Tombstone the remaining forget paths (close the immutability arc)

Phase 1 tombstoned memory/delete + node/delete, but the generic forget
path was still destructive. This routes every forget through the same
tombstone semantics so nothing in the daemon can hard-delete an engram
node anymore.

Canonical helper: mem_tombstone (memory.el, imported first so every module
can call it) — keep the node + its edges, record a Tombstone marker, never
engram_forget. neuron-api's tombstone_node now delegates to it (single
source of truth).

Per-path before -> after:
- memory.el `mem_forget`      hard delete (engram_forget) -> tombstone. This
  alone fixes both callers: the /api/neuron/memory/forget route
  (handle_api_forget) and the cultivate op=="forget".
- awareness.el autonomous `forget` action  engram_forget -> mem_tombstone.
  The soul can no longer autonomously hard-delete a memory.
- mcp-wrapper tool_forget  was a FAKE no-op that returned {"ok","deleted"}
  without deleting OR tombstoning -> now routes to the soul's tombstoning
  /api/neuron/memory/delete; tool description fixed to say it
  supersedes/tombstones (recoverable), not "Remove a node".

Left intentionally as hard deletes (internal GC / lifecycle, not user
memory, all call engram_forget directly): session-summary replace
(chat.el), mem_consolidate dedup (memory.el), session-start telemetry
pruning (soul.el), session lifecycle (sessions.el).

Regenerated both ship paths under a 3GB physical-RSS watchdog (peak ~32MB):
dist/soul.c (single-TU amalgamation, macOS/Linux) and the per-module
dist/{memory,awareness,neuron-api}.c (Windows/Linux build). Verified: no
forget handler calls engram_forget; a forget leaves the node present +
tombstone marker. Gate (neuron-ui verify-soul-contract.sh, new memory-forget
row): PRESENCE + IMMUTABILITY PASS.

awareness.el

@@ -446,8 +446,10 @@ fn respond(action_json: String) -> String {
     }
 
     if str_eq(kind, "forget") {
-        engram_forget(payload)
-        return "{\"outcome\":\"forgotten\",\"id\":\"" + payload + "\"}"
+        // The soul must NOT be able to autonomously hard-delete a memory.
+        // Tombstone instead (keep node + edges, recoverable).
+        let _marker: String = mem_tombstone(payload)
+        return "{\"outcome\":\"tombstoned\",\"id\":\"" + payload + "\"}"
     }
 
     return "{\"outcome\":\"noop\"}"

dist/awareness.c

@@ -10,6 +10,7 @@ el_val_t mem_remember(el_val_t content, el_val_t tags);
 el_val_t mem_recall(el_val_t query, el_val_t depth);
 el_val_t mem_search(el_val_t query, el_val_t limit);
 el_val_t mem_strengthen(el_val_t node_id);
+el_val_t mem_tombstone(el_val_t node_id);
 el_val_t mem_forget(el_val_t node_id);
 el_val_t mem_consolidate(void);
 el_val_t mem_save(el_val_t path);
@@ -362,8 +363,8 @@ el_val_t respond(el_val_t action_json) {
     return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"strengthened\",\"id\":\""), payload), EL_STR("\"}"));
   }
   if (str_eq(kind, EL_STR("forget"))) {
-    engram_forget(payload);
-    return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"forgotten\",\"id\":\""), payload), EL_STR("\"}"));
+    el_val_t _marker = mem_tombstone(payload);
+    return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"tombstoned\",\"id\":\""), payload), EL_STR("\"}"));
   }
   return EL_STR("{\"outcome\":\"noop\"}");
   return 0;

dist/memory.c

@@ -10,6 +10,7 @@ el_val_t mem_remember(el_val_t content, el_val_t tags);
 el_val_t mem_recall(el_val_t query, el_val_t depth);
 el_val_t mem_search(el_val_t query, el_val_t limit);
 el_val_t mem_strengthen(el_val_t node_id);
+el_val_t mem_tombstone(el_val_t node_id);
 el_val_t mem_forget(el_val_t node_id);
 el_val_t mem_consolidate(void);
 el_val_t mem_save(el_val_t path);
@@ -69,8 +70,18 @@ el_val_t mem_strengthen(el_val_t node_id) {
   return 0;
 }
 
