Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/openhands/extensions/migration-mappingnpx skills add OpenHands/extensions --skill migration-mappinggit clone --depth 1 https://github.com/OpenHands/extensionsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00028 | $0.00520 |
| Opus 5 | $0.00014 | $0.00260 |
| Sonnet 5 | $0.00006 | $0.00104 |
| Haiku 4.5 | $0.00003 | $0.00052 |
Grade A, and why
migration-mapping scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Create a mapping from source language files (e.g., COBOL) to target language files (e.g., Java) to document which target files implement the functionality of each source file.
Task
Examine all source language files and identify the corresponding target language files that implement the same functionality. This mapping is essential for:
- Migration quality evaluation
- Traceability documentation
- Gap analysis
Output Format
Save the mapping as a JSON file with this structure:
{
"source_file_1.cbl": ["target_file_a.java", "target_file_b.java"],
"source_file_2.cbl": ["target_file_c.java"],
"source_file_3.cbl": []
}
Rules
- Many-to-many mapping: A source file may map to multiple target files, and a target file may implement logic from multiple source files
- Complete coverage: EVERY source file must appear as a key in the mapping
- Complete target coverage: EVERY target file should appear as a value at least once
- Empty arrays: If a source file has no corresponding target implementation, use an empty array
[] - Incremental: If a mapping file already exists, update it rather than replacing it
How to Identify Mappings
Look for:
- Matching class/program names
- Similar function/paragraph names
- Matching business logic patterns
- Comments referencing source files
- Import/include statements
- Data structure similarities
Example
For a COBOL-to-Java migration:
{
"CALC001.cbl": ["InvoiceCalculator.java", "TaxCalculator.java"],
"CUST002.cbl": ["CustomerService.java", "CustomerRepository.java"],
"UTIL003.cbl": ["StringUtils.java"],
"SCREEN001.cbl": []
}
Note: SCREEN001.cbl maps to nothing because UI code was not migrated.
Verification
After creating the mapping:
- Every source file is a key
- No duplicate keys
- Target files are relative paths from project root
- JSON is valid and well-formatted
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 73 lines · 28 tokens per session scan A 6b65c7e6b155
migration-mapping is a skill published in the GitHub repository OpenHands/extensions (137 stars, last pushed 4d ago), licensed MIT. It adds 28 tokens to every session and 520 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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