agentic-sx Phase 3: trace — console output as attached CID objects (TDD)

Per-agent buffer = persist append-only log stream + kv drain cursor;
commit-with-trace! drains everything-since-last-commit into a console-trace
object and binds it git-note style (ref notes/trace/<commit-cid> -> trace
cid). Trace never enters the commit tree; binding is a re-bindable ref layer
over immutable objects; failed commits keep the buffer; plain commit! leaves
binding to the agent. 35/35 (153/153 total).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/agentic/trace.sx

@@ -0,0 +1,136 @@
+; lib/agentic/trace.sx — agentic-sx Phase 3: console traces as ATTACHED
+; content-addressed objects. An agent's console/tool output accumulates in a
+; per-agent append-only persist log stream; the commit verb drains everything
+; since the last commit into a console-trace object and binds it to the new
+; commit git-note style: ref "notes/trace/<commit-cid>" -> trace cid. The
+; trace is NOT in the commit's tree — attaching never changes the commit cid,
+; and the note is a re-bindable ref layer over immutable objects.
+; Granularity = the commit, agent-chosen: whatever was logged since the last
+; drain travels with the next commit.
+; Requires: lib/agentic/branch.sx (and its deps).
+
+; ---- buffer stream + drain cursor (namespaced under the repo prefix) ----
+(define
+  agentic/trace-stream
+  (fn
+    (sp agent)
+    (str (get (agentic/space-repo sp) :prefix) "/trace/" agent)))
+
+(define
+  agentic/trace-cursor-key
+  (fn
+    (sp agent)
+    (str (get (agentic/space-repo sp) :prefix) "/trace-cursor/" agent)))
+
+; append one console/tool entry to the agent's buffer => true
+(define
+  agentic/trace!
+  (fn
+    (sp agent kind text)
+    (begin
+      (persist/append
+        (git/repo-db (agentic/space-repo sp))
+        (agentic/trace-stream sp agent)
+        "trace-entry"
+        0
+        (agentic/trace-entry kind text))
+      true)))
+
+; entries logged since the last drain, oldest first
+(define
+  agentic/trace-pending
+  (fn
+    (sp agent)
+    (let
+      ((db (git/repo-db (agentic/space-repo sp))))
+      (let
+        ((cur (persist/kv-get db (agentic/trace-cursor-key sp agent))))
+        (map
+          (fn (e) (persist/event-data e))
+          (persist/read-from
+            db
+            (agentic/trace-stream sp agent)
+            (+ (if (nil? cur) 0 cur) 1)))))))
+
+; advance the drain cursor to the stream's high-water mark
+(define
+  agentic/trace-mark!
+  (fn
+    (sp agent)
+    (let
+      ((db (git/repo-db (agentic/space-repo sp))))
+      (begin
+        (persist/kv-put
+          db
+          (agentic/trace-cursor-key sp agent)
+          (persist/last-seq db (agentic/trace-stream sp agent)))
+        true))))
+
+; ---- git-note-style binding: commit cid -> trace cid ----
+(define
+  agentic/trace-note-ref
+  (fn (commit-cid) (str "notes/trace/" commit-cid)))
+
+; write the trace object and bind it to the commit => trace cid | {:error}
+(define
+  agentic/attach-trace!
+  (fn
+    (sp commit-cid trace-obj)
+    (let
+      ((repo (agentic/space-repo sp)))
+      (if
+        (not (agentic/console-trace? trace-obj))
+        {:error "not-a-console-trace"}
+        (let
+          ((tcid (git/write repo trace-obj)))
+          (begin
+            (git/ref-set! repo (agentic/trace-note-ref commit-cid) tcid)
+            tcid))))))
+
+(define
+  agentic/trace-cid-for
+  (fn
+    (sp commit-cid)
+    (git/ref-get (agentic/space-repo sp) (agentic/trace-note-ref commit-cid))))
+
+(define
+  agentic/trace-for
+  (fn
+    (sp commit-cid)
+    (let
+      ((tcid (agentic/trace-cid-for sp commit-cid)))
+      (if (nil? tcid) nil (git/read (agentic/space-repo sp) tcid)))))
+
+; ---- the commit verb with trace binding ----
+; commit! then drain the buffer into an attached console-trace.
+; => {:cid cid :trace tcid} | {:cid cid} when nothing was logged
+;  | commit!'s {:error ...}/{:conflict ...} passthrough (buffer kept)
+(define
+  agentic/commit-with-trace!
+  (fn
+    (sp agent kind files meta)
+    (let
+      ((cid (agentic/commit! sp agent kind files meta)))
+      (if
+        (dict? cid)
+        cid
+        (let
+          ((entries (agentic/trace-pending sp agent)))
+          (if
+            (= (len entries) 0)
+            {:cid cid}
+            (let
+              ((tcid (agentic/attach-trace! sp cid (agentic/console-trace entries {:agent agent :commit cid}))))
+              (begin (agentic/trace-mark! sp agent) {:trace tcid :cid cid}))))))))
+
+; (commit-cid trace-cid) pairs for the agent's session, newest first,
+; commits without a bound trace omitted
+(define
+  agentic/session-traces
+  (fn
+    (sp agent)
+    (filter
+      (fn (p) (not (nil? (nth p 1))))
+      (map
+        (fn (cid) (list cid (agentic/trace-cid-for sp cid)))
+        (agentic/session-log sp agent)))))