fix(skills): make argument-hint a YAML string, not a one-element list

[thejesh23]

Summary

All 9 SKILL.md files in plugins/donegraph/skills/ write argument-hint as a flow-sequence rather than a string:

# Before (parses as a one-element list ["..."])
argument-hint: ["<goal> [--platform codex|claude|cursor|generic]"]

# After (parses as a string "...")
argument-hint: "<goal> [--platform codex|claude|cursor|generic]"

The bug

In YAML, a bare [ opens a flow-sequence. So argument-hint: ["X"] deserialises to the list ["X"], not to the string "X". Skill loaders that expect argument-hint to be a string therefore see the wrong type and reject the skill.

GitHub Copilot CLI 1.0.65 (released 2026-06) tightened its skill loader to require argument-hint to be a string. As a result, every DoneGraph slash command silently fails to load in Copilot CLI 1.0.65+.

Verified locally:

>>> import yaml
>>> yaml.safe_load('argument-hint: ["[--no-open]"]')
{'argument-hint': ['[--no-open]']}   # list, len == 1
>>> yaml.safe_load('argument-hint: "[--no-open]"')
{'argument-hint': '[--no-open]'}     # str

The fix

Strip the outer [ and ] in all 9 files under plugins/donegraph/skills/:

• donegraph/SKILL.md
• donegraph-capture/SKILL.md
• donegraph-checkpoint/SKILL.md
• donegraph-dashboard/SKILL.md
• donegraph-done/SKILL.md
• donegraph-proof/SKILL.md
• donegraph-recap/SKILL.md
• donegraph-start/SKILL.md
• donegraph-summary/SKILL.md

One logical change per file, one commit total.

Why this shape (string, not array)

• VS Code Agent Skills docs — argument-hint is documented as a single-line prompt hint (string), matching how it renders in the slash-command picker.
• Copilot CLI skills tutorial (copilot-cli-for-beginners/05-skills) — shows argument-hint as a plain YAML string in every example.
• Also latent on Claude Code — see anthropics/claude-code#22161. Claude Code today accepts either shape, but the documented contract is a string. Fixing this now removes the exposure before Claude Code tightens too.

Test plan

• git diff main -- 'plugins/donegraph/skills/**/SKILL.md' — should show 9 files, each with a one-line change: ["..."] → "...".

• Frontmatter sanity check — every file's argument-hint deserialises to str:

  python3 -c '
  import yaml, glob, re, sys
  ok = True
  for f in sorted(glob.glob("plugins/donegraph/skills/*/SKILL.md")):
      fm = yaml.safe_load(re.match(r"^---\n(.*?)\n---", open(f).read(), re.DOTALL).group(1))
      t = type(fm["argument-hint"]).__name__
      print(f"{f}: {t}")
      if t != "str": ok = False
  sys.exit(0 if ok else 1)
  '

• Copilot CLI 1.0.65+ — install the plugin, run copilot in a project, confirm /donegraph, /donegraph-recap, etc. all appear in the slash-command picker (before this PR, none of them load).

• Claude Code — confirm the skills still load (Claude Code accepts both shapes today, so no regression expected).

• Repo checks per CONTRIBUTING.md:

  • npm test — pure frontmatter change, no code paths touched; no impact expected.
  • npm run typecheck — no .ts files changed.
  • npm run build — no build inputs changed.
  • Prettier (from .github/workflows/ci.yml) — I ran npx prettier --check on both the pre-patch and post-patch trees; the same set of pre-existing warnings appear either way (2 files after this PR vs 3 before; this PR incidentally fixes one). No new warnings introduced. The CI step is guarded with || echo "Prettier not configured, skipping" and will not fail regardless.

Scope

• Files touched: only the 9 SKILL.md files listed above.
• Behaviour change: none, other than the skills now actually loading in Copilot CLI 1.0.65+.
• Schema / privacy / determinism constraints from CONTRIBUTING.md: unaffected — no code-graph edges introduced, no render path touched, no snapshot fields added.

[thejesh23]

Tracking issue: #2 — captures the bug diagnosis and reproducer separately for anyone searching the repo who lands there before this PR.