multiple feature and performance improvements (see description)

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Release notes — 2025-08-12

Highlights

Agent back to near-zero CPU when idle (request-driven, no background samplers).
Accurate per-process CPU% via /proc deltas; only top-level processes (threads hidden).
TUI: processes pane gets scrollbar, click-to-sort (CPU% or Mem) with indicator, stable total count.
Network panes made taller; disks slightly reduced.
README revamped: rustup prereqs, crates.io install, update/systemd instructions.
Clippy cleanups across agent and client.
Agent

Reverted precompressed caches and background samplers; WebSocket path is request-driven again.
Ensured on-demand gzip for larger replies; no per-request overhead when small.
Processes: switched to refresh_processes_specifics with ProcessRefreshKind::everything().without_tasks() to exclude threads.
Per-process CPU% now computed from /proc jiffies deltas using a small ProcCpuTracker (fixes “always 0%”/scaling issues).
Optional metrics and light caching:
CPU temp and GPU metrics gated by env (SOCKTOP_AGENT_TEMP=0, SOCKTOP_AGENT_GPU=0).
Tiny TTL caches via once_cell to avoid rescanning sensors every tick.
Dependencies: added once_cell = "1.19".
No API changes to WS endpoints.
Client (TUI)

Processes pane:
Scrollbar (mouse wheel, drag; keyboard arrows/PageUp/PageDown/Home/End).
Click header to sort by CPU% or Mem; dot indicator on active column.
Preserves process_count across fast metrics updates to avoid flicker.
UI/theme:
Shared scrollbar colors moved to ui/theme.rs; both CPU and Processes reuse them.
Cached pane rect to fix input handling; removed unused vars.
Layout: network download/upload get more vertical space; disks shrink slightly.
Clippy fixes: derive Default for ProcSortBy; style/import cleanups.
Docs

README: added rustup install steps (with proper shell reload), install via cargo install socktop and cargo install socktop_agent, and a clear Updating section (systemd service steps included).
Features list updated; roadmap marks independent cadences as done.
Upgrade notes

Agent: cargo install socktop_agent --force, then restart your systemd service; if unit changed, systemctl daemon-reload.
TUI: cargo install socktop --force.
Optional envs to trim overhead: SOCKTOP_AGENT_GPU=0, SOCKTOP_AGENT_TEMP=0.
No config or API breaking changes.

socktop_agent/src/state.rs

@@ -1,49 +1,52 @@
 //! Shared agent state: sysinfo handles and hot JSON cache.
 
+use std::collections::HashMap;
 use std::sync::atomic::AtomicUsize;
 use std::sync::Arc;
 use sysinfo::{Components, Disks, Networks, System};
-use tokio::sync::{Mutex, Notify, RwLock};
+use tokio::sync::Mutex;
 
 pub type SharedSystem = Arc<Mutex<System>>;
 pub type SharedComponents = Arc<Mutex<Components>>;
 pub type SharedDisks = Arc<Mutex<Disks>>;
 pub type SharedNetworks = Arc<Mutex<Networks>>;
 
+#[derive(Default)]
+pub struct ProcCpuTracker {
+    pub last_total: u64,
+    pub last_per_pid: HashMap<u32, u64>,
+}
+
 #[derive(Clone)]
 pub struct AppState {
-    // Persistent sysinfo handles
     pub sys: SharedSystem,
-
-    // Last serialized JSON snapshot for fast WS responses
-    pub last_json: Arc<RwLock<String>>,
-
-    // Adaptive sampling controls
-    pub client_count: Arc<AtomicUsize>,
-    pub wake_sampler: Arc<Notify>,
-    pub auth_token: Option<String>,
-
-    // Cached containers (enumerated once; refreshed per tick)
     pub components: SharedComponents,
     pub disks: SharedDisks,
     pub networks: SharedNetworks,
+
+    // For correct per-process CPU% using /proc deltas
+    pub proc_cpu: Arc<Mutex<ProcCpuTracker>>,
+
+    // Connection tracking (to allow future idle sleeps if desired)
+    pub client_count: Arc<AtomicUsize>,
+
+    pub auth_token: Option<String>,
 }
 
 impl AppState {
-    #[allow(dead_code)]
     pub fn new() -> Self {
-        let sys = System::new(); // targeted refreshes per tick
-        let components = Components::new_with_refreshed_list(); // enumerate once
+        let sys = System::new();
+        let components = Components::new_with_refreshed_list();
         let disks = Disks::new_with_refreshed_list();
         let networks = Networks::new_with_refreshed_list();
+
         Self {
             sys: Arc::new(Mutex::new(sys)),
             components: Arc::new(Mutex::new(components)),
             disks: Arc::new(Mutex::new(disks)),
             networks: Arc::new(Mutex::new(networks)),
-            last_json: Arc::new(RwLock::new(String::new())),
+            proc_cpu: Arc::new(Mutex::new(ProcCpuTracker::default())),
             client_count: Arc::new(AtomicUsize::new(0)),
-            wake_sampler: Arc::new(Notify::new()),
             auth_token: std::env::var("SOCKTOP_TOKEN")
                 .ok()
                 .filter(|s| !s.is_empty()),