Claude Code injects only the first ~2,048 chars of an MCP server's
instructions and silently cuts the rest mid-word (#2562, observed live):
_INSTRUCTIONS was 20,002 chars, so ~90% — including all Systems tagging
guidance — never reached any session. Rearchitect delivery around what
each surface actually delivers:
- _INSTRUCTIONS becomes a 1,997-char purpose-sorted map, with a header
comment stating the budget and where detail belongs instead.
- Tool docstrings keep the per-tool HOW (audit: nearly all displaced
topics were already duplicated there); backfill the four gaps —
enter_project session scoping + project bootstrap, create_rule
entity-vs-rule test, create_design_system not-a-rulebook,
create_system two-records test.
- The plugin static context (the delivery floor) gains the
tag-to-Systems reflex and a surfaces-layering statement; plugin
0.1.25 -> 0.1.26 so the executing cache refreshes (#2209).
- create_task / create_note / create_snippet return a systems_hint when
a record is created untagged in a project that has Systems — in-band
at the exact write it applies to, fail-open like the dedup gate.
- Guards: _INSTRUCTIONS length budget, floor-states-the-reflex, and a
displaced-topics sweep asserting every cut topic still lives on a
delivered surface.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
_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