Marcus Sidecar Merge Strategy

Merge Strategy Configuration

This skill covers sidecar's git merge and pull operations, their current implementation, known gaps, and recommended configuration patterns.

Current Implementation

Git Status Plugin Pull Strategies

Location: internal/plugins/gitstatus/pull_menu.go, internal/plugins/gitstatus/remote.go

The git-status plugin offers four pull strategies via a modal menu:

Workspace Plugin Merge Workflows

Location: internal/plugins/workspace/merge.go

PR Workflow:

1. Push branch to remote
2. Create PR via gh pr create
3. Wait for PR merge (polling)
4. Cleanup: delete worktree, branches, pull base

Direct Merge (No PR) at merge.go:430-498:

1. git fetch origin <baseBranch>
2. git checkout <baseBranch>
3. git pull origin <baseBranch>
4. git merge <branch> --no-ff -m "Merge branch '<branch>'"  // Hardcoded --no-ff
5. git push origin <baseBranch>

Post-Merge Pull at merge.go:500-551:

• When on base branch: git pull --ff-only origin <branch> (hardcoded)
• Otherwise: git fetch + git update-ref

Divergence Resolution at merge.go:644-705:

• Rebase option: git pull --rebase origin <branch>
• Merge option: git pull origin <branch>

Known Issues and Gaps

1. No configurable defaults -- users must select strategy every time
2. Limited merge strategies -- direct merge hardcoded to --no-ff, missing --ff, --ff-only, --squash, rebase-based integration
3. No squash merge support -- no clean-history option for main branch
4. Hardcoded commit messages -- fmt.Sprintf("Merge branch '%s'", branch), no templates
5. Missing safety options -- no GPG signing, no --verify-signatures, no --force-with-lease
6. Autostash inconsistency -- available for pull-rebase but not post-merge pull or divergence resolution
7. No upstream tracking config -- remote always origin, no configurable tracking
8. Limited conflict recovery -- only abort or dismiss, no continue/skip rebase
9. No interactive rebase -- no squash/reorder/edit before merge

Recommended Configuration Schema

Add to internal/config/config.go:

type GitConfig struct {
    DefaultPullStrategy  string   `json:"defaultPullStrategy,omitempty"`  // "merge", "rebase", "ff-only", "autostash"
    DefaultMergeStrategy string   `json:"defaultMergeStrategy,omitempty"` // "no-ff", "ff", "ff-only", "squash", "rebase"
    MergeCommitTemplate  string   `json:"mergeCommitTemplate,omitempty"`  // Go template: .Branch, .BaseBranch, .PRTitle, .PRNumber
    SignCommits          bool     `json:"signCommits,omitempty"`
    SignMerges           bool     `json:"signMerges,omitempty"`
    AutostashOnPull      bool     `json:"autostashOnPull,omitempty"`
    DefaultRemote        string   `json:"defaultRemote,omitempty"`        // Default: "origin"
    SetUpstreamOnPush    bool     `json:"setUpstreamOnPush,omitempty"`
    ProtectedBranches    []string `json:"protectedBranches,omitempty"`    // e.g. ["main", "master", "release/*"]
    PreMergeChecks       []string `json:"preMergeChecks,omitempty"`       // e.g. ["go test ./..."]
}

Add to PluginsConfig:

type PluginsConfig struct {
    Git       GitConfig             `json:"git"`
    GitStatus GitStatusPluginConfig `json:"git-status"`
    // ... existing fields
}

Example user config (~/.config/sidecar/config.json):

{
  "plugins": {
    "git": {
      "defaultPullStrategy": "rebase",
      "defaultMergeStrategy": "squash",
      "mergeCommitTemplate": "Merge {{.Branch}} into {{.BaseBranch}}",
      "signCommits": true,
      "autostashOnPull": true,
      "protectedBranches": ["main", "production"]
    }
  }
}

Implementation Priorities

Priority 1: Default Pull Strategy

Files: internal/config/config.go, internal/plugins/gitstatus/pull_menu.go, internal/plugins/gitstatus/update_handlers.go

• If defaultPullStrategy is set, execute directly (skip menu)
• If unset, show menu as today
• Consider adding "Always use this" option to menu

Priority 2: Default Merge Strategy

File: internal/plugins/workspace/merge.go -- performDirectMerge()

func (p *Plugin) performDirectMerge(wt *Worktree) tea.Cmd {
    strategy := p.ctx.Config.Plugins.Git.DefaultMergeStrategy
    if strategy == "" {
        strategy = "no-ff" // backward compatible default
    }
    var mergeArgs []string
    switch strategy {
    case "ff":
        mergeArgs = []string{"merge", branch, "-m", mergeMsg}
    case "ff-only":
        mergeArgs = []string{"merge", branch, "--ff-only"}
    case "squash":
        mergeArgs = []string{"merge", branch, "--squash"}
    case "rebase":
        // 1. git rebase baseBranch branch
        // 2. git checkout baseBranch
        // 3. git merge branch --ff-only
    default: // "no-ff"
        mergeArgs = []string{"merge", branch, "--no-ff", "-m", mergeMsg}
    }
}

Priority 3: Squash Merge Support

After git merge --squash, a separate commit is needed:

case "squash":
    mergeCmd := exec.Command("git", "merge", branch, "--squash")
    // execute...
    commitMsg := fmt.Sprintf("Squash merge branch '%s'", branch)
    commitCmd := exec.Command("git", "commit", "-m", commitMsg)

Priority 4: Merge Commit Templates

type MergeTemplateData struct {
    Branch, BaseBranch, PRTitle, PRNumber string
}

func renderMergeMessage(tmpl string, data MergeTemplateData) (string, error) {
    if tmpl == "" {
        tmpl = "Merge branch '{{.Branch}}'"
    }
    t, err := template.New("merge").Parse(tmpl)
    // ... execute template
}

Priority 5: Protected Branch Warnings

func isProtectedBranch(branch string, patterns []string) bool {
    for _, pattern := range patterns {
        if matched, _ := filepath.Match(pattern, branch); matched {
            return true
        }
    }
    return false
}

Show confirmation modal before direct merge to protected branches.

Strategy Comparison

Team Recommendations

• Open source: default squash, PR workflow recommended
• Internal teams: default no-ff, direct merge acceptable
• Solo developers: default rebase or ff, direct merge for speed

Related Files

Migration Notes

• Empty config = current behavior -- all new fields default to empty/false
• Config validation -- warn on invalid strategy names, do not fail
• Backward compatibility -- if changing defaults, provide migration warnings

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