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decant: Skill for Claude Code

.claude/skills/schema-migration/SKILL.md

schema-migration is a skill for Claude Code from dosu-ai/decant. It costs 60 tokens per session (505 once invoked), scanned A, original, Apache-2.0.

A set of instructions for changing Decant's SQLite database structure or rebuilding stored archives. SQLite is a file-based database; the instructions cover tables, columns, indexes, triggers, and data re-derivation.

In plain words
What is it for?
Use it when changing database migrations, the fresh-database schema, schema versioning, or the revision that causes existing source files to be processed again.
Why use it?
It helps prevent old archives and new archives from ending up with different structures or incomplete upgrades. It also prevents accidental edits to migrations that have already been used.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions AGENTS.md.

This is dosu-ai/decant's own configuration. It tells Claude Code how to work on decant itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything decant configures →

not rated 72repo +2 today A scan 60 tokens original Apache-2.0
View source ↗ dosu-ai/decant dosu.dev
Reuse

Borrowing it

Nothing to install: this file belongs to dosu-ai/decant. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/dosu-ai/decant/main/.claude/skills/schema-migration/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/dosu-ai/decant

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for schema-migration

README.md
[![agentmods](https://agentmods.dev/badge/skills/dosu-ai/decant/schema-migration/github.svg)](https://agentmods.dev/skills/dosu-ai/decant/schema-migration)
Your own site
<a href="https://agentmods.dev/skills/dosu-ai/decant/schema-migration"><img src="https://agentmods.dev/badge/skills/dosu-ai/decant/schema-migration/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for schema-migration

Your own site · 80×15
<a href="https://agentmods.dev/skills/dosu-ai/decant/schema-migration"><img src="https://agentmods.dev/badge/skills/dosu-ai/decant/schema-migration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 505 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00060 $0.00505
Opus 5.5 $0.00024 $0.00202
Sonnet 5.5 $0.00012 $0.00101
Haiku 4.5 $0.00006 $0.00051

Measured 28d ago against content hash 88ef141d166f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

schema-migration 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 28d 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.

.claude/skills/schema-migration/SKILL.md · 43 lines

What it actually says

Schema migration

The rules are AGENTS.md invariant 5 and the "Rebuilds and migrations" section of docs/data-lifecycle.md. Read both before editing.

Rules

  • A migration is frozen once it is committed, because someone may already have opened an archive with that branch. Never edit an existing if (current < N) block, on main or on a feature branch; add a new one, even to fix a mistake in the previous one.
  • Bump LATEST_SCHEMA_VERSION in src/db.ts. Refer to that constant in docs instead of writing the number.
  • Guard each statement so a partially-migrated or operator-modified archive still converges (IF NOT EXISTS, hasTable, hasColumn), and stamp the new version in schema_migrations inside the same block.
  • src/schema.sql is the effective baseline for a fresh archive. Apply the same change there so a fresh archive and a migrated one produce the same buildSchemaManifest fingerprint; src/schema-manifest.ts changes only if the manifest needs to learn a new object kind.
  • Bump INGEST_PIPELINE_REVISION in src/ingest.ts only when unchanged source files must be re-derived. The next sync then backfills them once and later syncs stay idempotent. A pure index or constraint change does not need it.
  • Unsupported older archives are rebuild-only; do not add upgrade paths below the baseline.

Tests

  • test/db.test.ts: migrate a previous-version archive and compare it with a fresh one; assert any query plan the new index exists for.
  • Run the migration against a scratch copy of a large archive and time it (DECANT_DB=<copy>). Never point a migration at ~/.decant/decant.db.

Docs

Update docs/data-lifecycle.md when archive state, sync, or migration behavior changes, and docs/architecture.md if module boundaries move.

Changes

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.

  1. 28d ago First seen · 43 lines · 60 tokens per session scan A 88ef141d166f

Subscribe to this mod's changes

schema-migration is a skill published in the GitHub repository dosu-ai/decant (72 stars, last pushed today), licensed Apache-2.0. It adds 60 tokens to every session and 505 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-30.

Claude CodeDatabasesagent-observabilityclicodexcoding-agentsdeveloper-tools
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