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Collapse¶

When chaining multiple upgrades, the collapse engine merges redundant operations into a minimal set.

Function¶

`collapse_operations(operations) → list[AnyOperation]`¶

Takes a flat list of operations (from all upgrade steps) and returns a collapsed list.

from bluefox_upgrade import collapse_operations

collapsed = collapse_operations(all_ops)

Collapse rules¶

File operations¶

Scenario	Result
Multiple `ReplaceFile` on same path	Keep last
`CreateFile` then `ReplaceFile` on same path	Keep `CreateFile` with last template
`ReplaceFile` then `RemoveFile` on same path	Keep `RemoveFile`
`CreateFile` then `RemoveFile` on same path	Both removed (no-op)

Section operations¶

Scenario	Result
Multiple `UpdateSection` on same path + marker	Keep last

Dependency operations¶

Scenario	Result
Multiple `BumpDependency` on same package	Merge: first `old_spec` → last `new_spec`
`AddDependency` then `BumpDependency` on same package	`AddDependency` with final `new_spec`
`AddDependency` then `RemoveDependency` on same package	Both removed (no-op)

Example¶

Three upgrades with redundant Dockerfile replacements:

ops = [
    ReplaceFile(path="Dockerfile", template="v2.jinja", description="v2"),
    BumpDependency(name="fastapi", old_spec=">=0.115", new_spec=">=0.118"),
    ReplaceFile(path="Dockerfile", template="v3.jinja", description="v3"),
    BumpDependency(name="fastapi", old_spec=">=0.118", new_spec=">=0.120"),
]

collapsed = collapse_operations(ops)
# Result: [
#   ReplaceFile(path="Dockerfile", template="v3.jinja", ...),
#   BumpDependency(name="fastapi", old_spec=">=0.115", new_spec=">=0.120"),
# ]