feat(kyberforge): add skill-improve skill to factory workflow

Applies evidence-based improvements to existing skills using signals
from grill sessions, audit reports, eval failures, and inline feedback.
Groups signals by root cause before editing to avoid per-symptom patching.
Hands off to /skill-audit on completion.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/kyberforge/skills/skill-improve/README.md

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+# skill-improve
+
+Apply evidence-based improvements to an existing skill using signals from the current session.
+
+## What it does
+
+Takes an existing skill directory and one or more improvement signals — grill output, audit findings, eval failures, human feedback, or inline session context — and applies targeted edits to the skill files. Groups signals by root cause before editing to avoid per-symptom patching. Hands off to `/skill-audit` when done.
+
+## Before you start
+
+Have at least one improvement signal ready: a grill session output, `/skill-audit` report, eval results, feedback.json, or inline feedback describing what went wrong. If you have no signals and want a blind review, use `/skill-audit` instead.
+
+## Usage
+
+```
+/skill-improve
+```
+
+Provide the skill directory path and any signal files in the conversation. The skill gathers signals from context — you don't need to paste them in a specific format.
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `SKILL.md` | Skill instructions for agents |

plugins/kyberforge/skills/skill-improve/SKILL.md

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+---
+name: skill-improve
+description: >
+  Apply evidence-based improvements to an existing skill. Use when the user
+  says "improve this skill", "fix this skill based on feedback", "apply these
+  audit findings", or "update the skill based on this grill output". Also use
+  when the user provides inline feedback about a skill's behavior and wants it
+  applied, or when a grill session, eval run, or audit has produced findings
+  the user wants acted on — even if they don't say "improve" explicitly. Do
+  not use when the user wants a read-only review only — use /skill-audit
+  instead. Do not use when no improvement signals are present in the
+  conversation or referenced files.
+allowed-tools: Bash Read Write Edit
+metadata:
+  category: factory
+---
+
+## Gotchas
+
+- Patching per symptom is the default failure mode. Three eval failures may all trace to one missing instruction — always identify the root cause before editing.
+- Do not create new scripts unless a signal explicitly calls for it. Writing scripts from scratch requires transcript analysis that is out of scope here; flag the opportunity as a suggestion instead.
+- If no improvement signals are present, do not proceed — redirect to `/skill-audit` for a blind review.
+
+## Step 1 — Verify inputs
+
+Confirm:
+- [ ] Skill directory path is provided and the directory exists
+- [ ] At least one improvement signal is present in the conversation or a referenced file
+
+If the skill dir is missing, ask for it. If no signals are present, stop: "This skill applies existing signals to a skill. For a blind review without signals, use `/skill-audit` instead."
+
+Signals can come from anywhere in the conversation or referenced files:
+- Grill session output (most common predecessor in the factory sequence)
+- `/skill-audit` findings (PASS/FAIL/SUGGESTION punch list)
+- Eval assertion failures (grading.json, benchmark.json)
+- Human feedback (feedback.json, inline in conversation, PR or issue comments)
+- Session context describing what went wrong
+
+## Step 2 — Gather and group signals
+
+Read the current skill files (SKILL.md and any files in scripts/, references/, assets/). Then collect all signals from the conversation and any file paths the user has referenced.
+
+Group signals by **root cause**, not symptom. Ask: "What single gap in the skill causes this cluster of failures?" One root cause → one fix. Do not make a separate edit for each symptom.
+
+Example:
+- Eval fails because output format is wrong
+- Audit finding: no output template defined
+- User feedback: "I always have to ask it to format the output"
+- Root cause: SKILL.md has no output format specification → one fix: add an output template
+
+## Step 3 — Announce planned changes
+
+Before editing, state:
+- Which root causes were identified and what evidence supports each
+- Which files will be changed and what will change in each
+
+Then proceed — edits are reversible via git, no approval checkpoint needed.
+
+## Step 4 — Apply changes
+
+Edit any file in the skill directory that the signals point to: SKILL.md, scripts/, references/, assets/, README.md.
+
+**Generalize, don't patch.** Find the underlying gap, not the specific example that failed. A fix scoped only to the test cases you've seen will overfit and perform worse on new inputs.
+
+**Keep it lean.** Remove instructions that aren't pulling their weight. For every sentence you add, ask: "Would the agent get this wrong without it?" A shorter, focused skill consistently outperforms an exhaustive one.
+
+**Explain the why.** Reasoning-based instructions outperform rigid directives. If you find yourself writing a rule in all caps (ALWAYS/NEVER), reframe it: explain why the behavior matters so the agent can apply judgment in edge cases.
+
+**Fix the root, not the symptom.** If a signal points to a script or reference file, edit that file directly rather than adding a workaround in SKILL.md.
+
+**On scripts**: Fix and edit existing scripts freely when signals point to them.
+
+## Step 5 — Validate and close
+
+Run `/skill-audit` on the skill directory. Resolve any FAIL findings before considering the improvement complete.
+
+If the skill has no `evals/` directory, note it after the audit: "No evals found — consider running `/write-eval` to add test coverage so future improvement cycles have quantitative signals to work from."