_INSTRUCTIONS told an agent the SessionStart hook was how rules reach a
session, and used that as the argument against a host-memory pointer. The
using-scribe skill said the opposite — pull them yourself, treat any push as a
bonus. Nothing said which wins, and #119 makes these surfaces the
specification, so this was the product behaving two ways.
#2198 is the case that settles it: every plugin hook was silently inert for an
extended period. An agent trusting the push would have run with no binding
rules and no signal, while those rules govern branch, commit and push.
So: _INSTRUCTIONS now leads with the explicit pull and names the hook as a
delivery optimisation. The argument against a host-memory pointer survives —
it never needed the hook to be reliable, because the pull IS the bridge and it
is written into every surface a session already loads.
The static context gains the tiebreaker for the next disagreement: follow the
surface that assumes least about its own delivery. "Most detailed wins" is
wrong precisely because the most detailed surface is the one with a delivery
precondition. It goes there by its own logic — a tiebreaker arriving over MCP
cannot arbitrate what to do when MCP is absent.
Guarded by tests/test_instruction_surfaces_agree.py: every session-start
surface states the pull, and no surface names the push without it. Plugin
version bumped so the cache that executes actually picks the file up (#2209).
Refs #2497
