experience-mine: split oversized sessions at compaction boundaries

Claude Code doesn't create new session files on context compaction —
a single UUID can accumulate 170+ conversations, producing 400MB+
JSONL files that generate 1.3M token prompts.

Split at compaction markers ("This session is being continued..."):
- extract_conversation made pub, split_on_compaction splits messages
- experience_mine takes optional segment index
- daemon watcher parses files, spawns per-segment jobs (.0, .1, .2)
- seg_cache memoizes segment counts across ticks
- per-segment dedup keys; whole-file key when all segments complete
- 150K token guard skips any remaining oversized segments
- char-boundary-safe truncation in enrich.rs and fact_mine.rs

Backwards compatible: unsegmented calls still write content-hash
dedup keys, old whole-file mined keys still recognized.

src/daemon.rs

@@ -13,7 +13,7 @@
 // Phase 2 will inline job logic; Phase 3 integrates into poc-agent.
 
 use jobkit::{Choir, ExecutionContext, ResourcePool, TaskError, TaskInfo, TaskStatus};
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 use std::fs;
 use std::io::Write;
 use std::path::{Path, PathBuf};
@@ -97,13 +97,13 @@ fn run_job(ctx: &ExecutionContext, name: &str, f: impl FnOnce() -> Result<(), St
     }
 }
 
-fn job_experience_mine(ctx: &ExecutionContext, path: &str) -> Result<(), TaskError> {
+fn job_experience_mine(ctx: &ExecutionContext, path: &str, segment: Option<usize>) -> Result<(), TaskError> {
     let path = path.to_string();
     run_job(ctx, &format!("experience-mine {}", path), || {
         ctx.log_line("loading store");
         let mut store = crate::store::Store::load()?;
         ctx.log_line("mining");
-        let count = crate::enrich::experience_mine(&mut store, &path)?;
+        let count = crate::enrich::experience_mine(&mut store, &path, segment)?;
         ctx.log_line(&format!("{} entries mined", count));
         Ok(())
     })
@@ -323,6 +323,8 @@ pub fn run_daemon() -> Result<(), String> {
     let last_daily_sw = Arc::clone(&last_daily);
     choir.spawn("session-watcher").init(move |ctx| {
         ctx.set_progress("idle");
+        // Cache segment counts so we don't re-parse large files every tick
+        let mut seg_cache: HashMap<String, usize> = HashMap::new();
         loop {
             if ctx.is_cancelled() {
                 return Err(TaskError::Fatal("cancelled".into()));
@@ -366,10 +368,13 @@ pub fn run_daemon() -> Result<(), String> {
             let mut already_mined = 0;
             let mut still_open = 0;
             let total_stale = stale.len();
+            // Multi-segment files where all segments are done — write whole-file key
+            let mut mark_transcript_done: Vec<(String, String, usize)> = Vec::new();
 
-            // Classify each session
+            // Classify each session — now segment-aware
-            let mut needs_extract: Vec<(PathBuf, String, String)> = Vec::new();
+            // Each entry: (filename, path_str, segment_index)
-            let mut needs_fact: Vec<(PathBuf, String, String)> = Vec::new();
+            let mut needs_extract: Vec<(String, String, Option<usize>)> = Vec::new();
+            let mut needs_fact: Vec<(String, String)> = Vec::new();
 
             for session in stale {
                 let filename = session.file_name()
@@ -377,44 +382,84 @@ pub fn run_daemon() -> Result<(), String> {
                     .unwrap_or_else(|| "unknown".into());
                 let path_str = session.to_string_lossy().to_string();
 
