feat(retrieval): the ledger records what was OPENED, not merely what was shown (#4100)

Milestone 386 made a repeat REFERENCED rather than withheld, and the line it
chose says "You saw it earlier this session". Nothing ever checked that. The
arms emit a TEASER — title, trigger, get_rule(N) — so a session can be shown a
rule twenty times and never read a word of it, and a compaction summarises the
teaser away leaving nothing behind. The server was asserting something about
the reader's context it had no way to know.

Three states now, where there were two:

  never surfaced   "it is not in this session's loaded set"
  named, unopened  "Mentioned earlier this session but not opened — read it…"
  opened           "You opened it earlier this session; pull it… again"

The middle one is the honest one and the one that was missing. It keeps the
full invitation, because a session that skipped a teaser is in nearly the
position of one never shown it.

HOW "OPENED" BECOMES OBSERVABLE. A new PostToolUse hook watches the get_rule
call itself and appends to `<sid>.opened.ids`. PostToolUse does fire for MCP
tools — the event's own output schema carries `updatedMCPToolOutput`, which
would be meaningless otherwise — and the matcher is `mcp__.*__get_rule` so the
server segment, which varies by install, is not pinned.

This is NOT the self-report 386 rejected. That objection was to ASKING a model
whether it holds a rule, which is unverifiable. A tool call is an event the
harness reports whether anyone asks. Recording what a session DID and believing
what it SAYS about itself are different kinds of evidence.

Both ledgers clear together on compact/clear. Keeping `.opened.ids` across a
compaction would have the arms telling a freshly-summarised session "you opened
it earlier" about a rule now nowhere in its context — a more confident version
of the bug being removed. Same reader (scribe_rules_live) for both, so ageing,
last-entry-wins and the bare-id format are defined once.

Also closes two smoke-coverage holes the checker was reporting as SKIP: the new
recorder, and scribe_precompact_preserve.sh from #3680. The latter needed
STATIC_FLOOR to become a set — PreCompact's contract is inverted, its stdout
BECOMES the summarizer's instructions, so silence is its failure mode and a
generic read of it looks like a leak.

Step 2 of milestone 416, and a hard prerequisite for step 4: while suppression
keys on shown, widening k marks records "seen" faster than they are read, and
the ledger would degrade in proportion to the improvement.

Plugin minted 2026.09.16.1232 -> 2026.09.16.2102.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe for Claude Code: connects the scribe MCP server, adds the hooks that deliver live project state and relevant records at the right moment, ships the shared client-neutral Scribe skills (using-scribe, writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code, shape-accounting), and syncs your saved Scribe Processes as skills (/scribe:sync).",
-  "version": "2026.09.16.1232",
+  "version": "2026.09.16.2102",
   "author": {
     "name": "Bryan Van Deusen"
   },

plugin/hooks/hooks.json

@@ -53,6 +53,15 @@
             "command": "bash \"${CLAUDE_PLUGIN_ROOT}/hooks/scribe_after_write.sh\""
           }
         ]
+      },
+      {
+        "matcher": "mcp__.*__get_rule",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash \"${CLAUDE_PLUGIN_ROOT}/hooks/scribe_record_opened.sh\""
+          }
+        ]
       }
     ],
     "PreCompact": [

plugin/hooks/scribe_autoinject.sh

@@ -100,6 +100,8 @@ if [ -n "$session_id" ]; then
   # stops holding what it was told. scribe_rules_live carries the reasoning.
   rule_seen=$(scribe_rules_live "$rulefile")
   [ -n "$rule_seen" ] && exclude_q="${exclude_q}&exclude_rule_ids=${rule_seen}"
+  # What the session actually OPENED, as against what it was shown (#4100).
+  exclude_q="${exclude_q}$(scribe_held_query "$rule_state_dir/${safe_sid}.opened.ids")"
 fi
 
 body=$(curl -fsS --max-time 5 \

plugin/hooks/scribe_defs.sh

@@ -289,6 +289,25 @@ scribe_rules_append() {
   awk -v ts="$now" 'NF { print $1 "\t" ts }' >> "$f" 2>/dev/null || true
 }
 
