observation: use transcript progress log, mark after success

Wire select_conversation_fragments to use store.is_segment_mined()
instead of scanning _observed-transcripts stub nodes. Segments are
now marked AFTER the agent succeeds (via mark_observation_done),
not before — so failed runs don't lose segments.

Fragment IDs flow through the Resolved.keys → AgentBatch.node_keys
path so run_and_apply_with_log can mark them post-success.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/agents/knowledge.rs

@@ -634,6 +634,11 @@ pub fn run_and_apply_with_log(
             log(&format!("skipped: {}", desc));
         }
     }
+    // Mark conversation segments as mined after successful processing
+    if agent_name == "observation" {
+        mark_observation_done(&result.node_keys);
+    }
+
     Ok((actions.len(), applied))
 }
 
@@ -699,16 +704,17 @@ pub fn run_one_agent(
 // Conversation fragment selection
 // ---------------------------------------------------------------------------
 
-/// Extract human-readable dialogue from a conversation JSONL
-const OBSERVED_PREFIX: &str = "_observed-transcripts";
-
 /// Select conversation fragments (per-segment) for the observation extractor.
-/// Skips segments already processed, marks selected segments as observed.
+/// Uses the transcript-progress.capnp log for dedup — no stub nodes.
+/// Does NOT pre-mark segments; caller must call mark_observation_done() after success.
 pub fn select_conversation_fragments(n: usize) -> Vec<(String, String)> {
     let projects = crate::config::get().projects_dir.clone();
     if !projects.exists() { return Vec::new(); }
 
-    let observed = super::enrich::keys_with_prefix(&format!("{}-", OBSERVED_PREFIX));
+    let store = match crate::store::Store::load() {
+        Ok(s) => s,
+        Err(_) => return Vec::new(),
+    };
 
     let mut jsonl_files: Vec<PathBuf> = Vec::new();
     if let Ok(dirs) = fs::read_dir(&projects) {
@@ -729,43 +735,50 @@ pub fn select_conversation_fragments(n: usize) -> Vec<(String, String)> {
         }
     }
 
-    // Collect unmined segments across all transcripts, keeping the text
-    let mut candidates: Vec<(PathBuf, usize, String, String)> = Vec::new();
+    // Collect unmined segments across all transcripts
+    let mut candidates: Vec<(String, String)> = Vec::new();
     for path in &jsonl_files {
-        for (seg_idx, messages) in super::enrich::unmined_segments(path, OBSERVED_PREFIX, &observed) {
-            let text = format_segment(&messages, 8000);
+        let path_str = path.to_string_lossy();
+        let messages = match super::enrich::extract_conversation(&path_str) {
+            Ok(m) => m,
+            Err(_) => continue,
+        };
+        let session_id = path.file_stem()
+            .map(|s| s.to_string_lossy().to_string())
+            .unwrap_or_else(|| "unknown".into());
+
+        let segments = super::enrich::split_on_compaction(messages);
+        for (seg_idx, segment) in segments.into_iter().enumerate() {
+            if store.is_segment_mined(&session_id, seg_idx as u32, "observation") {
+                continue;
+            }
+            let text = format_segment(&segment, 8000);
             if text.len() > 500 {
-                let session_id = path.file_stem()
-                    .map(|s| s.to_string_lossy().to_string())
-                    .unwrap_or_else(|| "unknown".into());
                 let id = format!("{}.{}", session_id, seg_idx);
-                candidates.push((path.clone(), seg_idx, id, text));
+                candidates.push((id, text));
+            }
+        }
+
+        if candidates.len() >= n { break; }
+    }
+
+    candidates.truncate(n);
+    candidates
+}
+
+/// Mark observation segments as successfully mined (call AFTER the agent succeeds).
+pub fn mark_observation_done(fragment_ids: &[String]) {
+    let mut store = match crate::store::Store::load() {
+        Ok(s) => s,
+        Err(_) => return,
+    };
+    for id in fragment_ids {
+        if let Some((session_id, seg_str)) = id.rsplit_once('.') {
+            if let Ok(seg) = seg_str.parse::<u32>() {
+                let _ = store.mark_segment_mined(session_id, seg, "observation");
             }
         }
     }
-
-    // Take up to n, mark them, and return the text
-    let selected: Vec<_> = candidates.into_iter().take(n).collect();
-
-    if !selected.is_empty() {
-        if let Ok(mut store) = crate::store::Store::load() {
-            for (path, seg_idx, _, _) in &selected {
-                super::enrich::mark_segment(
-                    &mut store,
-                    &path.to_string_lossy(),
-                    OBSERVED_PREFIX,
-                    *seg_idx,
-                    "agent:knowledge-observation",
-                    "observed",
-                );
-            }
-            let _ = store.save();
-        }
-    }
-
-    selected.into_iter()
-        .map(|(_, _, id, text)| (id, text))
-        .collect()
 }
 
 /// Format a segment's messages into readable text for the observation agent.