agent-file-synchronization
Identity
You synchronize project instruction files across modern AI tooling environments.
Today, AGENTS.md is an open cross-tool standard (Codex, Cursor, Antigravity, and portable agents),
while CLAUDE.md is used by Claude Code, GEMINI.md is used by Gemini CLI, and
.github/copilot-instructions.md is used by GitHub Copilot.
A blind full-copy destroys platform-specific sections; this skill detects and re-preserves those
sections automatically instead of requiring a human to re-append them by hand. It also respects
repos that only want a subset of target files (via --targets) rather than forcing all 4 formats.
Scope: This skill owns mechanical replication. It does not own content quality
(optimize-agent-instructions) or initial project scaffolding (project-setup).
What gets preserved per target
| Target |
Preserved section |
Detected via |
GEMINI.md |
## Gemini CLI Tool Mapping table, appended at end of file |
Tail marker match |
.github/copilot-instructions.md |
# Copilot Instructions for <repo> header + authoritative blockquote |
Header lines before the shared body's first line |
AGENTS.md |
Open cross-tool standard (preserves custom header lines before anchor if any) |
Header lines before anchor |
CLAUDE.md |
Anthropic Claude Code standard |
Header lines before anchor |
The shared body boundary is the fixed anchor line: "Behavioral guidelines to reduce
common LLM coding mistakes. Merge with project-specific instructions as needed." (or standard # Project Name / # Purpose anchors).
Steps
Dry-run first, always:
python3 ./scripts/sync_instruction_files.py --dry-run
Or with selective source and targets:
python3 ./scripts/sync_instruction_files.py --source AGENTS.md --targets GEMINI.md,CLAUDE.md --dry-run
Reports per-target line-count deltas and preserved sections.
If the dry-run summary looks right, execute:
python3 ./scripts/sync_instruction_files.py --execute
Verify — inspect target files (e.g. tail -20 GEMINI.md) to confirm preserved sections.
Reinstall + audit per this repo's standing rules — sync only touches root-level docs,
not plugins/ source, so no plugin reinstall is needed for this step. But if the CLAUDE.md
edit that triggered the sync also touched a skill/script, reinstall that plugin separately.
Checking .agent/rules/ drift against plugin rule sources
.agent/rules/*.md and plugins/<plugin>/rules/*.md are a separate pairing from the
CLAUDE.md-family mirrors above — same filename, but drift direction isn't reliably one-way
(either side can be the one that's stale), so this mode never writes:
python3 ./scripts/sync_instruction_files.py --check-rules
Reports per rule file: IDENTICAL, DIFFERS (with a unified diff), or
NO PLUGIN COUNTERPART FOUND (a .agent/rules/-only file with no matching plugin source —
not necessarily a problem, just worth knowing). On DIFFERS, read both files and manually
apply the fix on whichever side is actually behind — do not assume the plugin copy always wins.
Common Failures
- New platform section added to CLAUDE.md's own required structure: if a future target needs
a new kind of preserved section (not a header-before-anchor or tail-after-marker), the script's
TARGETS list and marker-detection logic need a code change — this skill does not invent new
preservation strategies on its own.
- Anchor line changed or removed from CLAUDE.md: the script hard-fails rather than guessing at
the body boundary — if this happens, check whether CLAUDE.md's opening line changed and update
ANCHOR_LINE in scripts/sync_instruction_files.py to match.
- Target file has stray content between title and header that isn't actually platform-specific:
the script will treat it as preserved-header and keep re-appending it forever. Manually clean the
target once; subsequent syncs will then preserve the cleaned version correctly.
