Lumotia/docs/architecture-map/05-core-storage-hotkey-build/core-process-watch.md

name, type, slice, last_verified

name	type	slice	last_verified
Core process-watch (meeting detection)	architecture-map-page	05-core-storage-hotkey-build	2026/05/09

Core process-watch

Where you are: Architecture map → Core, Storage, Hotkey, Build → Core process-watch

Plain English summary. A lightweight "is the user in a meeting right now?" probe. One signal only: poll the running-process list and match user-editable substrings. No mic-activity heuristic, no calendar integration. If the user has opted in, Magnotia surfaces a non-modal toast so they can choose to start recording. The app never starts recording on its own from this signal.

At a glance

• File: crates/core/src/process_watch.rs (123 LOC, ~40 of which are tests).
• External deps: sysinfo 0.35.
• Public surface: ProcessLister (struct), list_running_process_names, match_meeting_patterns.
• Consumers: slice 2 (a Tauri command holds a long-lived ProcessLister behind Mutex and polls every 15 s).

What's in here

ProcessLister — crates/core/src/process_watch.rs:20

pub struct ProcessLister { system: System }
impl ProcessLister {
    pub fn new() -> Self;
    pub fn snapshot(&mut self) -> Vec<String>;  // lowercased exe names
}
impl Default for ProcessLister { ... }

Reusable wrapper around a sysinfo::System. The system is created once with RefreshKind::nothing().with_processes(ProcessRefreshKind::nothing()) and refreshed in place via refresh_processes(ProcessesToUpdate::All, true) on every call. On a busy host (~300 processes), System::new_with_specifics followed by refresh_processes walks /proc cold and costs ~50–100 ms; reusing the same instance reuses sysinfo's per-process bookkeeping so subsequent refreshes are dominated by diffing rather than allocation.

list_running_process_names() — crates/core/src/process_watch.rs:59

Convenience function. Allocates a fresh ProcessLister per call. Hot paths should hold a long-lived ProcessLister instead.

match_meeting_patterns(process_names, patterns) -> Vec<String> — crates/core/src/process_watch.rs:67

Pure function. Case-insensitive substring match. Returns the set of patterns that matched at least once, in input order, deduped. Empty / whitespace-only patterns are skipped so a stray blank entry in the user's list never matches everything.

Data flow / contract

• The slice-2 command holds the ProcessLister in tauri::State behind a Mutex and polls every 15 seconds.
• Pattern list comes from user settings (the UI surfaces it as a comma-separated text box).
• Match output drives a non-modal toast in the frontend. Magnotia never starts recording itself — the user decides.

Tests

4 tests in crates/core/src/process_watch.rs:84-122:

• matches_are_case_insensitive_substrings — happy path with Zoom Meeting / Microsoft Teams / firefox.
• empty_and_whitespace_patterns_are_ignored — guard.
• matches_are_deduped — duplicate zoom patterns produce one match.
• list_running_returns_something_on_this_host — smoke against the test runner's own process list.

Watch-outs

• refresh_processes(ProcessesToUpdate::All, true) is still ~5–10 ms even reused. OK at 15 s cadence, would not be at sub-second cadence.
• Substring match is broad. The pattern "zoom" matches a process named zoomies (a hypothetical screensaver). User-configurable so the user owns the false positive.
• Lowercased once, searched many times. process_names are lowercased at snapshot time so the matcher itself can stay simple. If we ever want regex matching we will lose this optimisation.
• Linux / macOS / Windows process-name conventions differ. Zoom on macOS, zoom on Linux, Zoom.exe on Windows. The case-insensitive substring match handles the case differences cleanly. The .exe suffix on Windows is fine because the pattern is a substring.
• Privacy. Process names can leak metadata (other apps the user runs). The probe runs locally and the results never leave the machine, but it is a class of data to be careful with.

See also

• Hardware probe — sibling probe.
• Slice 2 Tauri commands for the meeting-detection command that owns the long-lived ProcessLister.