MGS3031: a declaration claim nothing can grade

magus job fork, the client tool (magus\job.put) and a magusfile's magus\job.put refused a job because one of its write paths or deny paths names a declaration (<file>#<declaration>) that no footprint could ever check. For a write path:

[MGS3031] job: wave/notes claims a declaration no footprint can grade:
  "notes.txt" has no diff driver, so no changed line of it can be placed in a
  declaration; give `*.txt` one in .gitattributes (`magus doctor` lists the
  managed ones). Claim the whole file instead, or fix what is named

For a deny path, the refusal names the field:

[MGS3031] job: wave/notes claims a declaration no footprint can grade:
  deny path "notes.txt" has no diff driver, so no changed line of it can be
  placed in a declaration; give `*.txt` one in .gitattributes (`magus doctor`
  lists the managed ones). Claim the whole file instead, or fix what is named

Nothing was written to the job store. A put that adds such a path to a job that already exists is refused the same way and leaves the job as it was.

Why

A claim like run.go#executeStages lets two jobs start on one file. It holds only because magus can say, from the job's diff, which declaration every changed line lands in. That placement is git's: the file's diff driver (the diff= attribute) names the declaration each line sits under. A claim on a file with no driver, on a pattern, or in a checkout whose version control places no lines would read as a boundary and check nothing, so it is refused rather than recorded.

A deny path such as run.go#executeStages is placed the same way: the guard and magus job wait refuse only a change inside that declaration. One magus cannot place would deny the whole file while the job says one declaration, so the same rules refuse it.

What is refused

Each of these, in a write path or a deny path:

• An empty declaration: run.go#.
• A pattern: internal/*.go#Run. A declaration lives in one file.
• A file with no diff driver: magus manages drivers for Go, Python, Rust, Markdown, TypeScript and Buzz in its .gitattributes block. Any other extension needs a *.<ext> diff=<driver> line of your own.
• A checkout with no version control, or one that does not place changed lines. Only git does today.
• A path that contains #, spelled bare: notes/a#b.md when that file exists reads both as the path and as a claim on notes/a. Spell the path ./notes/a#b.md or notes/a\#b.md; the escaped form also takes a claim, notes/a\#b.md#Intro.

What to do

Claim the whole file, which is what the job was going to be graded against anyway:

magus job fork wave/notes --write-paths notes.txt

For a deny path, deny the whole file, or leave it out:

magus job fork wave/notes --write-paths src/run.go --deny-paths notes.txt

Or give the extension a driver, then fork again with the declaration.

See also

• Leases: write paths, claims, and what the guard enforces.
• MGS3018: a directory as a job write path.