docs(ai): require an epoch on the tail of helper-agent ids

A helper agent's session-context file is .ai/session-context.d/<id>.org. A bare, reused id like "codex" makes the next run resolve to the previous run's leftover anchor, which it then mistakes for a crash to recover or clobbers. That bit on 2026-06-13: a codex run left codex.org for the next session to clean up.

The fix is a convention, not a resolver change. The spawner appends an epoch on the tail (host.project.runtime.<epoch>) so each run gets a fresh anchor. The epoch can't be minted inside session-context-path, since that resolver runs many times per session and must return the same path each call. I documented it in protocols.org, the wrap-up recommended-shape note, and the resolver header.

1 files changed, 8 insertions, 0 deletions

diff --git a/.ai/scripts/session-context-path b/.ai/scripts/session-context-path
index 8cc56f6..670a610 100755
--- a/.ai/scripts/session-context-path
+++ b/.ai/scripts/session-context-path
@@ -10,6 +10,14 @@
 # instead of clobbering the singleton. The id is sanitized to filename-safe
 # characters so a stray value can't escape the .d/ directory.
 #
+# The id must be unique per run; the spawner appends an epoch on the tail
+# (recommended shape host.project.runtime.<epoch>) so a re-run of the same
+# logical agent gets a fresh anchor instead of resolving to a prior run's
+# leftover. The epoch is never minted here: this resolver is called many times
+# per session and must return the same path each call, so it can't generate a
+# new value. See protocols.org "Agent-scoped path". A bare, reused id (just
+# "codex") is the bug that motivated this note.
+#
 # Workflows call this to resolve the path; both startup (existence check) and
 # wrap-up (rename source) read/write through it. Callers should fall back to
 # .ai/session-context.org if this script isn't present yet (older checkouts