Checkpoints V2: Support compact format for Copilot CLI

[computermode]

Adds support for checkpoint V2's compact transcript.jsonl file format for Copilot CLI - the same process as for other agents (ie. #819, #852)

Converts full.jsonl files to the compact, unified transcript.jsonl format to save on space + parsing logic for downstream clients. This is to support future checkpoints V2 work.

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Note

Medium Risk
Adds a new transcript format detector and converter that changes how Compact routes inputs, so mis-detection or edge-case parsing could alter output for some JSONL transcripts. Scope is limited to transcript normalization logic with fixture coverage.

Overview
Adds Copilot CLI events.jsonl support to the transcript compactor, detecting Copilot entries (e.g. user.message, assistant.message, tool.execution_complete) and converting them into the normalized transcript.jsonl output with assistant tool_use blocks and inlined tool results.

Updates Compact to route truncated input through the new Copilot path before the existing Droid/JSONL handling, and includes a fixture-based test plus expected compact output for Copilot transcripts.

^{Reviewed by Cursor Bugbot for commit 56c7ca0. Configure here.}

[Copilot]

Pull request overview

Adds Copilot CLI support to the transcript “compact” transformer so Copilot’s events.jsonl can be normalized into the repo’s transcript.jsonl format (Checkpoints V2).

Changes:

• Add Copilot-format detection and a Copilot-specific compaction pipeline (user/assistant messages + inlined tool results).
• Add fixture-based regression test coverage for Copilot compaction.
• Add Copilot testdata fixtures (full input + expected compact output).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cmd/entire/cli/transcript/compact/compact.go	Routes Copilot transcripts through the new Copilot compactor.
cmd/entire/cli/transcript/compact/copilot.go	Implements Copilot JSONL detection and compaction logic (incl. inlining tool.execution_complete results).
cmd/entire/cli/transcript/compact/copilot_test.go	Adds a fixture-based test for Copilot compaction.
cmd/entire/cli/transcript/compact/testdata/copilot_full.jsonl	Copilot raw input fixture used by tests.
cmd/entire/cli/transcript/compact/testdata/copilot_expected.jsonl	Expected compact output fixture used by tests.

[computermode]

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