References
acceptance-criteria.mdCLAUDE.md — "Instruction File Mirrors" section documents the same preservation rules this skill automatesoptimize-agent-instructions (agent-agentic-os) — deep content-quality audit, complementary not overlapping
1---2name: agent-file-synchronization3description: Synchronizes project instruction files across AGENTS.md, CLAUDE.md, GEMINI.md, and .github/copilot-instructions.md while preserving platform-specific sections (GEMINI.md tool mapping, copilot authoritative header). Supports AGENTS.md or CLAUDE.md as primary source, and selective target syncing. Also reports drift between .agent/rules/ and matching plugins/*/rules/ sources. Triggers: "sync instructions", "sync CLAUDE.md to GEMINI.md", "sync AGENTS.md", "replicate instruction files", "mirror CLAUDE.md", "check rule drift".4---56<example>7<commentary>User has edited instructions and wants specific agent files kept in sync.</commentary>8user: "sync instructions across my agent files"9assistant: [triggers agent-file-synchronization, runs sync_instruction_files.py --dry-run by default, reports the diff summary, then runs with --execute after user confirmation]10</example>1112<example>13<commentary>User only uses AGENTS.md and GEMINI.md and wants selective target sync.</commentary>14user: "sync AGENTS.md to GEMINI.md"15assistant: [triggers agent-file-synchronization, runs sync_instruction_files.py --source AGENTS.md --targets GEMINI.md --dry-run]16</example>1718<example>19<commentary>Negative — user wants a stylistic quality audit, not a mechanical sync.</commentary>20user: "audit my AGENTS.md against Karpathy's principles and rewrite it"21assistant: [triggers optimize-agent-instructions, not agent-file-synchronization — that skill owns content quality, this one owns mechanical replication]22</example>2324# agent-file-synchronization2526## Identity2728You synchronize project instruction files across modern AI tooling environments.29Today, **AGENTS.md** is an open cross-tool standard (Codex, Cursor, Antigravity, and portable agents),30while **CLAUDE.md** is used by Claude Code, **GEMINI.md** is used by Gemini CLI, and31**.github/copilot-instructions.md** is used by GitHub Copilot.3233A blind full-copy destroys platform-specific sections; this skill detects and re-preserves those34sections automatically instead of requiring a human to re-append them by hand. It also respects35repos that only want a subset of target files (via `--targets`) rather than forcing all 4 formats.3637**Scope**: This skill owns *mechanical replication*. It does not own *content quality*38(`optimize-agent-instructions`) or *initial project scaffolding* (`project-setup`).3940## What gets preserved per target4142| Target | Preserved section | Detected via |43|---|---|---|44| `GEMINI.md` | `## Gemini CLI Tool Mapping` table, appended at end of file | Tail marker match |45| `.github/copilot-instructions.md` | `# Copilot Instructions for <repo>` header + authoritative blockquote | Header lines before the shared body's first line |46| `AGENTS.md` | Open cross-tool standard (preserves custom header lines before anchor if any) | Header lines before anchor |47| `CLAUDE.md` | Anthropic Claude Code standard | Header lines before anchor |4849The shared body boundary is the fixed anchor line: *"Behavioral guidelines to reduce50common LLM coding mistakes. Merge with project-specific instructions as needed."* (or standard `# Project Name` / `# Purpose` anchors).5152## Steps53541. **Dry-run first, always**:55 ```bash56 python3 ./scripts/sync_instruction_files.py --dry-run57 ```58 Or with selective source and targets:59 ```bash60 python3 ./scripts/sync_instruction_files.py --source AGENTS.md --targets GEMINI.md,CLAUDE.md --dry-run61 ```62 Reports per-target line-count deltas and preserved sections.63642. **If the dry-run summary looks right, execute**:65 ```bash66 python3 ./scripts/sync_instruction_files.py --execute67 ```68693. **Verify** — inspect target files (e.g. `tail -20 GEMINI.md`) to confirm preserved sections.70714. **Reinstall + audit** per this repo's standing rules — sync only touches root-level docs,72 not `plugins/` source, so no plugin reinstall is needed for *this* step. But if the CLAUDE.md73 edit that triggered the sync also touched a skill/script, reinstall that plugin separately.7475## Checking `.agent/rules/` drift against plugin rule sources7677`.agent/rules/*.md` and `plugins/<plugin>/rules/*.md` are a **separate pairing** from the78CLAUDE.md-family mirrors above — same filename, but drift direction isn't reliably one-way79(either side can be the one that's stale), so this mode never writes:8081```bash82python3 ./scripts/sync_instruction_files.py --check-rules83```8485Reports per rule file: `IDENTICAL`, `DIFFERS` (with a unified diff), or86`NO PLUGIN COUNTERPART FOUND` (a `.agent/rules/`-only file with no matching plugin source —87not necessarily a problem, just worth knowing). On `DIFFERS`, read both files and manually88apply the fix on whichever side is actually behind — do not assume the plugin copy always wins.8990## Common Failures9192- **New platform section added to CLAUDE.md's own required structure**: if a future target needs93 a *new* kind of preserved section (not a header-before-anchor or tail-after-marker), the script's94 `TARGETS` list and marker-detection logic need a code change — this skill does not invent new95 preservation strategies on its own.96- **Anchor line changed or removed from CLAUDE.md**: the script hard-fails rather than guessing at97 the body boundary — if this happens, check whether CLAUDE.md's opening line changed and update98 `ANCHOR_LINE` in `scripts/sync_instruction_files.py` to match.99- **Target file has stray content between title and header that isn't actually platform-specific**:100 the script will treat it as preserved-header and keep re-appending it forever. Manually clean the101 target once; subsequent syncs will then preserve the cleaned version correctly.102103## References104105- [`acceptance-criteria.md`](references/acceptance-criteria.md)106- `CLAUDE.md` — "Instruction File Mirrors" section documents the same preservation rules this skill automates107- `optimize-agent-instructions` (agent-agentic-os) — deep content-quality audit, complementary not overlapping
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