thanks for the pr twin, i appreciate the effort and the intent to make kill() handling more explicit.
but we have a few issues to address before we can merge this PR

1. Update the API and all call sites (pick one of these)

• Option A (preferred, non-breaking): add a new fallible helper:
  • pub fn kill_process_sigterm_result(pid: i32) -> Result<(), std::io::Error>
  • keep the existing pub fn kill_process_sigterm(pid: i32) wrapper that calls the new helper and ignores/logs the Result.
  • Update only the sensitive call site(s) (see - 4) to use the new _result helper and handle errors.
• Option B (breaking, if you want to enforce handling everywhere): change kill_process_sigterm to return Result and update every internal caller in the repo to handle Result. If you choose this, note that it’s an incompatible source change — we’ll treat it as internal until dev → main, but be explicit in the PR description about the breaking nature.

2. Fix the cclip lock path semantics (must do)

• In run_cclip_mode (src/main.rs) the code currently calls kill_process_sigterm(pid) and then removes the lockfile unconditionally. That can allow a second instance to start if kill() fails (EPERM) while the old process remained alive.
• Update that flow so we only remove the lock when:
  • kill succeeded (OK), or
  • the error is ESRCH (no such process).
• For EPERM or other errors, return an error or surface a clear message so we don’t silently remove the lockfile.

3. Be consistent with other kill usages

• The repo contains inline libc::kill uses (e.g. src/modes/app_launcher/run.rs) that implement a “send SIGTERM, poll via kill(..., 0), then SIGKILL” pattern.
• Either leave those inline behaviors alone (recommended) or refactor them to use the new helper consistently. If you refactor, keep the existing escalation logic intact.

4. Tests / build / lint

• Run cargo build and cargo test locally and report results in the PR.
• Run cargo fmt and cargo clippy; fix any warnings/errors you introduce.
• If possible, add a test or mention manual steps that exercise the cclip lock path (simulate ESRCH/EPERM behavior) so reviewers can reproduce reasoning.

5. PR description and metadata

• Update the PR description to follow CONTRIBUTING.md: summary of changes, tests performed, and whether this is breaking or not.

• If you changed behavior (e.g., how the lockfile is removed), note that in the description.

• If you want, tag me or @me in the comment when you’ve pushed the updates and I’ll re-review quickly. I also retarget the base to dev for you as per the CONTRIBUTING.md guided.

thanks again — the change makes sense and i'm happy to merge once the PR compiles cleanly in-tree, and either preserves backwards compatibility via a wrapper or updates all call sites and documents it.

@Mjoyufull review code