+# The OPENED ledger's contribution to a rule arm's query string (#4100).
+#
+# TWO LEDGERS, BECAUSE THEY RECORD TWO DIFFERENT FACTS. `.rules.ids` holds
+# every id an arm has NAMED; `.opened.ids` holds the ids the session actually
+# read, written by scribe_record_opened.sh from the `get_rule` call itself.
+# Named is not read: the injected line is a teaser, and one skimmed past
+# leaves nothing behind — least of all across a compaction. Sending both lets
+# the server tell a reader who opened a rule from one who was only shown it,
+# instead of telling them both the same untrue thing.
+#
+# Same reader as the naming ledger on purpose, so ageing, the last-entry-wins
+# rule and the bare-id format are defined once and cannot drift apart.
+scribe_held_query() {
+  local ids
+  ids=$(scribe_rules_live "$1")
+  [ -n "$ids" ] && printf '&held_rule_ids=%s' "$ids"
+  return 0
+}
+
 # ---------------------------------------------------------------------------
 # WHICH PROJECT IS THIS DIRECTORY'S? (#4085)
 #

plugin/hooks/scribe_prior_art.sh

@@ -207,6 +207,8 @@ if [ -n "$session_id" ]; then
   # this arm's sibling hook reads the same rule file through the same helper.
   rule_seen=$(scribe_rules_live "$rulefile")
   [ -n "$rule_seen" ] && rule_exclude_q="&exclude_rule_ids=${rule_seen}"
+  # What the session actually OPENED, as against what it was shown (#4100).
+  rule_exclude_q="${rule_exclude_q}$(scribe_held_query "$state_dir/${safe_sid}.opened.ids")"
 fi
 
 # Not `|| exit 0`: an unreachable instance must not discard a local finding

plugin/hooks/scribe_record_opened.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+# Scribe — record that this session OPENED a rule, not merely saw it named (#4100).
+#
+# WHAT THIS CLOSES
+#
+# The rule arms keep a ledger of every id they have NAMED, and the injected
+# line used to tell the reader "You saw it earlier this session". That claim
+# was never checked. The line those arms emit is a TEASER — title, trigger,
+# `get_rule(N)` — so a session can be named a rule twenty times and never read
+# one word of it, and after a compaction the teaser is summarised away leaving
+# nothing at all. The server was asserting something about the reader's
+# context that it had no way to know.
+#
+# This is the observable half. PostToolUse fires for MCP tools (the event's own
+# output schema carries `updatedMCPToolOutput`, which would be meaningless
+# otherwise), so the `get_rule` CALL can be watched directly.
+#
+# WHY THIS IS NOT THE SELF-REPORT MILESTONE 386 REJECTED
+#
+# 386 ruled out asking the session whether it holds a rule, because a model
+# asked "do you still hold rule 156?" will say yes and the answer is
+# unverifiable self-report. That objection is about ASKING. This asks nobody:
+# a tool call happened or it did not, and the harness reports it either way.
+# Recording what a session DID is a different kind of evidence from believing
+# what it says about itself.
+#
+# WHAT IT DELIBERATELY DOES NOT DO
+#
+# It does not prove the rule is still in context — nothing can, and a
+# compaction can drop it moments later. That is why `.opened.ids` ages exactly
+# like `.rules.ids` and is cleared on the same events (#3749): both ledgers
+# describe a context that no longer exists once the context is destroyed. The
+# claim it supports is only ever "you opened this, pull it again if you no
+# longer hold it", which stays true in every case and carries its own remedy.
+#
+# EXIT 0, ALWAYS. This decorates a ledger; a bookkeeping failure must never
+# turn a successful tool call into a hook error. Worst case the id is missed
+# and the reader is offered a rule it already read — the cost of a wrong guess
+# here is one extra line, in the direction that shows more rather than less.
+set -uo pipefail
+
+event=$(cat 2>/dev/null || true)
+[ -n "$event" ] || exit 0
+
+# No jq, no ledger — and no complaint. Every other hook degrades the same way
+# rather than printing a tooling error in front of the operator's work (#4107
+# tracks making that dependency honest; this is not the place to diverge).
+command -v jq >/dev/null 2>&1 || exit 0
+
+session_id=$(printf '%s' "$event" | jq -r '.session_id // empty' 2>/dev/null) || session_id=""
+[ -n "$session_id" ] || exit 0
+
+# The matcher in hooks.json already narrows to the get_rule tools, but the
+# server segment of an MCP tool name varies with how the plugin was installed,
+# so the id is read from whichever field is actually present rather than from
+# an assumed tool name. An event that carries none simply records nothing.
+rule_id=$(printf '%s' "$event" \
+  | jq -r '(.tool_input.rule_id // empty) | tostring' 2>/dev/null) || rule_id=""
+rule_id=$(printf '%s' "$rule_id" | tr -cd '0-9')
+[ -n "$rule_id" ] || exit 0
+
+# The same directory the naming ledger uses. One session keeps its state in one
+# place, and the prior-art name is kept for the reason scribe_tool_rules.sh
+# gives: renaming it would orphan every live session's state for a cosmetic
+# gain.
+state_dir="${TMPDIR:-/tmp}/scribe-priorart"
+mkdir -p "$state_dir" 2>/dev/null || true
+safe_sid=$(printf '%s' "$session_id" | tr -c 'A-Za-z0-9._-' '_')
+
+# shellcheck source=plugin/hooks/scribe_defs.sh
+. "$(dirname "${BASH_SOURCE[0]}")/scribe_defs.sh"
+
+# Stamped and append-only, exactly like the naming ledger — so the same reader
+# (`scribe_rules_live`) ages both, and the last entry for an id wins.
+printf '%s\n' "$rule_id" | scribe_rules_append "$state_dir/${safe_sid}.opened.ids"
+exit 0

