cli: try squash merge first, fall back to merge commit if not allowed

[Copilot]

Repositories that restrict merge commits fail the gh pr merge --merge call with GraphQL: Merge commits are not allowed on this repository. — making gh aw add unable to auto-merge the setup PR.

Changes

• mergePullRequest merge strategy — attempts squash merge first (--squash); if the repository does not permit squash merges, detects the GitHub GraphQL error (case-insensitive, checked against both combined output and error string) and retries with a merge commit (--merge)
• squashMergeNotAllowedErr constant — names the expected error substring for clarity and easy updates if the API message ever changes
• Informs the user via console.FormatInfoMessage before the retry so the strategy change is visible

[pelikhan]

@copilot try squash merge first

[Copilot]

@copilot try squash merge first

Done in 68d7c2e. Squash merge is now attempted first; if the repo doesn't allow squash merges, it falls back to a merge commit.

[Copilot]

Pull request overview

Updates the interactive add flow’s PR auto-merge behavior to handle repositories with merge-method restrictions by trying squash merges first and retrying with a merge commit when squash merges are disallowed.

Changes:

• Add detection for “squash merges are not allowed” errors from gh pr merge --squash.
• Attempt gh pr merge --squash first, and fall back to --merge on the detected restriction.
• Print an informational message when switching strategies so the retry is visible to the user.

Show a summary per file

File	Description
pkg/cli/add_interactive_git.go	Implements squash-first merge strategy with fallback to merge-commit when squash merges aren’t permitted.

Copilot's findings

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Comments suppressed due to low confidence (1)

pkg/cli/add_interactive_git.go:305

• If the fallback --merge attempt fails, the returned error only includes the merge-commit output, losing the original squash failure context (and why the retry happened). Consider including both the initial squash error/output and the merge-commit error/output in the final error, so diagnosis doesn’t depend on having seen the transient stderr info message.

	if strings.Contains(combinedText, squashMergeNotAllowedErr) {
		fmt.Fprintln(os.Stderr, console.FormatInfoMessage("Squash merges are not allowed on this repository, retrying with merge commit"))
		mergeOutput, mergeErr := workflow.RunGHCombined("Merging pull request...", "pr", "merge", prArg, "--repo", c.RepoOverride, "--merge")
		if mergeErr != nil {
			return fmt.Errorf("merge failed: %w (output: %s)", mergeErr, string(mergeOutput))
		}

• Files reviewed: 1/1 changed files
• Comments generated: 1

[Copilot]

The returned error message always says "merge failed" even when the attempted strategy was a squash merge. This makes troubleshooting harder (e.g., users can’t tell whether the failure came from --squash vs the retry path). Consider making the error text strategy-specific (e.g., "squash merge failed") so the surfaced error matches what was attempted.

This issue also appears on line 300 of the same file.