feat: self-improving skills loop — observe, inspect, amend, evaluate

- Add skill health observation layer (execution logging, success/failure tracking)
- Add skill health inspector (trace recurring failures across runs)
- Add amendify mechanism (propose SKILL.md patches from failure evidence)
- Add evaluation scaffolding (compare amended vs original performance)
- Wire into session-inspect CLI: skills:health, skills:amendify, skills:evaluate
- 1145/1145 tests passing (+3 new)

scripts/lib/skill-improvement/health.js

@@ -0,0 +1,118 @@
+'use strict';
+
+const HEALTH_SCHEMA_VERSION = 'ecc.skill-health.v1';
+
+function roundRate(value) {
+  return Math.round(value * 1000) / 1000;
+}
+
+function rankCounts(values) {
+  return Array.from(values.entries())
+    .map(([value, count]) => ({ value, count }))
+    .sort((left, right) => right.count - left.count || left.value.localeCompare(right.value));
+}
+
+function summarizeVariantRuns(records) {
+  return records.reduce((accumulator, record) => {
+    const key = record.run && record.run.variant ? record.run.variant : 'baseline';
+    if (!accumulator[key]) {
+      accumulator[key] = { runs: 0, successes: 0, failures: 0 };
+    }
+
+    accumulator[key].runs += 1;
+    if (record.outcome && record.outcome.success) {
+      accumulator[key].successes += 1;
+    } else {
+      accumulator[key].failures += 1;
+    }
+
+    return accumulator;
+  }, {});
+}
+
+function deriveSkillStatus(skillSummary, options = {}) {
+  const minFailureCount = options.minFailureCount || 2;
+  if (skillSummary.failures >= minFailureCount) {
+    return 'failing';
+  }
+
+  if (skillSummary.failures > 0) {
+    return 'watch';
+  }
+
+  return 'healthy';
+}
+
+function buildSkillHealthReport(records, options = {}) {
+  const filterSkillId = options.skillId || null;
+  const filtered = filterSkillId
+    ? records.filter(record => record.skill && record.skill.id === filterSkillId)
+    : records.slice();
+
+  const grouped = filtered.reduce((accumulator, record) => {
+    const skillId = record.skill.id;
+    if (!accumulator.has(skillId)) {
+      accumulator.set(skillId, []);
+    }
+    accumulator.get(skillId).push(record);
+    return accumulator;
+  }, new Map());
+
+  const skills = Array.from(grouped.entries())
+    .map(([skillId, skillRecords]) => {
+      const successes = skillRecords.filter(record => record.outcome && record.outcome.success).length;
+      const failures = skillRecords.length - successes;
+      const recurringErrors = new Map();
+      const recurringTasks = new Map();
+      const recurringFeedback = new Map();
+
+      skillRecords.forEach(record => {
+        if (!record.outcome || record.outcome.success) {
+          return;
+        }
+
+        if (record.outcome.error) {
+          recurringErrors.set(record.outcome.error, (recurringErrors.get(record.outcome.error) || 0) + 1);
+        }
+        if (record.task) {
+          recurringTasks.set(record.task, (recurringTasks.get(record.task) || 0) + 1);
+        }
+        if (record.outcome.feedback) {
+          recurringFeedback.set(record.outcome.feedback, (recurringFeedback.get(record.outcome.feedback) || 0) + 1);
+        }
+      });
+
+      const summary = {
+        skill: {
+          id: skillId,
+          path: skillRecords[0].skill.path || null
+        },
+        totalRuns: skillRecords.length,
+        successes,
+        failures,
+        successRate: skillRecords.length > 0 ? roundRate(successes / skillRecords.length) : 0,
+        status: 'healthy',
+        recurringErrors: rankCounts(recurringErrors).map(entry => ({ error: entry.value, count: entry.count })),
+        recurringTasks: rankCounts(recurringTasks).map(entry => ({ task: entry.value, count: entry.count })),
+        recurringFeedback: rankCounts(recurringFeedback).map(entry => ({ feedback: entry.value, count: entry.count })),
+        variants: summarizeVariantRuns(skillRecords)
+      };
+
+      summary.status = deriveSkillStatus(summary, options);
+      return summary;
+    })
+    .sort((left, right) => right.failures - left.failures || left.skill.id.localeCompare(right.skill.id));
+
+  return {
+    schemaVersion: HEALTH_SCHEMA_VERSION,
+    generatedAt: new Date().toISOString(),
+    totalObservations: filtered.length,
+    skillCount: skills.length,
+    skills
+  };
+}
+
+module.exports = {
+  HEALTH_SCHEMA_VERSION,
+  buildSkillHealthReport
+};