diff --git a/chat.el b/chat.el
index 595a5ad..7d022e5 100644
--- a/chat.el
+++ b/chat.el
@@ -29,9 +29,16 @@ fn engram_numeric_valid(s: String) -> Bool {
     let dot_count: Int = str_len(body) - str_len(no_dot)
     if dot_count > 1 { return false }
     if str_eq(no_dot, "") { return false }
-    // str_to_int on a letter-containing string returns 0; "0" is a valid zero.
+    // str_to_int on a letter-containing string returns 0; "0" and "00..." (e.g. from "0.0")
+    // are valid zeros. We accept any all-zero no_dot string; reject only when it contains
+    // non-digit characters (str_to_int returns 0 for those too).
     let parsed: Int = str_to_int(no_dot)
-    if parsed == 0 && !str_eq(no_dot, "0") { return false }
+    if parsed == 0 {
+        // Verify no_dot is truly all-digit-zeros, not a letter-contaminated string.
+        // Strip all '0' characters; if anything remains the string is non-numeric.
+        let stripped_zeros: String = str_replace(no_dot, "0", "")
+        if !str_eq(stripped_zeros, "") { return false }
+    }
     return true
 }
 
@@ -180,10 +187,16 @@ fn engram_compile(intent: String) -> String {
         } else {
             println("[chat] engram_compile: WARN cold-index — activation and search returned no results for intent=" + str_slice(intent, 0, 60))
         }
-        // Soul-agnostic fallback: search for Persona/Identity nodes by label.
-        let persona_fallback: String = engram_search_json("soul:persona Persona identity", 5)
-        let pf_ok: Bool = !str_eq(persona_fallback, "") && !str_eq(persona_fallback, "[]")
-        let combined: String = if pf_ok { engram_compile_ranked(persona_fallback, 3) } else { "" }
+        // Soul-agnostic fallback: fetch the Persona node by label — immune to cold vector index.
+        // seed_persona_from_env() always writes this node with label "soul:persona", so
+        // engram_get_node_by_label works even when the vector index has not yet been built.
+        // Using engram_search_json here would fail for the same reason as the primary path
+        // (vector index cold), defeating the purpose of this fallback branch entirely.
+        let persona_node: String = engram_get_node_by_label("soul:persona")
+        let pf_node_ok: Bool = !str_eq(persona_node, "") && !str_eq(persona_node, "null")
+        let persona_arr: String = if pf_node_ok { "[" + persona_node + "]" } else { "" }
+        let pf_ok: Bool = pf_node_ok
+        let combined: String = if pf_ok { engram_compile_ranked(persona_arr, 1) } else { "" }
         if str_eq(combined, "") {
             println("[chat] engram_compile: WARN cold-start fallback also empty — LLM has no episodic context")
         }
@@ -431,9 +444,11 @@ fn conv_history_persist(hist: String) -> Void {
     if str_eq(hist, "") { return "" }
     if str_eq(hist, "[]") { return "" }
     // Partial-write guard: refuse to persist a blob that is not a complete JSON array.
-    // A truncated write starting with '[' but missing ']' would overwrite a good node.
+    // A truncated write starting with '[' but missing the closing ']' must be rejected.
+    // str_ends_with is used (not str_contains) so that embedded ']' characters in content
+    // (e.g. "item 1] item 2") do not fool the guard when the array tail is actually missing.
     if !str_starts_with(hist, "[") { return "" }
-    if !str_contains(hist, "]") { return "" }
+    if !str_ends_with(hist, "]") { return "" }
     let tags: String = "[\"conv-history\",\"persistent\"]"
     let node_id: String = engram_node_full(
         hist, "Conversation", "conv:history",
@@ -455,7 +470,7 @@ fn conv_history_load() -> String {
     let label_ok: Bool = !str_eq(label_node, "") && !str_eq(label_node, "null")
     if label_ok {
         let label_content: String = json_get(label_node, "content")
-        let label_valid: Bool = str_starts_with(label_content, "[") && str_contains(label_content, "]")
+        let label_valid: Bool = str_starts_with(label_content, "[") && str_ends_with(label_content, "]")
         if label_valid {
             return label_content
         }
@@ -471,8 +486,9 @@ fn conv_history_load() -> String {
     if str_eq(results, "[]") { return "" }
     let node: String = json_array_get(results, 0)
     let content: String = json_get(node, "content")
-    // Partial-write guard: require both '[' prefix AND ']' presence.
-    if !str_starts_with(content, "[") || !str_contains(content, "]") {
+    // Partial-write guard: require both '[' prefix AND closing ']' at the tail.
+    // str_ends_with guards against embedded ']' in content fooling the check.
+    if !str_starts_with(content, "[") || !str_ends_with(content, "]") {
         println("[chat] conv_history_load: vector search result content invalid — treating as first turn")
         state_set("conv_history_load_failed", "1")
         return ""
@@ -1096,7 +1112,7 @@ fn handle_chat_agentic(body: String) -> String {
     if str_eq(screen_action, "hard_bell") {
         safety_log_bell("hard", json_get(screen_result, "reason"), str_slice(message, 0, 80))
         return "{\"reply\":\"" + json_safe(safety_validate("", "hard_bell")) + "\",\"model\":\"\",\"agentic\":true,\"tools_used\":[]}"
-
+    }
 
     let req_model: String = json_get(body, "model")
     let model: String = if str_eq(req_model, "") { chat_default_model() } else { req_model }