-                // Skip if already in-flight
+                // Check for old-style whole-file mined key
-                let extract_name = format!("extract:{}", filename);
-                let fact_name = format!("fact-mine:{}", filename);
-                if active.contains(&extract_name) || active.contains(&fact_name) {
-                    continue;
-                }
-
                 let experience_done = crate::enrich::is_transcript_mined_with_keys(&mined, &path_str);
-                let fact_key = format!("_facts-{}", filename.trim_end_matches(".jsonl"));
-                let fact_done = fact_keys.contains(&fact_key);
 
                 if !experience_done {
                     if is_file_open(&session) {
                         still_open += 1;
-                    } else {
+                        continue;
-                        needs_extract.push((session, filename, path_str));
+                    }
+
+                    // Get segment count, using cache to avoid re-parsing large files
+                    let seg_count = if let Some(&cached) = seg_cache.get(&path_str) {
+                        cached
+                    } else {
+                        let messages = match crate::enrich::extract_conversation(&path_str) {
+                            Ok(m) => m,
+                            Err(_) => continue,
+                        };
+                        let count = crate::enrich::split_on_compaction(messages).len();
+                        seg_cache.insert(path_str.clone(), count);
+                        count
+                    };
+
+                    if seg_count <= 1 {
+                        let task_name = format!("extract:{}", filename);
+                        if !active.contains(&task_name) {
+                            needs_extract.push((filename, path_str, None));
+                        }
+                    } else {
+                        // Multi-segment — find unmined segments
+                        let fname_key = crate::enrich::transcript_filename_key(&path_str);
+                        let mut unmined = 0;
+                        for i in 0..seg_count {
+                            let seg_key = format!("{}.{}", fname_key, i);
+                            if mined.contains(&seg_key) { continue; }
+                            unmined += 1;
+                            let task_name = format!("extract:{}.{}", filename, i);
+                            if active.contains(&task_name) { continue; }
+                            needs_extract.push((
+                                format!("{}.{}", filename, i),
+                                path_str.clone(),
+                                Some(i),
+                            ));
+                        }
+                        if unmined == 0 {
+                            // All segments done — write whole-file key so we skip next tick
+                            mark_transcript_done.push((fname_key, path_str.clone(), seg_count));
+                            already_mined += 1;
+                        }
+                    }
+                } else {
+                    let fact_key = format!("_facts-{}", filename.trim_end_matches(".jsonl"));
+                    let fact_done = fact_keys.contains(&fact_key);
+                    if !fact_done {
+                        let task_name = format!("fact-mine:{}", filename);
+                        if !active.contains(&task_name) {
+                            needs_fact.push((filename, path_str));
                         }
-                } else if !fact_done {
-                    needs_fact.push((session, filename, path_str));
                     } else {
                         already_mined += 1;
                     }
                 }
+            }
 
             // Spawn experience-mine jobs (priority)
-            for (_, filename, path_str) in &needs_extract {
+            for (task_label, path_str, segment) in &needs_extract {
                 if extract_queued >= MAX_NEW_PER_TICK {
                     extract_remaining += 1;
                     continue;
                 }
-                let task_name = format!("extract:{}", filename);
+                let task_name = format!("extract:{}", task_label);
-                log_event("extract", "queued", path_str);
+                log_event("extract", "queued", &task_name);
                 let path = path_str.clone();
+                let seg = *segment;
                 choir_sw.spawn(task_name)
                     .resource(&llm_sw)
                     .retries(2)
                     .init(move |ctx| {
-                        job_experience_mine(ctx, &path)
+                        job_experience_mine(ctx, &path, seg)
                     });
                 extract_queued += 1;
             }
@@ -423,7 +468,7 @@ pub fn run_daemon() -> Result<(), String> {
             let mut fact_queued = 0;
             if needs_extract.len() == extract_queued {
                 let fact_budget = MAX_NEW_PER_TICK.saturating_sub(extract_queued);
-                for (_, filename, path_str) in &needs_fact {
+                for (filename, path_str) in &needs_fact {
                     if fact_queued >= fact_budget {
                         fact_remaining += 1;
                         continue;
@@ -443,6 +488,21 @@ pub fn run_daemon() -> Result<(), String> {
                 fact_remaining = needs_fact.len();
             }
 