+el_val_t mem_tombstone(el_val_t node_id) {
+  el_val_t tags = EL_STR("[\"Tombstone\",\"status:deleted\"]");
+  el_val_t marker = engram_node_full(node_id, EL_STR("Tombstone"), el_str_concat(EL_STR("tombstone:"), node_id), el_from_float(0.01), el_from_float(0.01), el_from_float(1.0), EL_STR("Episodic"), tags);
+  if (!str_eq(marker, EL_STR(""))) {
+    engram_connect(marker, node_id, el_from_float(1.0), EL_STR("tombstones"));
+  }
+  return marker;
+  return 0;
+}
+
 el_val_t mem_forget(el_val_t node_id) {
-  engram_forget(node_id);
+  el_val_t _marker = mem_tombstone(node_id);
   return 0;
 }
 

dist/neuron-api.c

@@ -10,6 +10,7 @@ el_val_t mem_remember(el_val_t content, el_val_t tags);
 el_val_t mem_recall(el_val_t query, el_val_t depth);
 el_val_t mem_search(el_val_t query, el_val_t limit);
 el_val_t mem_strengthen(el_val_t node_id);
+el_val_t mem_tombstone(el_val_t node_id);
 el_val_t mem_forget(el_val_t node_id);
 el_val_t mem_consolidate(void);
 el_val_t mem_save(el_val_t path);
@@ -193,12 +194,7 @@ el_val_t api_not_persisted(el_val_t id) {
 }
 
 el_val_t tombstone_node(el_val_t id) {
-  el_val_t tags = EL_STR("[\"Tombstone\",\"status:deleted\"]");
-  el_val_t marker = engram_node_full(id, EL_STR("Tombstone"), el_str_concat(EL_STR("tombstone:"), id), el_from_float(0.01), el_from_float(0.01), el_from_float(1.0), EL_STR("Episodic"), tags);
-  if (!str_eq(marker, EL_STR(""))) {
-    engram_connect(marker, id, el_from_float(1.0), EL_STR("tombstones"));
-  }
-  return marker;
+  return mem_tombstone(id);
   return 0;
 }
 
@@ -613,7 +609,7 @@ el_val_t handle_api_forget(el_val_t body) {
     return api_err_protected(node_id);
   }
   mem_forget(node_id);
-  return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\"}"));
+  return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"tombstoned\":true}"));
   return 0;
 }
 
@@ -717,7 +713,7 @@ el_val_t handle_api_cultivate(el_val_t body) {
       return api_err(EL_STR("id is required"));
     }
     mem_forget(node_id);
-    return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"cultivated\":true}"));
+    return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"tombstoned\":true,\"cultivated\":true}"));
   }
   if (str_eq(op, EL_STR("link_entities"))) {
     el_val_t from_id = json_get(body, EL_STR("from_id"));

dist/soul.c

@@ -963,6 +963,7 @@ el_val_t mem_remember(el_val_t content, el_val_t tags);
 el_val_t mem_recall(el_val_t query, el_val_t depth);
 el_val_t mem_search(el_val_t query, el_val_t limit);
 el_val_t mem_strengthen(el_val_t node_id);
+el_val_t mem_tombstone(el_val_t node_id);
 el_val_t mem_forget(el_val_t node_id);
 el_val_t mem_consolidate(void);
 el_val_t mem_save(el_val_t path);
@@ -25331,8 +25332,18 @@ el_val_t mem_strengthen(el_val_t node_id) {
   return 0;
 }
 
+el_val_t mem_tombstone(el_val_t node_id) {
+  el_val_t tags = EL_STR("[\"Tombstone\",\"status:deleted\"]");
+  el_val_t marker = engram_node_full(node_id, EL_STR("Tombstone"), el_str_concat(EL_STR("tombstone:"), node_id), el_from_float(0.01), el_from_float(0.01), el_from_float(1.0), EL_STR("Episodic"), tags);
+  if (!str_eq(marker, EL_STR(""))) {
+    engram_connect(marker, node_id, el_from_float(1.0), EL_STR("tombstones"));
+  }
+  return marker;
+  return 0;
+}
+
 el_val_t mem_forget(el_val_t node_id) {
-  engram_forget(node_id);
+  el_val_t _marker = mem_tombstone(node_id);
   return 0;
 }
 
