fix: propagate headers through OpenCode MCP adapter

[alopezsanchez]

Description

_to_opencode_format was not mapping remote server headers from the Copilot-format config into OpenCode's schema. When a remote MCP server declared headers (e.g. Authorization), they were silently dropped from opencode.json.

It also adds a comprehensive test suite to the Opencode MCP adapter.

Fixes #621

Type of change

• Bug fix
• New feature
• Documentation
• Maintenance / refactor

Testing

• Tested locally
• All existing tests pass
• Added tests for new functionality (if applicable)

[Copilot]

Pull request overview

Fixes OpenCode MCP config generation so remote server headers from Copilot-format configs are preserved when writing opencode.json, and adds a dedicated unit test suite to prevent regressions.

Changes:

• Propagate headers for remote MCP entries in OpenCodeClientAdapter._to_opencode_format().
• Add comprehensive unit tests covering OpenCode MCP config read/write, conversion, and stale cleanup behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/apm_cli/adapters/client/opencode.py	Copies remote headers into OpenCode schema during Copilot->OpenCode config conversion.
tests/unit/test_opencode_mcp.py	Adds unit tests for OpenCode adapter behavior, including remote headers and MCPIntegrator.remove_stale() cleanup.

[sergio-sisternes-epam]

Thanks for this, @alopezsanchez! Great catch on the dropped headers, and the test coverage you added is really appreciated.

Two small suggestions:

1. Defensive copy on env — You copy headers with dict(headers) to prevent mutation, but env is assigned by reference on L156. Worth applying the same dict(env) pattern for consistency.

2. CHANGELOG entry — Could you add a line under ## [Unreleased] → ### Fixed for the header propagation fix?

Neither is a blocker — happy to merge once addressed. Nice work!

[alopezsanchez]

Thanks for this, @alopezsanchez! Great catch on the dropped headers, and the test coverage you added is really appreciated.

Two small suggestions:

1. Defensive copy on env — You copy headers with dict(headers) to prevent mutation, but env is assigned by reference on L156. Worth applying the same dict(env) pattern for consistency.
2. CHANGELOG entry — Could you add a line under ## [Unreleased] → ### Fixed for the header propagation fix?

Neither is a blocker — happy to merge once addressed. Nice work!

Sure thing! Will do 👍🏻

[alopezsanchez]

@sergio-sisternes-epam done!

[sergio-sisternes-epam]

@danielmeppiel this will need your "Merge pull request" capabilities :)