+            // Write whole-file keys for fully-mined multi-segment files
+            if !mark_transcript_done.is_empty() {
+                if let Ok(mut store) = crate::store::Store::load() {
+                    for (fname_key, path_str, seg_count) in &mark_transcript_done {
+                        let content = format!("All {} segments mined for {}", seg_count, path_str);
+                        let mut node = crate::store::new_node(fname_key, &content);
+                        node.category = crate::store::Category::Task;
+                        node.provenance = crate::store::Provenance::AgentExperienceMine;
+                        let _ = store.upsert_node(node);
+                        seg_cache.remove(path_str);
+                    }
+                    let _ = store.save();
+                }
+            }
+
             let extract_pending = extract_queued + extract_remaining;
             let fact_pending = fact_queued + fact_remaining;
             if extract_pending > 0 || fact_pending > 0 || still_open > 0 {

src/enrich.rs

@@ -85,7 +85,7 @@ pub fn is_transcript_mined_with_keys(mined: &HashSet<String>, path: &str) -> boo
 
 /// Extract user/assistant messages with line numbers from a JSONL transcript.
 /// (line_number, role, text, timestamp)
-fn extract_conversation(jsonl_path: &str) -> Result<Vec<(usize, String, String, String)>, String> {
+pub fn extract_conversation(jsonl_path: &str) -> Result<Vec<(usize, String, String, String)>, String> {
     let content = fs::read_to_string(jsonl_path)
         .map_err(|e| format!("read {}: {}", jsonl_path, e))?;
 
@@ -135,6 +135,33 @@ fn extract_conversation(jsonl_path: &str) -> Result<Vec<(usize, String, String,
     Ok(messages)
 }
 
+pub const COMPACTION_MARKER: &str = "This session is being continued from a previous conversation that ran out of context";
+
+/// Split extracted messages into segments at compaction boundaries.
+/// Each segment represents one continuous conversation before context was compacted.
+pub fn split_on_compaction(messages: Vec<(usize, String, String, String)>) -> Vec<Vec<(usize, String, String, String)>> {
+    let mut segments: Vec<Vec<(usize, String, String, String)>> = Vec::new();
+    let mut current = Vec::new();
+
+    for msg in messages {
+        if msg.1 == "user" && msg.2.starts_with(COMPACTION_MARKER) {
+            if !current.is_empty() {
+                segments.push(current);
+                current = Vec::new();
+            }
+            // The continuation message itself is part of the new segment
+            current.push(msg);
+        } else {
+            current.push(msg);
+        }
+    }
+    if !current.is_empty() {
+        segments.push(current);
+    }
+
+    segments
+}
+
 /// Format conversation messages for the prompt (truncating long messages).
 fn format_conversation(messages: &[(usize, String, String, String)]) -> String {
     messages.iter()
@@ -259,9 +286,11 @@ pub fn journal_enrich(
 }
 
 /// Mine a conversation transcript for experiential moments not yet journaled.
+/// If `segment` is Some, only process that compaction segment of the file.
 pub fn experience_mine(
     store: &mut Store,
     jsonl_path: &str,
+    segment: Option<usize>,
 ) -> Result<usize, String> {
     println!("Experience mining: {}", jsonl_path);
 
@@ -287,7 +316,18 @@ pub fn experience_mine(
         return Ok(0);
     }
 
-    let messages = extract_conversation(jsonl_path)?;
+    let all_messages = extract_conversation(jsonl_path)?;
+
+    // If segment is specified, extract just that segment; otherwise process all messages
+    let messages = match segment {
+        Some(idx) => {
+            let segments = split_on_compaction(all_messages);
+            segments.into_iter().nth(idx)
+                .ok_or_else(|| format!("segment {} out of range", idx))?
+        }
+        None => all_messages,
+    };
+
     let conversation = format_conversation(&messages);
     println!("  {} messages, {} chars", messages.len(), conversation.len());
 