plugin/hooks/scribe_session_context.sh

@@ -105,6 +105,13 @@ case "$source" in
       # Best-effort, like every other filesystem touch in these hooks: a ledger
       # that cannot be removed costs a repeated exclusion, never a session.
       rm -f "${TMPDIR:-/tmp}/scribe-priorart/${safe_sid}.rules.ids" 2>/dev/null || true
+      # BOTH ledgers, for one reason (#4100). `.opened.ids` records what the
+      # session read; a compaction is exactly the event that takes it away
+      # again. Clearing the naming ledger while keeping this one would leave
+      # the surfacing arms telling a freshly-summarised session "you opened
+      # it earlier" about a rule that is no longer anywhere in its context —
+      # a more confident version of the claim this milestone removed.
+      rm -f "${TMPDIR:-/tmp}/scribe-priorart/${safe_sid}.opened.ids" 2>/dev/null || true
     fi
     ;;
 esac

plugin/hooks/scribe_tool_rules.sh

@@ -87,6 +87,8 @@ if [ -n "$session_id" ]; then
   # session is still holding. scribe_rules_live carries the reasoning.
   rule_seen=$(scribe_rules_live "$rulefile")
   [ -n "$rule_seen" ] && rule_exclude_q="&exclude_rule_ids=${rule_seen}"
+  # What the session actually OPENED, as against what it was shown (#4100).
+  rule_exclude_q="${rule_exclude_q}$(scribe_held_query "$state_dir/${safe_sid}.opened.ids")"
 fi
 
 # `|| exit 0` here, unlike the prior-art hook: there is no local arm whose

scripts/check_plugin.py

@@ -345,13 +345,43 @@ SMOKE_EVENTS: dict[str, str] = {
         {"session_id": "smoke", "transcript_path": "/nonexistent/smoke.jsonl",
          "cwd": ".", "hook_event_name": "Stop", "stop_hook_active": False}
     ),
+    # The PreCompact preserver (#3680). Its whole contract is the inverse of
+    # every other hook's: it must exit 0 AND print, because stdout is what
+    # becomes the summarizer's custom instructions. A silent success here is
+    # the failure mode, and it would look like every other hook's success.
+    "scribe_precompact_preserve.sh": json.dumps(
+        {"session_id": "smoke", "cwd": ".", "hook_event_name": "PreCompact",
+         "trigger": "manual", "custom_instructions": None}
+    ),
+    # The opened-ledger recorder (#4100). It writes to TMPDIR and prints
+    # nothing — a PostToolUse hook that emitted output would put a line in
+    # front of every get_rule call, which is the opposite of its purpose. The
+    # smoke case is a well-formed open: it must exit 0 and stay silent.
+    "scribe_record_opened.sh": json.dumps(
+        {"session_id": "smoke", "cwd": ".",
+         "tool_name": "mcp__scribe__get_rule", "tool_input": {"rule_id": 1},
+         "tool_response": {}}
+    ),
     # The shared library is sourced, never run; executed bare it defines
     # functions and exits — silent by construction.
     "scribe_defs.sh": "",
 }
 
