refactor(install): dedupe manager-install fallback and normalize exit conventions (BE-4356)

[mattmillerai]

ELI-5

When you run comfy install, the tool installs ComfyUI-Manager and, if that
install fails, quietly turns the manager off so a later launch doesn't try to
use something that isn't there. That little "install-or-degrade" dance was
written out twice — once for the normal pip path and once for the
--fast-deps path — and the two copies had already started to drift. This PR
folds them into one shared helper so they can't drift again.

While in the file, it also makes the module exit the way the rest of the
codebase does: raise typer.Exit(code=1) instead of sys.exit(...).

What changed

1. Dedupe the manager-install fallback. New module-private helper
   _install_manager_with_fallback(repo_dir, python, *, bootstrap_pip: bool)
   holds the single copy of "install the manager; on failure disable the
   manager GUI mode and warn." Both call sites in execute() (the pip path and
   the fast_deps path) now call it. The only behavioral difference between the
   old copies — the fast_deps path calls ensure_pip(python) first because
   its uv-managed venv may ship no pip, while the pip path already bootstrapped
   pip earlier — is preserved via the bootstrap_pip flag (False for the pip
   path, True for fast_deps). Pure code motion; no behavior change.

2. Normalize exit conventions. The module's six sys.exit(...) calls are
   now raise typer.Exit(code=1), matching the convention used broadly
   elsewhere in the codebase. All of these already propagate straight up to
   main(), which re-raises both typer.Exit and SystemExit identically, so
   the exit code is unchanged (1) for five of them.

⚠️ One intentional observable change

sys.exit(-1) on the "path exists but isn't a recognized ComfyUI repo" branch
previously produced shell exit code 255 (a negative arg wraps to 255); it
now produces 1, like every other failure in the module. This is the only
user-visible change and is a deliberate normalization.

Notes / judgment calls

• Deferred as ticketed: the full _install_deps_pip / _install_deps_fast
  two-strategy extraction is intentionally not done here — install is the
  highest-blast-radius command and the groom verdict downgraded scope to just
  the concrete dedupe + exit normalization. Defer that split until install next
  changes for feature reasons.
• Test update: typer.Exit is not a subclass of SystemExit, so the
  one existing test asserting pytest.raises(SystemExit) on
  checkout_stable_comfyui was updated to pytest.raises(typer.Exit). I
  verified none of the six exit sites sit inside a broad except Exception: in
  their call path (which would newly swallow a typer.Exit where SystemExit
  escaped) — they all propagate to main() unchanged.
• New coverage: added TestInstallManagerWithFallback locking the helper's
  bootstrap-vs-not behavior and the degrade-on-failure config write.

Testing

• Full unit suite green: 2670 passed, 13 skipped (uv run pytest tests/comfy_cli).
• ruff check + ruff format --check clean on the touched files.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 5cbc462c-32c0-4528-ac82-bb20c8941851

📥 Commits

Reviewing files that changed from the base of the PR and between 85b62da and 6ad55d7.

📒 Files selected for processing (3)

• comfy_cli/command/install.py
• tests/comfy_cli/command/github/test_pr.py
• tests/comfy_cli/test_install.py

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📝 Walkthrough

Walkthrough

Installation failures now consistently raise typer.Exit, while ComfyUI-Manager setup uses a shared fallback that can disable manager GUI mode after installation failure. Tests cover both behaviors.

Changes

Install reliability

Layer / File(s)	Summary
ComfyUI-Manager fallback installation comfy_cli/command/install.py, tests/comfy_cli/test_install.py	Manager setup is centralized in a helper supporting optional pip bootstrapping, installation, GUI-mode disabling on failure, and branch coverage.
Typer exit handling comfy_cli/command/install.py, tests/comfy_cli/command/github/test_pr.py	Dependency, repository, release, and checkout failures raise typer.Exit(code=1); the related test expects typer.Exit.

Sequence Diagram(s)

sequenceDiagram
  participant InstallCommand
  participant ManagerFallback
  participant Pip
  participant ConfigManager
  InstallCommand->>ManagerFallback: install ComfyUI-Manager
  ManagerFallback->>Pip: bootstrap pip when enabled
  ManagerFallback->>Pip: install manager
  Pip-->>ManagerFallback: success or failure
  ManagerFallback->>ConfigManager: disable manager GUI mode on failure

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Suggested reviewers: bigcat88

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch matt/be-4356-dedupe-manager-fallback

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch matt/be-4356-dedupe-manager-fallback

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[github-actions]

🔍 Cursor Review — Consolidated panel

Triggered by @mattmillerai.

✅ No high-signal findings.

Panel: 6/8 reviewers contributed findings.

Reviewers that did not contribute: kimi-k2.5:adversarial (empty), kimi-k2.5:edge-case (empty)