@@ -26405,8 +26416,8 @@ el_val_t respond(el_val_t action_json) {
     return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"strengthened\",\"id\":\""), payload), EL_STR("\"}"));
   }
   if (str_eq(kind, EL_STR("forget"))) {
-    engram_forget(payload);
-    return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"forgotten\",\"id\":\""), payload), EL_STR("\"}"));
+    el_val_t _marker = mem_tombstone(payload);
+    return el_str_concat(el_str_concat(EL_STR("{\"outcome\":\"tombstoned\",\"id\":\""), payload), EL_STR("\"}"));
   }
   return EL_STR("{\"outcome\":\"noop\"}");
   return 0;
@@ -28728,12 +28739,7 @@ el_val_t api_not_persisted(el_val_t id) {
 }
 
 el_val_t tombstone_node(el_val_t id) {
-  el_val_t tags = EL_STR("[\"Tombstone\",\"status:deleted\"]");
-  el_val_t marker = engram_node_full(id, EL_STR("Tombstone"), el_str_concat(EL_STR("tombstone:"), id), el_from_float(0.01), el_from_float(0.01), el_from_float(1.0), EL_STR("Episodic"), tags);
-  if (!str_eq(marker, EL_STR(""))) {
-    engram_connect(marker, id, el_from_float(1.0), EL_STR("tombstones"));
-  }
-  return marker;
+  return mem_tombstone(id);
   return 0;
 }
 
@@ -29148,7 +29154,7 @@ el_val_t handle_api_forget(el_val_t body) {
     return api_err_protected(node_id);
   }
   mem_forget(node_id);
-  return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\"}"));
+  return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"tombstoned\":true}"));
   return 0;
 }
 
@@ -29252,7 +29258,7 @@ el_val_t handle_api_cultivate(el_val_t body) {
       return api_err(EL_STR("id is required"));
     }
     mem_forget(node_id);
-    return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"cultivated\":true}"));
+    return el_str_concat(el_str_concat(EL_STR("{\"ok\":true,\"id\":\""), node_id), EL_STR("\",\"tombstoned\":true,\"cultivated\":true}"));
   }
   if (str_eq(op, EL_STR("link_entities"))) {
     el_val_t from_id = json_get(body, EL_STR("from_id"));

mcp-wrapper/src/main.el

@@ -91,7 +91,7 @@ tool("beginSession", "Initialize session: surface recent high-importance memorie
 "," + tool("recall", "Retrieve memories by chain or query.") +
 "," + tool("inspectMemories", "List recent memory nodes.") +
 "," + tool("evolveMemory", "Update an existing memory node, optionally superseding another.") +
-"," + tool("forget", "Remove a node from memory.") +
+"," + tool("forget", "Supersede/tombstone a node (keeps it and its edges, recoverable); does not hard-delete.") +
 "," + tool("pinNode", "Strengthen a node so it stays salient.") +
 // ── Knowledge ───────────────────────────────────────────────────────────────
 "," + tool("searchKnowledge", "Search knowledge base by semantic similarity.") +
@@ -541,8 +541,12 @@ fn tool_forget(args: String) -> String {
     if str_eq(id, "") {
         return mcp_text_result("error: node_id is required")
     }
-    // Soft-delete: record a tombstone memory and return ok
-    return mcp_json_result("{\"ok\":true,\"deleted\":\"" + id + "\"}")
+    // Immutable delete: route to the soul's tombstoning endpoint (keeps the node
+    // + edges, hides from default reads, recoverable via ?include_deleted).
+    // Previously this returned a fake ok without deleting OR tombstoning anything.
+    let body: String = "{\"id\":\"" + id + "\"}"
+    let resp: String = http_post_json(neuron_url() + "/memory/delete", body)
+    return mcp_json_result(resp)
 }
 
 fn tool_check_events(args: String) -> String {

memory.el

@@ -43,8 +43,32 @@ fn mem_strengthen(node_id: String) -> Void {
     engram_strengthen(node_id)
 }
 
