Improvement Executor

Applies accepted candidates with automatic backup and rollback.

When to Use

把已批准的改进候选应用到目标文件
回滚之前的变更（通过 receipt）
用 --dry-run 预览变更

When NOT to Use

给候选打分 → use improvement-discriminator
门禁验证 → use improvement-gate
全流程编排 → use improvement-orchestrator

CLI

# Apply a candidate (requires ranking artifact + candidate ID)
python3 scripts/execute.py \
  --input ranking.json \           # REQUIRED: ranking artifact from discriminator
  --candidate-id cand-01-docs \    # REQUIRED: which candidate to execute
  --state-root /path/to/state \    # default: lib/state_machine.DEFAULT_STATE_ROOT
  --output result.json \           # default: {state-root}/executions/{run-id}-{candidate-id}.json
  --force                          # execute even if recommendation != accept_for_execution

# Rollback a previous change
python3 scripts/rollback.py --receipt receipt.json [--dry-run]

Param	Default	When to change
`--input`	(required)	Always: path to ranking artifact JSON from discriminator
`--candidate-id`	(required)	Always: the `id` field of the candidate to execute
`--force`	false	Use to execute candidates with recommendation=hold (bypasses critic check)
`--output`	auto	Set for custom output location

4 Action Types

Action	Trigger	Behavior
`append_markdown_section`	`execution_plan.action`	Appends heading + bulleted content lines at EOF. No-op if heading already exists
`replace_markdown_section`	`execution_plan.action`	Finds section by heading match, replaces all lines until next same-or-higher-level heading
`insert_before_section`	`execution_plan.action`	Inserts content lines before a matched heading
`update_yaml_frontmatter`	`execution_plan.action`	Merges `frontmatter_updates` dict into YAML frontmatter (requires PyYAML)

Backup Mechanism

Every execution creates a backup at {state-root}/executions/backups/{run-id}/{candidate-id}-{filename} BEFORE modifying the target. The backup path is stored in result.rollback_pointer.backup_path for gate-driven rollback.

Safety Guards

Recommendation check: refuses to execute if recommendation != accept_for_execution (use --force to override)
Category check: only EXECUTOR_SUPPORTED_CATEGORIES (docs, reference, guardrail) are auto-executable; others return status=unsupported
File existence: target file must exist, otherwise SystemExit
Execution trace: every run captures a structured execution_trace dict with action, status, diff_summary for GEPA feedback loop

<example> 正确: 执行一个 docs 类候选 $ python3 scripts/execute.py --input ranking.json --candidate-id cand-01-docs --state-root ./state → Backup: ./state/executions/backups/run001/cand-01-docs-README.md → Appended "## Operator Notes" section → stdout: ./state/executions/run001-cand-01-docs.json </example> <anti-example> 错误: 跳过 discriminator 直接执行 medium-risk candidate $ python3 scripts/execute.py --input ranking.json --candidate-id cand-04-prompt --force → category=prompt 不在 EXECUTOR_SUPPORTED_CATEGORIES → status=unsupported → medium/high risk 必须经 gate 走 pending_promote → 人工审批 </anti-example>

Output Artifact

{"stage": "executed", "status": "success", "candidate_id": "cand-01-docs",
 "result": {"status": "success", "modified": true, "diff": "--- a/...",
   "backup_path": "...", "rollback_pointer": {"method": "restore_backup_file",
     "backup_path": "...", "target_path": "..."}},
 "execution_trace": {"type": "execution_trace", "action": "append_markdown_section", ...},
 "next_step": "apply_gate", "next_owner": "gate"}

Related Skills

improvement-discriminator: Scores candidates → executor only runs accept_for_execution ones
improvement-gate: Validates execution results → may trigger rollback via rollback_pointer
improvement-orchestrator: Calls executor as stage 4, passes ranking artifact + candidate ID