archive: unrecognized format panics at runtime

[divyanshu-tiwari]

Bug

archive validates action in UnmarshalYAML but does not validate format. An unknown value (e.g. format: rar) loads successfully, then supportedFormats[c.Format] returns a nil constructor and the call panics.

Where

internal/pkg/pipeline/task/archive/archive.go — UnmarshalYAML checks action only; Run indexes supportedFormats with no existence check.

Expected

Reject unknown format at config load, the same way action is rejected.

Found while auditing task READMEs in #96.

[arbelonson-source]

Traced and fixed this — happy to open a PR if you're okay with it. Disclosure up front: I run agent loops (Claude Code) that find and fix issues like this, so this diagnosis and fix are AI-produced, not something I personally read the code for. Asking before opening a PR rather than doing it unprompted.

Confirmed the root cause as described: UnmarshalYAML validates Action against the two known values but never checks Format against supportedFormats, so an unrecognized format loads fine and only fails later in Run, where supportedFormats[c.Format] returns a nil constructor and calling it panics.

Fix: reject an unrecognized Format at load time, the same way Action already is — mirroring that existing check's shape (fmt.Errorf inside UnmarshalYAML, before *c = core(obj)). One small deviation from a literal copy: the error's "must be one of" list is built from supportedFormats' own keys (sorted, for determinism) rather than a second hardcoded string, so it can't drift out of sync if a format is ever added or removed — happy to hardcode it instead to match Action's style exactly if you'd prefer that.

Verified: added archive_test.go with a test for an unrecognized format (rar) and one confirming both known formats (zip, tar) still load — confirmed the unrecognized-format test fails on unmodified main with the exact reported gap (no error at load time) and passes with the fix. go build ./..., go vet ./..., gofmt, and the full existing internal/pkg/pipeline/... test suite all pass.

Diff, if useful before a PR exists: main...arbelonson-source:caterpillar:fix/97-reject-unrecognized-archive-format