docs(analysis): evaluate a Claude Code plugin as a fourth transport

deploy/harbor/inspect_transcript.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Structural probe: does a Claude Code transcript carry the request prefix?
+
+Answers one question for the keepalive analysis — can a plugin reconstruct the
+byte-exact `tools` + `system` + `messages` a cache-read ping must reproduce?
+Prints only structure (keys, record types, counts), never content.
+"""
+import json
+import sys
+from collections import Counter
+
+path = sys.argv[1]
+keys = set()
+types = Counter()
+roles = Counter()
+sys_hits = set()
+tool_hits = set()
+
+for line in open(path):
+    line = line.strip()
+    if not line:
+        continue
+    try:
+        d = json.loads(line)
+    except Exception:
+        continue
+    if not isinstance(d, dict):
+        continue
+    keys |= set(d.keys())
+    types[d.get("type")] += 1
+    msg = d.get("message")
+    if isinstance(msg, dict):
+        roles[msg.get("role")] += 1
+        for k in msg:
+            if "system" in k.lower():
+                sys_hits.add("message." + k)
+            if "tool" in k.lower():
+                tool_hits.add("message." + k)
+    for k in d:
+        if "system" in k.lower():
+            sys_hits.add(k)
+        if "tool" in k.lower():
+            tool_hits.add(k)
+
+print("record types:      ", dict(types))
+print("message roles:     ", dict(roles))
+print("top-level keys:    ", sorted(keys))
+print("system-ish keys:   ", sorted(sys_hits) or "NONE")
+print("tool-schema-ish:   ", sorted(tool_hits) or "NONE")