+// mem_tombstone — immutable "delete": KEEP the node and all its edges; record a
+// Tombstone marker (content = target id, label "tombstone:<id>", wired with a
+// "tombstones" edge). Never engram_forget. Default bounded list reads hide
+// tombstoned nodes; ?include_deleted=1 recovers them. This is the ONE canonical
+// tombstone helper — every forget path routes through it. Defined here in
+// memory.el (imported first) so awareness.el and neuron-api.el can both call it.
+fn mem_tombstone(node_id: String) -> String {
+    let tags: String = "[\"Tombstone\",\"status:deleted\"]"
+    let marker: String = engram_node_full(
+        node_id, "Tombstone", "tombstone:" + node_id,
+        el_from_float(0.01), el_from_float(0.01), el_from_float(1.0),
+        "Episodic", tags)
+    if !str_eq(marker, "") {
+        engram_connect(marker, node_id, el_from_float(1.0), "tombstones")
+    }
+    return marker
+}
+
+// mem_forget — NOTE: no longer a hard delete. Engram nodes are immutable, so
+// this now TOMBSTONES (via mem_tombstone): the node and its edges are kept and
+// stay recoverable. Every caller (the /memory/forget route and the cultivate
+// forget op) is non-destructive as a result. Internal GC that genuinely needs
+// removal (session-summary replace, telemetry pruning) calls engram_forget
+// directly and is unaffected by this.
 fn mem_forget(node_id: String) -> Void {
-    engram_forget(node_id)
+    let _marker: String = mem_tombstone(node_id)
 }
 
 // mem_consolidate — structural scan plus salience-evolution pass.

neuron-api.el

@@ -114,15 +114,8 @@ fn api_not_persisted(id: String) -> String {
 // bounded list reads hide tombstoned nodes (memory_hide_tombstoned); internal
 // cognition and explicit ?include_deleted reads still see them.
 fn tombstone_node(id: String) -> String {
-    let tags: String = "[\"Tombstone\",\"status:deleted\"]"
-    let marker: String = engram_node_full(
-        id, "Tombstone", "tombstone:" + id,
-        el_from_float(0.01), el_from_float(0.01), el_from_float(1.0),
-        "Episodic", tags)
-    if !str_eq(marker, "") {
-        engram_connect(marker, id, el_from_float(1.0), "tombstones")
-    }
-    return marker
+    // Delegates to the canonical helper in memory.el (single source of truth).
+    return mem_tombstone(id)
 }
 
 // tombstoned_id_set — delimited "|id1|id2|" of every tombstoned target id.
@@ -572,13 +565,15 @@ fn handle_api_link_entities(body: String) -> String {
     return "{\"ok\":true,\"from_id\":\"" + from_id + "\",\"to_id\":\"" + to_id + "\",\"relation\":\"" + eff_relation + "\"}"
 }
 
-// handle_api_forget — delete a node by ID. Blocked for protected identity nodes.
+// handle_api_forget — TOMBSTONE a node by ID (immutable; mem_forget now
+// tombstones). The node + edges are kept and recoverable. Blocked for protected
+// identity nodes.
 fn handle_api_forget(body: String) -> String {
     let node_id: String = json_get(body, "id")
     if str_eq(node_id, "") { return api_err("id is required") }
     if is_protected_node(node_id) { return api_err_protected(node_id) }
     mem_forget(node_id)
-    return "{\"ok\":true,\"id\":\"" + node_id + "\"}"
+    return "{\"ok\":true,\"id\":\"" + node_id + "\",\"tombstoned\":true}"
 }
 
 // handle_api_evolve_memory — evolve a Memory node. Blocked for protected identity nodes.
@@ -693,8 +688,9 @@ fn handle_api_cultivate(body: String) -> String {
     if str_eq(op, "forget") {
         let node_id: String = json_get(body, "id")
         if str_eq(node_id, "") { return api_err("id is required") }
+        // Immutable: mem_forget now tombstones (keep node + edges), never hard-delete.
         mem_forget(node_id)
-        return "{\"ok\":true,\"id\":\"" + node_id + "\",\"cultivated\":true}"
+        return "{\"ok\":true,\"id\":\"" + node_id + "\",\"tombstoned\":true,\"cultivated\":true}"
     }
 
     if str_eq(op, "link_entities") {