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/hellotern/sextant/migratenpx skills add hellotern/Sextant --skill migrategit clone --depth 1 https://github.com/hellotern/SextantWhat 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 | $0.00109 | $0.01941 |
| Opus 5 | $0.00055 | $0.00971 |
| Sonnet 5 | $0.00022 | $0.00388 |
| Haiku 4.5 | $0.00011 | $0.00194 |
Grade A, and why
migrate 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.
How it starts
The opening of the file, as written. The whole thing — 199 lines — stays where its author put it; the contents beside it link to each section on GitHub.
!../principles/SKILL_BODY.md
!../tool-gitnexus/SKILL_BODY.md
Migration Workflow
Core Principle
Migrations are multi-module, stateful, and partially irreversible. The core strategy is migrate in dependency order, validate at every checkpoint, and keep rollback options open until all modules are confirmed working.
Distinct from sextant:modify-feature: Modify-feature changes one module's behavior. Migration coordinates changes across many modules in a defined sequence, with compatibility shims and a rollback plan at each phase boundary.
Complete Execution Workflow
Progress tracking: At the start of each step, output an updated progress block so the user knows where the migration stands.
Migration Progress ✓ Step 1: Scope Scan — <N files identified, Tier N impact> ✓ Step 2: Compatibility — <N hard-cutover steps flagged> → Step 3: Migration Plan — in progress ○ Step 4: Per-Module Migration + Validation ○ Step 5: CleanupReplace
○with→for the current step, and✓once complete.
Step 1: Migration Scope Scan
Enumerate all affected files and produce a migration inventory:
- List every file that references the old API, type, pattern, or version
- Score the total impact using the Impact Radius Scorecard (§3.2)
- Identify dependency relationships between affected files
─── Migration Inventory ─────────────────────────────
Migration: <from X> → <to Y>
Impact radius score: N → <Tier>
File | Change Type | Dependency Order
───────────────────────|─────────────────────────|──────────────────────
<file A> | <API call → new API> | leaf (migrate first)
<file B> | <type annotation> | depends on A
<file C> | <core module> | migrate last
─────────────────────────────────────────────────────
🔗 When GitNexus is available, use impact MCP tool to enumerate all dependents automatically.
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 · 199 lines · 109 tokens per session scan A 2e28b6f308df
migrate is a skill published in the GitHub repository hellotern/Sextant (15 stars, last pushed 4mo ago), licensed MIT. It adds 109 tokens to every session and 1,941 once invoked, about $0.0005 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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