fix(hooks): eliminate redundant disk reads on every hook invocation

src/core/config.rs

@@ -4,6 +4,9 @@ use super::constants::{CONFIG_TOML, DEFAULT_HISTORY_DAYS, RTK_DATA_DIR};
 use anyhow::Result;
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
+use std::sync::OnceLock;
+
+static CONFIG_CACHE: OnceLock<Config> = OnceLock::new();
 
 #[derive(Debug, Serialize, Deserialize, Default)]
 pub struct Config {
@@ -163,6 +166,15 @@ impl Config {
         }
     }
 
+    /// Load config with process-lifetime caching.
+    ///
+    /// C-08 hot-path fix: hook invocations call this instead of `load()` so
+    /// `config.toml` is read at most once per `rtk hook` process. Falls back to
+    /// `Config::default()` on load failure so hook execution is never blocked.
+    pub fn load_cached() -> &'static Config {
+        CONFIG_CACHE.get_or_init(|| Config::load().unwrap_or_default())
+    }
+
     pub fn save(&self) -> Result<()> {
         let path = get_config_path()?;
 

src/core/telemetry.rs

@@ -23,12 +23,26 @@ pub fn maybe_ping() {
         return;
     }
 
-    // Check opt-out: env var
+    // Check opt-out: env var (cheap — before any disk I/O)
     if std::env::var("RTK_TELEMETRY_DISABLED").unwrap_or_default() == "1" {
         return;
     }
 
-    // Load config once (avoid double disk read)
+    // C-08 fix: check the day-marker BEFORE loading config.
+    // On the hot path (hook invocation), the marker is almost always fresh,
+    // so we skip the config.toml disk read entirely on 99% of calls.
+    let marker = telemetry_marker_path();
+    if let Ok(metadata) = std::fs::metadata(&marker) {
+        if let Ok(modified) = metadata.modified() {
+            if let Ok(elapsed) = modified.elapsed() {
+                if elapsed.as_secs() < PING_INTERVAL_SECS {
+                    return;
+                }
+            }
+        }
+    }
+
+    // Marker is stale (or absent) — load config to check consent before pinging.
     let cfg = match config::Config::load() {
         Ok(c) => c,
         Err(_) => return,
@@ -45,18 +59,6 @@ pub fn maybe_ping() {
         return;
     }
 
-    // Check last ping time
-    let marker = telemetry_marker_path();
-    if let Ok(metadata) = std::fs::metadata(&marker) {
-        if let Ok(modified) = metadata.modified() {
-            if let Ok(elapsed) = modified.elapsed() {
-                if elapsed.as_secs() < PING_INTERVAL_SECS {
-                    return;
-                }
-            }
-        }
-    }
-
     // Touch marker file immediately (before sending) to avoid double-ping
     touch_marker(&marker);
 

src/hooks/hook_check.rs

@@ -94,15 +94,10 @@ pub fn maybe_warn() {
 
 /// Single source of truth: delegates to `status()` then rate-limits the warning.
 fn check_and_warn() -> Option<()> {
-    let warning = match status() {
-        HookStatus::Ok => return Some(()),
-        HookStatus::Missing => {
-            "[rtk] /!\\ No hook installed — run `rtk init -g` for automatic token savings"
-        }
-        HookStatus::Outdated => "[rtk] /!\\ Hook outdated — run `rtk init -g` to update",
-    };
-
-    // Rate limit: warn once per day
+    // C-08 fix: check the rate-limit marker BEFORE calling status().
+    // status() reads settings.json unconditionally — skipping it on the hot path
+    // (recent marker → already warned today) avoids that disk read on every
+    // hook invocation.
     let marker = warn_marker_path()?;
     if let Ok(meta) = std::fs::metadata(&marker) {
         if let Ok(modified) = meta.modified() {
@@ -112,6 +107,14 @@ fn check_and_warn() -> Option<()> {
         }
     }
 
+    let warning = match status() {
+        HookStatus::Ok => return Some(()),
+        HookStatus::Missing => {
+            "[rtk] /!\\ No hook installed — run `rtk init -g` for automatic token savings"
+        }
+        HookStatus::Outdated => "[rtk] /!\\ Hook outdated — run `rtk init -g` to update",
+    };
+
     eprintln!("{}", warning);
 
     // Touch marker after warning is printed

src/hooks/hook_cmd.rs

@@ -40,6 +40,7 @@ enum HookFormat {
 /// Run the Copilot preToolUse hook.
 /// Auto-detects VS Code Copilot Chat vs Copilot CLI format.
 pub fn run_copilot() -> Result<()> {
+    std::env::set_var("RTK_HOOK_MODE", "1");
     let input = read_stdin_limited()?;
 
     let input = input.trim();
@@ -107,9 +108,9 @@ fn get_rewritten(cmd: &str) -> Option<String> {
         return None;
     }
 
-    let (excluded, transparent_prefixes) = crate::core::config::Config::load()
-        .map(|c| (c.hooks.exclude_commands, c.hooks.transparent_prefixes))
-        .unwrap_or_default();
+    let cfg = crate::core::config::Config::load_cached();
+    let excluded = cfg.hooks.exclude_commands.clone();
+    let transparent_prefixes = cfg.hooks.transparent_prefixes.clone();
 
     let rewritten = rewrite_command(cmd, &excluded, &transparent_prefixes)?;
 
@@ -181,6 +182,7 @@ fn handle_copilot_cli(cmd: &str) -> Result<()> {
 
 /// Run the Gemini CLI BeforeTool hook.
 pub fn run_gemini() -> Result<()> {
+    std::env::set_var("RTK_HOOK_MODE", "1");
     let input = read_stdin_limited()?;
 
     let json: Value = serde_json::from_str(&input).context("Failed to parse hook input as JSON")?;
@@ -211,9 +213,9 @@ pub fn run_gemini() -> Result<()> {
         return Ok(());
     }
 
-    let (excluded, transparent_prefixes) = crate::core::config::Config::load()
-        .map(|c| (c.hooks.exclude_commands, c.hooks.transparent_prefixes))
-        .unwrap_or_default();
+    let cfg = crate::core::config::Config::load_cached();
+    let excluded = cfg.hooks.exclude_commands.clone();
+    let transparent_prefixes = cfg.hooks.transparent_prefixes.clone();
 
     match rewrite_command(cmd, &excluded, &transparent_prefixes) {
         Some(ref rewritten) => {
@@ -355,6 +357,7 @@ fn process_claude_payload(v: &Value) -> PayloadAction {
 
 /// Run the Claude Code PreToolUse hook natively.
 pub fn run_claude() -> Result<()> {
+    std::env::set_var("RTK_HOOK_MODE", "1");
     let input = read_stdin_limited()?;
 
     let input = input.trim();
@@ -413,6 +416,7 @@ fn strip_leading_bom(input: &str) -> &str {
 
 /// Run the Cursor Agent hook natively.
 pub fn run_cursor() -> Result<()> {
+    std::env::set_var("RTK_HOOK_MODE", "1");
     let input = read_stdin_limited()?;
 
     let input = strip_leading_bom(&input).trim();