Use --filter=blob:none only in promisor repos, shallow fetch otherwise

[pjbgf]

Checkpoint fetches previously always used --filter=blob:none, which turns non-promisor repositories into promisor-enabled ones as a side effect. Now we detect whether the repo is already a partial clone (via extensions.partialClone config) and only use treeless fetches in that case. Non-promisor repos use --depth=1 (shallow) instead, or plain fetches where full history is needed for rebase/merge.

---

Note

Medium Risk
Changes git fetch flags across checkpoint metadata read/push paths based on detected repo type, which can affect how much history/blobs are available and could impact resume/sync behavior in edge cases.

Overview
Stops unconditionally using --filter=blob:none for checkpoint-related fetches so non-partial-clone repos don’t get converted into promisor repos as a side effect.

Adds promisor detection via git config --local extensions.partialClone (cached per process) and centralizes flag selection in PartialCloneFilterArgs*; metadata/v2 fetches now use treeless fetches only for promisor repos and otherwise prefer shallow (--depth=1) or unfiltered fetches where full history is required for rebase/merge.

Updates both origin fetches and checkpoint-remote URL fetches, and adds unit tests covering promisor detection, context-cancellation behavior, and the chosen fetch arguments.

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[Copilot]

Pull request overview

Updates checkpoint fetch behavior to avoid unintentionally converting non-partial-clone repositories into promisor (partial clone) repositories. This aligns fetch flags with the repo’s existing configuration by detecting whether the repo is already promisor-enabled and choosing --filter=blob:none only in that case, otherwise using shallow or full fetches as appropriate.

Changes:

• Add promisor (partial-clone) detection and helper functions to select appropriate git fetch arguments.
• Update multiple fetch call sites to conditionally use --filter=blob:none only for promisor repos, and shallow fetch otherwise.
• Add unit tests covering promisor detection and argument selection helpers.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
cmd/entire/cli/strategy/common.go	Adds promisor detection + cached result and helper functions to build fetch args.
cmd/entire/cli/strategy/common_test.go	Adds tests for promisor detection and fetch-arg helper behavior.
cmd/entire/cli/strategy/push_v2.go	Adjusts fetch logic during push conflict recovery to only use blob filtering in promisor repos.
cmd/entire/cli/strategy/push_common.go	Adjusts fetch logic for session rebase to only use blob filtering in promisor repos.
cmd/entire/cli/strategy/checkpoint_remote.go	Uses new helper to choose fetch flags when fetching from checkpoint remote URLs.
cmd/entire/cli/git_operations.go	Switches metadata/v2 fetch helpers to use the new conditional fetch-arg helpers.

[pjbgf]

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[cursor]

Error messages say "treeless" for shallow fetches

Low Severity

FetchMetadataTreeOnly and FetchV2MainTreeOnly now perform a shallow fetch (--depth=1, no --filter) for non-promisor repos, but the error messages still unconditionally say "treeless fetch timed out" and "failed to treeless-fetch". These messages were accurate before this PR (when --filter=blob:none was always used) but are now misleading for the non-promisor code path, which could confuse debugging.

Additional Locations (1)

• cmd/entire/cli/git_operations.go#L476-L479

 

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[pjbgf]

Closing in favour of #934.