docs(session): preserve durable notes on completion

Author: vicary

src/services/session-mcp-runtime.test.ts

@@ -812,6 +812,12 @@ describe("session-mcp-runtime", () => {
         "fully",
         "complete",
         "empty `text`",
+        "trivial",
+        "evergreen",
+        "learnings",
+        "stale facts",
+        "prior sessions",
+        "same-project",
       ]
     ) {
       assertStringIncludes(write, phrase.toLowerCase());

src/services/session-mcp-runtime.ts

@@ -62,11 +62,18 @@ export const SESSION_NOTES_WRITE_DESCRIPTION = [
   "   user. Approaching ~75% context usage counts as stopping mid-task: upsert",
   "   with full detail so a post-compaction agent can resume without",
   "   re-derivation.",
-  "4. **Completing the task** → ONLY when the task is fully done, clear the",
-  "   note BEFORE reporting back. Clearing means deleting it: call this tool",
-  '   with empty `text` and `replace: <id>` (or `replace: "*"` with empty text',
-  "   to clear all notes for this scope). Do not clear a note for a paused,",
-  "   blocked, or partially complete task — upsert per step 3 instead.",
+  "4. **Completing the task** → ONLY when the task is fully done, decide whether",
+  "   the note is merely operational or now contains durable learning. For trivial",
+  "   tasks or no lasting value, clear the note BEFORE reporting back. Clearing",
+  "   means deleting it: call this tool with empty `text` and `replace: <id>`",
+  '   (or `replace: "*"` with empty text to clear all notes for this scope). If',
+  "   the task produced evergreen facts, system details, issue findings, or other",
+  "   learnings that will help future sessions, replace the operational checklist",
+  "   with a concise durable note instead of deleting it. Do not clear a note for",
+  "   a paused, blocked, or partially complete task — upsert per step 3 instead.",
+  "   If `session_search` or `session_notes_read` revealed prior sessions with",
+  "   stale facts, delete those stale note ids too, even when they belong to another",
+  "   same-project root session.",
   "",
   "Also write/update a note:",
   "",