Sessions - isolation/branch picker should handle empty repositories that do not have any commits

[lszomoru]

No description provided.

[Copilot]

Pull request overview

Adjusts the Sessions (Copilot Chat Sessions) isolation and branch selection logic to behave safely when a workspace contains an empty Git repository (no commits / no HEAD.commit), preventing worktree isolation and branch defaults from being derived from an invalid HEAD state.

Changes:

• Disable isolation picker affordances unless the repo has a valid HEAD.commit.
• Force CLI sessions into workspace isolation mode when the opened Git repo has no HEAD.commit.
• Avoid deriving/displaying a “current branch” (and default branch) when HEAD has no commit.

Show a summary per file

File	Description
src/vs/sessions/contrib/copilotChatSessions/browser/isolationPicker.ts	Gates “has git repo” UI enablement on HEAD.commit so empty repos don’t offer isolation switching.
src/vs/sessions/contrib/copilotChatSessions/browser/copilotChatSessionsProvider.ts	Forces workspace isolation for empty repos and avoids branch/default-branch derivation when HEAD.commit is missing.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/sessions/contrib/copilotChatSessions/browser/copilotChatSessionsProvider.ts:346

• Similar to the derived case above: head?.commit ? head.name : undefined may not narrow head to a defined GitBranch in TypeScript, so head.name can produce a strict-null-check compile error. Use an explicit guard like if (head && head.commit) (or keep everything optional-chained) before reading head.name.

				const head = this._gitRepository?.state.get().HEAD;
				const currentBranch = head?.commit ? head.name : undefined;
				this.setBranch(currentBranch ?? this._defaultBranch);

• Files reviewed: 2/2 changed files
• Comments generated: 2