@@ -327,7 +367,13 @@ pub fn experience_mine(
         ("{{KEYS}}", &keys_text),
         ("{{CONVERSATION}}", &conversation),
     ])?;
-    println!("  Prompt: {} chars (~{} tokens)", prompt.len(), prompt.len() / 4);
+    let est_tokens = prompt.len() / 4;
+    println!("  Prompt: {} chars (~{} tokens)", prompt.len(), est_tokens);
+
+    if est_tokens > 150_000 {
+        println!("  Skipping: prompt too large ({} tokens > 150k limit)", est_tokens);
+        return Ok(0);
+    }
 
     println!("  Calling Sonnet...");
     let response = call_sonnet("experience-mine", &prompt)?;
@@ -389,24 +435,34 @@ pub fn experience_mine(
         let _ = store.upsert_node(node);
         count += 1;
 
-        let preview = if content.len() > 80 { &content[..77] } else { content };
+        let preview = if content.len() > 80 {
+            let end = content.floor_char_boundary(77);
+            &content[..end]
+        } else {
+            content
+        };
         println!("  + [{}] {}...", ts, preview);
     }
 
-    // Record this transcript as mined (even if count == 0, to prevent re-runs)
+    // Record this transcript/segment as mined (even if count == 0, to prevent re-runs)
-    // Two keys: content hash (exact dedup) and filename (fast daemon reconcile)
+    let fname_key = match segment {
+        Some(idx) => format!("{}.{}", transcript_filename_key(jsonl_path), idx),
+        None => transcript_filename_key(jsonl_path),
+    };
     let dedup_content = format!("Mined {} ({} entries)", jsonl_path, count);
-    let mut dedup_node = new_node(&dedup_key, &dedup_content);
-    dedup_node.category = store::Category::Task;
-    dedup_node.provenance = store::Provenance::AgentExperienceMine;
-    let _ = store.upsert_node(dedup_node);
-
-    let fname_key = transcript_filename_key(jsonl_path);
     let mut fname_node = new_node(&fname_key, &dedup_content);
     fname_node.category = store::Category::Task;
     fname_node.provenance = store::Provenance::AgentExperienceMine;
     let _ = store.upsert_node(fname_node);
 
+    // For unsegmented calls, also write the content-hash key for backwards compat
+    if segment.is_none() {
+        let mut dedup_node = new_node(&dedup_key, &dedup_content);
+        dedup_node.category = store::Category::Task;
+        dedup_node.provenance = store::Provenance::AgentExperienceMine;
+        let _ = store.upsert_node(dedup_node);
+    }
+
     if count > 0 {
         println!("  Saved {} new journal entries.", count);
     }

src/fact_mine.rs

@@ -234,7 +234,7 @@ pub fn mine_transcript(path: &Path, dry_run: bool) -> Result<Vec<Fact>, String>
     if dry_run {
         for (i, (offset, chunk)) in chunks.iter().enumerate() {
             eprintln!("\n--- Chunk {} (offset {}, {} chars) ---", i + 1, offset, chunk.len());
-            let preview = if chunk.len() > 500 { &chunk[..500] } else { chunk };
+            let preview = if chunk.len() > 500 { &chunk[..chunk.floor_char_boundary(500)] } else { chunk };
             eprintln!("{}", preview);
             if chunk.len() > 500 {
                 eprintln!("  ... ({} more chars)", chunk.len() - 500);

src/main.rs

@@ -952,7 +952,7 @@ fn cmd_experience_mine(args: &[String]) -> Result<(), String> {
     }
 
     let mut store = store::Store::load()?;
-    let count = enrich::experience_mine(&mut store, &jsonl_path)?;
+    let count = enrich::experience_mine(&mut store, &jsonl_path, None)?;
     println!("Done: {} new entries mined.", count);
     Ok(())
 }