fix: 6 bugs found during fresh-eyes code review

1. cache: record diagnostic miss before early-return on modified()/duration_since() failure
2. dump-state: resolve all cache_dir template vars ({cache_version}, {config_hash})
3. config: remove dead breakpoint_hysteresis field from GlobalConfig (breakpoints.hysteresis is used)
4. config: align Rust Default cache_dir with defaults.json template
5. vcs: apply branch truncation in render_stale_cache (--no-shell path)
6. vcs: fix jj prefetch retry on already-failed command (flatten→unwrap_or_else)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/bin/claude-statusline.rs

@@ -229,6 +229,7 @@ fn main() {
             vcs_type,
             project_dir,
             &session,
+            &config_hash,
             &ctx,
         );
         return;
@@ -404,6 +405,7 @@ fn dump_state_output(
     vcs: section::VcsType,
     project_dir: &str,
     session_id: &str,
+    config_hash: &str,
     ctx: &RenderContext,
 ) {
     // Render all sections with per-section timing
@@ -468,7 +470,10 @@ fn dump_state_output(
         "cache": cache_diags,
         "paths": {
             "project_dir": project_dir,
-            "cache_dir": config.global.cache_dir.replace("{session_id}", session_id),
+            "cache_dir": config.global.cache_dir
+                .replace("{session_id}", session_id)
+                .replace("{cache_version}", &config.global.cache_version.to_string())
+                .replace("{config_hash}", config_hash),
         },
         "session_id": session_id,
     });

src/cache.rs

@@ -95,8 +95,20 @@ impl Cache {
                 return None;
             }
         };
-        let modified = meta.modified().ok()?;
-        let age = SystemTime::now().duration_since(modified).ok()?;
+        let modified = match meta.modified().ok() {
+            Some(m) => m,
+            None => {
+                self.record_diag(key, false, None);
+                return None;
+            }
+        };
+        let age = match SystemTime::now().duration_since(modified).ok() {
+            Some(a) => a,
+            None => {
+                self.record_diag(key, false, None);
+                return None;
+            }
+        };
         let age_ms = age.as_millis() as u64;
         let effective_ttl = self.jittered_ttl(key, ttl);
         if age < effective_ttl {

src/config.rs

@@ -69,7 +69,6 @@ pub struct GlobalConfig {
     pub shell_env: HashMap<String, String>,
     pub cache_version: u32,
     pub drop_strategy: String,
-    pub breakpoint_hysteresis: u16,
 }
 
 impl Default for GlobalConfig {
@@ -80,7 +79,7 @@ impl Default for GlobalConfig {
             vcs: "auto".into(),
             width: None,
             width_margin: 4,
-            cache_dir: "/tmp/claude-sl-{session_id}".into(),
+            cache_dir: "/tmp/claude-sl-{session_id}-{cache_version}-{config_hash}".into(),
             cache_gc_days: 7,
             cache_gc_interval_hours: 24,
             cache_ttl_jitter_pct: 10,
@@ -100,7 +99,6 @@ impl Default for GlobalConfig {
             shell_env: HashMap::new(),
             cache_version: 1,
             drop_strategy: "tiered".into(),
-            breakpoint_hysteresis: 2,
         }
     }
 }

src/section/vcs.rs

@@ -30,7 +30,13 @@ pub fn render(ctx: &RenderContext) -> Option<SectionOutput> {
 
 /// Serve stale cached VCS data without running any commands.
 fn render_stale_cache(ctx: &RenderContext) -> Option<SectionOutput> {
-    let branch = ctx.cache.get_stale("vcs_branch")?;
+    let branch_raw = ctx.cache.get_stale("vcs_branch")?;
+    let trunc = &ctx.config.sections.vcs.truncate;
+    let branch = if trunc.enabled && trunc.max > 0 {
+        crate::format::truncate(&branch_raw, trunc.max, &trunc.style)
+    } else {
+        branch_raw
+    };
     let branch_glyph = glyph::glyph("branch", &ctx.config.glyphs);
     let raw = format!("{branch_glyph}{branch}");
     let ansi = if ctx.color_enabled {
@@ -164,13 +170,8 @@ fn render_jj(
     let branch_ttl = Duration::from_secs(ttl.branch);
 
     let branch = ctx.cache.get("vcs_branch", branch_ttl).or_else(|| {
-        // Use prefetched result if available
-        let out = ctx
-            .shell_results
-            .get("vcs")
-            .cloned()
-            .flatten()
-            .or_else(|| {
+        // Use prefetched result if available, otherwise exec
+        let out = ctx.shell_results.get("vcs").cloned().unwrap_or_else(|| {
             shell::exec_gated(
                 ctx.shell_config,
                 "jj",