store: strip .md suffix from all keys

Keys were a vestige of the file-based era. resolve_key() added .md
to lookups while upsert() used bare keys, creating phantom duplicate
nodes (the instructions bug: writes went to "instructions", reads
found "instructions.md").

- Remove .md normalization from resolve_key, strip instead
- Update all hardcoded key patterns (journal.md# → journal#, etc)
- Add strip_md_keys() migration to fsck: renames nodes and relations
- Add broken link detection to health report
- Delete redirect table (no longer needed)
- Update config defaults and config.jsonl

Migration: run `poc-memory fsck` to rename existing keys.

Co-Authored-By: ProofOfConcept <poc@bcachefs.org>

src/main.rs

@@ -364,11 +364,11 @@ fn cmd_init() -> Result<(), String> {
     // Initialize store and seed default identity node if empty
     let mut store = store::Store::load()?;
     let count = store.init_from_markdown()?;
-    if !store.nodes.contains_key("identity.md") {
+    if !store.nodes.contains_key("identity") {
         let default_identity = include_str!("../defaults/identity.md");
-        store.upsert("identity.md", default_identity)
+        store.upsert("identity", default_identity)
             .map_err(|e| format!("seed identity: {}", e))?;
-        println!("Seeded identity.md in store");
+        println!("Seeded identity in store");
     }
     store.save()?;
     println!("Indexed {} memory units", count);
@@ -413,7 +413,25 @@ fn cmd_migrate() -> Result<(), String> {
 }
 
 fn cmd_fsck() -> Result<(), String> {
-    store::fsck()
+    store::fsck()?;
+    store::strip_md_keys()?;
+
+    // Check for broken links
+    let store = store::Store::load()?;
+    let mut orphans = 0usize;
+    for rel in &store.relations {
+        if rel.deleted { continue; }
+        if !store.nodes.contains_key(&rel.source_key)
+            || !store.nodes.contains_key(&rel.target_key) {
+            orphans += 1;
+        }
+    }
+    if orphans > 0 {
+        eprintln!("{} broken links (run `health` for details)", orphans);
+    } else {
+        eprintln!("No broken links");
+    }
+    Ok(())
 }
 
 fn cmd_health() -> Result<(), String> {
@@ -1582,7 +1600,12 @@ fn cmd_history(args: &[String]) -> Result<(), String> {
     };
 
     let full = parsed.full;
-    let key = parsed.key.join(" ");
+    let raw_key = parsed.key.join(" ");
+
+    // Resolve key consistently with render/write
+    let store = store::Store::load()?;
+    let key = store.resolve_key(&raw_key).unwrap_or(raw_key);
+    drop(store);
 
     // Replay the node log, collecting all versions of this key
     let path = store::nodes_path();
@@ -1650,7 +1673,7 @@ fn cmd_write(args: &[String]) -> Result<(), String> {
         return Err("Usage: poc-memory write KEY < content\n\
                     Reads content from stdin, upserts into the store.".into());
     }
-    let key = args.join(" ");
+    let raw_key = args.join(" ");
     let mut content = String::new();
     std::io::Read::read_to_string(&mut std::io::stdin(), &mut content)
         .map_err(|e| format!("read stdin: {}", e))?;
@@ -1660,6 +1683,9 @@ fn cmd_write(args: &[String]) -> Result<(), String> {
     }
 
     let mut store = store::Store::load()?;
+    // Resolve the key the same way render/search do, so writes and reads
+    // always hit the same node.  Fall back to raw key for new nodes.
+    let key = store.resolve_key(&raw_key).unwrap_or(raw_key);
     let result = store.upsert(&key, &content)?;
     match result {
         "unchanged" => println!("No change: '{}'", key),
@@ -1721,12 +1747,8 @@ fn cmd_export(args: &[String]) -> Result<(), String> {
         return Err("Usage: poc-memory export FILE [FILE...] | --all".into());
     } else {
         args.iter().map(|a| {
-            // If it doesn't end in .md, try resolving
-            if a.ends_with(".md") {
-                a.clone()
-            } else {
-                format!("{}.md", a)
-            }
+            // Strip .md if user supplied it — store keys are bare
+            a.strip_suffix(".md").unwrap_or(a).to_string()
         }).collect()
     };
 
@@ -1735,7 +1757,7 @@ fn cmd_export(args: &[String]) -> Result<(), String> {
     for file_key in &targets {
         match store.export_to_markdown(file_key) {
             Some(content) => {
-                let out_path = mem_dir.join(file_key);
+                let out_path = mem_dir.join(format!("{}.md", file_key));
                 std::fs::write(&out_path, &content)
                     .map_err(|e| format!("write {}: {}", out_path.display(), e))?;
                 let section_count = content.matches("<!-- mem:").count() + 1;
@@ -1767,7 +1789,7 @@ fn cmd_journal_write(args: &[String]) -> Result<(), String> {
         .join("-");
     let slug = if slug.len() > 50 { &slug[..50] } else { &slug };
 
-    let key = format!("journal.md#j-{}-{}", timestamp.to_lowercase().replace(':', "-"), slug);
+    let key = format!("journal#j-{}-{}", timestamp.to_lowercase().replace(':', "-"), slug);
 
     // Build content with header
     let content = format!("## {}\n\n{}", timestamp, text);
@@ -1891,7 +1913,6 @@ fn journal_tail_digests(store: &store::Store, prefix: &str, n: usize, full: bool
     let skip = if digests.len() > n { digests.len() - n } else { 0 };
     for node in digests.iter().skip(skip) {
         let label = node.key.strip_prefix(prefix)
-            .and_then(|s| s.strip_suffix(".md"))
             .unwrap_or(&node.key);
         let title = extract_title(&node.content);
         if full {
@@ -1959,7 +1980,7 @@ fn cmd_query(args: &[String]) -> Result<(), String> {
 Expressions:\n  \
   degree > 15                          property filter\n  \
   key ~ 'journal.*' AND degree > 10    boolean + regex\n  \
-  neighbors('identity.md') WHERE ...   graph traversal\n  \
+  neighbors('identity') WHERE ...   graph traversal\n  \
   community_id = community('key')      function as value\n  \
   *                                    all nodes\n\n\
 Pipe stages:\n  \