md	Renames “commands” to “skills” in user-facing docs and usage table.
package.json	Adds Pi package manifest declaring pi.skills directory.
docs/specs/2026-07-11-forge-skills-conversion-design.md	Captures the design/spec for the conversion.
docs/plans/task1-naming-findings.md	Records naming/discovery findings from Claude Code + agentskills.io docs.
docs/plans/2026-07-11-forge-skills-conversion.md	Provides an implementation plan for the conversion tasks and verification steps.
docs/harness-bindings/README.md	Updates harness-binding overview to reference skills instead of commands.
docs/harness-bindings/pi.md	Updates Pi binding doc references from commands to skills.
docs/harness-bindings/claude-code.md	Updates Claude Code binding doc references from commands to skills.

Comments suppressed due to low confidence (3)

skills/planning/SKILL.md:27

• This fallback line changes the documented meaning of an intentionally empty $ARGUMENTS (the section below defines Empty as “use the current conversation”). On Claude Code, invoking /forge:planning with no args would make $ARGUMENTS empty and this line would incorrectly instruct treating the user's request text as the arguments instead of honoring the empty-case semantics.
  skills/interview/SKILL.md:24
• This fallback line overrides the intended empty-arguments behavior defined immediately below (Empty means “use the current conversation”). If /forge:interview is invoked with no args on a harness that does substitute $ARGUMENTS to an empty string, this instruction conflicts with the documented interpretation rules.
  skills/building/SKILL.md:26
• This fallback instruction triggers when $ARGUMENTS is empty, which can happen on harnesses that correctly substitute arguments but are invoked with no args. That can change the skill’s behavior in the empty-args case; the fallback should only apply when $ARGUMENTS was not substituted (i.e., still appears literally).

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