engram: expose the geometry so the frame can be verified

engram_scan_nodes_emb_json has existed as a builtin with NO ROUTE. The
embeddings — the actual positions every distance, angle, membership and
grounding is computed from — were unreadable from outside the process.

That is not a missing convenience. It means every claim about the
coordinate frame was unfalsifiable from the API: whether the space is
isotropic, where the centering offset sits, what the origin is, whether a
node carries geometry at all. You cannot verify a coordinate system you
cannot see, and a system whose frame cannot be checked is exactly the
shape this codebase spent 2026-08-16 removing everywhere else.

GET /api/nodes/emb?limit=&offset=. Read-only, paged, no writes.

Measured consequence of having it: the value manifold and the love
component manifold were both decomposed, null-controlled against random
node sets drawn from the same graph, and several published claims were
retracted because the geometry contradicted them. None of that was
possible before this route existed.

engram/src/server.el

@@ -1025,6 +1025,22 @@ fn route_similarity(method: String, path: String, body: String) -> String {
 // nothing on request. NOTE: the offline reify WRITER (engram_geo_reify_store) is
 // currently unwired, so on the live store the resident index is empty and the
 // list returns [] until reification runs — see the cutover report.
+// route_scan_emb — GET /api/nodes/emb?limit=&offset= — read the raw geometry.
+//
+// engram_scan_nodes_emb_json has existed as a builtin with NO ROUTE, so the
+// embeddings — the actual positions every distance, angle, membership and
+// grounding is computed from — were unreadable from outside the process. You
+// cannot verify a coordinate system you cannot see, and every claim about the
+// frame (isotropy, centering, what the origin is) was therefore unfalsifiable
+// from the API. Read-only.
+fn route_scan_emb(method: String, path: String, body: String) -> String {
+    let l_raw: String = query_param(path, "limit")
+    let o_raw: String = query_param(path, "offset")
+    let l: Int = if str_eq(l_raw, "") { 200 } else { str_to_int(l_raw) }
+    let o: Int = if str_eq(o_raw, "") { 0 } else { str_to_int(o_raw) }
+    return engram_scan_nodes_emb_json(l, o)
+}
+
 fn route_neighborhoods(method: String, path: String, body: String) -> String {
     engram_geo_reify_list_json()
 }
@@ -1796,6 +1812,9 @@ fn handle_request(method: String, path: String, body: String) -> String {
     if str_eq(method, "GET") && (str_eq(clean, "/api/edges") || str_eq(clean, "/edges")) {
         return route_scan_edges(method, path, body)
     }
+    if str_eq(method, "GET") && (str_eq(clean, "/api/nodes/emb") || str_eq(clean, "/nodes/emb")) {
+        return route_scan_emb(method, path, body)
+    }
     if str_eq(method, "GET") && str_starts_with(clean, "/api/nodes/") {
         return route_get_node(method, path, body)
     }