fix(migrate): skip staging when window is exactly the pending next migration#503
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When `[migrations].next` is set or `check-limit`/`build-limit` trims the chain, mops stages the active chain into `.migrations-<canister>/` and passes that directory to moc. Diagnostics for chain files therefore reference the staged path (e.g. `.migrations-backend/2025...AddEmail.mo`) rather than the original `migrations/...` path. Editor jump-to-error still works because the staged files are symlinks, but the path in raw error text was a recurring source of confusion. Document this in the mops.toml reference, the `mops migrate` page, and the mops-cli skill, and add a snapshot test that pins the current behavior so a future fix (e.g. rewriting paths in moc stderr) is an intentional snapshot update. Made-with: Cursor
Editor jump-to-error does not work on the printed path: the staged directory is removed in a `finally` block before the process exits, so by the time the user reads the error, the file is gone. Tell users to open the same filename under `chain` (or `next` for the pending migration) instead. Made-with: Cursor
…gration The staged migration directory only ever existed because moc takes a single `--enhanced-migration=<dir>` and we sometimes need to merge files from `chain/` and `next-migration/`. When the active window is exactly one file from `next-migration/` (the common dev-loop case `check-limit = 1` with a pending next, or no frozen chain yet), there is no merge to do — moc can be pointed at `next-migration/` directly. Errors then reference the real path the user is editing instead of a staged copy that gets `rm -rf`-ed before the user reads the message. Refactored `prepareMigrationArgs` to fold the previous early-return (no staging) and the new shortcut into a single `realDir` decision, removing duplicated arg-building. Same behavior for every other trimming/staging case. Updated docs and CHANGELOG; added a snapshot test that pins the real-path behavior. Made-with: Cursor
Kamirus
changed the title
…rtcut Revert the structural refactor of `prepareMigrationArgs` from the previous commit; the only behavior change needed is a single early- return branch for "moc only needs the pending next migration". Net change in migrations.ts is now +10/-0 instead of churning the existing shape. Also align the three doc locations with the changelog (both `check-limit = 1 with pending next` and `no frozen chain yet` trigger the shortcut), and add a snapshot test for the empty-chain branch so that case is pinned, not just structurally implied. Made-with: Cursor
Made-with: Cursor
Made-with: Cursor
Made-with: Cursor
Made-with: Cursor
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Problem
When
[canisters.<name>.migrations]triggers staging (a pendingnextmigration, orcheck-limit/build-limittrimming the chain), mops creates a temp.migrations-<canister>/directory of symlinks and points moc at it. Errors look like:The staged dir is
rm -rf-ed in afinallybefore the process exits, so by the time the user reads the error the path no longer resolves — editor jump-to-error fails, and CI logs contain a path that looks like an internal artifact.Why staging exists
moc --enhanced-migrationtakes a single directory. When the active window straddleschain/andnext-migration/, or when trimming hides files insidechain/, mops needs a synthesized directory holding exactly the files moc should see.Fix
When moc only needs the pending
nextmigration — empty chain, orcheck-limit = 1with a pending next — there's nothing to merge. Point moc atnext-migration/directly:Before:
After:
This covers the common dev-loop case (writing a new migration with
check-limit = 1) and the first-migration case (no frozen chain yet). Every other trimming / merge case still stages — diagnostics there continue to print the.migrations-backend/...path.Test plan
check-limit=1 with pending next reports real next-migration path on error— pins the trimmed-to-1 branchempty chain with pending next reports real next-migration path on error— pins the empty-chain brancherror inside a chain migration reports its file location— pins the staged-path behavior for the cases that still stagenpm test -- --testPathPatterns=migrate.test.ts— 19/19 passnpm run check— cleanbuild.test.tsfailures verified unrelated (stash + retest onmain)