-# The one hook that legitimately produces output with no credentials.
-STATIC_FLOOR = "scribe_session_context.sh"
+# The hooks that legitimately produce output with NO credentials, each for its
+# own reason — named per hook rather than shared, because "this one is allowed
+# to speak" is exactly the kind of exemption that quietly grows to cover a hook
+# that is merely leaking.
+STATIC_EMITTERS = {
+    # The two-tier SessionStart design: the bundled static tier ships whatever
+    # the instance does, and that floor is the whole point of the split.
+    "scribe_session_context.sh": "static floor present",
+    # PreCompact's contract is INVERTED (#3680). Its stdout becomes the
+    # summarizer's custom instructions, and what must survive a summary is
+    # known without asking anything — so it needs no instance, and silence is
+    # the failure mode rather than the success one. Read as a generic hook it
+    # would look like a leak; it is the opposite.
+    "scribe_precompact_preserve.sh": "preservation instructions present",
+}
 # The hooks that say so when a configured instance does not answer (#2932).
 OUTAGE_SPEAKERS = {"scribe_prior_art.sh", "scribe_after_write.sh"}
 OUTAGE_LINE = "> Scribe did not answer the prior-art check"
@@ -398,14 +428,13 @@ def check_fail_open() -> None:
                      f"a recall aid may never fail the operator's action")
                 continue
             out = proc.stdout.strip()
-            if script.name == STATIC_FLOOR:
-                # Emits its bundled static tier regardless; that floor is the
-                # whole point of the two-tier design.
+            if script.name in STATIC_EMITTERS:
+                what = STATIC_EMITTERS[script.name]
                 if not out:
-                    fail(f"{rel} [{label}]: emitted nothing — the static "
-                         f"behavioural floor must survive having no credentials")
+                    fail(f"{rel} [{label}]: emitted nothing — this hook's "
+                         f"output must survive having no credentials ({what})")
                 else:
-                    ok(f"{rel} [{label}]: exit 0, static floor present")
+                    ok(f"{rel} [{label}]: exit 0, {what}")
             elif out and label == "unreachable" and script.name in OUTAGE_SPEAKERS:
                 # The only thing allowed here is the outage line itself.
                 try:

src/scribe/routes/plugin.py

@@ -100,6 +100,13 @@ async def autoinject_retrieve():
                              purpose: one session keeps ONE rule ledger, so a
                              rule named by any arm is not re-announced by
                              another. Ages out (#3751), so salience decays.
+        held_rule_ids      — comma-separated rule ids the session actually
+            (opt)            OPENED, observed from the `get_rule` call itself
+                             rather than claimed. A rule on exclude_rule_ids
+                             was NAMED; a rule here was READ, and the two say
+                             different things about what the reader holds —
+                             so they get different lines (#4100). Shares the
+                             ledger directory and the same clear-on-compact.
 
     TWO ARMS, TWO SETS OF GATES. Rules ride the same hook and the same query
     but nothing else: the notes menu can be disabled, thresholded and top-k'd
@@ -116,9 +123,10 @@ async def autoinject_retrieve():
     project_id, _repo, _unbound = await _project_scope()
     exclude_ids = _int_list(request.args.get("exclude_ids"))
     exclude_rule_ids = _int_list(request.args.get("exclude_rule_ids"))
+    held_rule_ids = _int_list(request.args.get("held_rule_ids"))
 
     rules = await plugin_ctx_svc.build_prompt_rule_hint(
-        g.user.id, q, project_id=project_id, exclude_rule_ids=exclude_rule_ids
+        g.user.id, q, project_id=project_id, exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids
     )
     result = await plugin_ctx_svc.build_autoinject_hint(
         g.user.id, q, project_id=project_id, exclude_ids=exclude_ids
@@ -157,14 +165,20 @@ async def pre_tool_rules():
                                   ledger on purpose: one session keeps one
                                   list, so a rule named by either arm is not
                                   re-offered by the other.
+        held_rule_ids (opt)     — rule ids the session actually OPENED, as
+                                  against merely named. Named and read are
+                                  different claims about the reader's
+                                  context, so they get different lines
+                                  (#4100).
     """
     tool = (request.args.get("tool") or "tool").strip()
     command = request.args.get("command") or ""
     project_id, _repo, _unbound = await _project_scope()
     exclude_rule_ids = _int_list(request.args.get("exclude_rule_ids"))
+    held_rule_ids = _int_list(request.args.get("held_rule_ids"))
     result = await plugin_ctx_svc.build_tool_rule_hint(
         g.user.id, tool, command,
-        project_id=project_id, exclude_rule_ids=exclude_rule_ids,
+        project_id=project_id, exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids,
     )
     return jsonify(result)
 
@@ -202,6 +216,9 @@ async def write_path_prior_art():
                              above, and for the same reason: a rule named
                              twenty turns ago should not be re-offered on
                              every subsequent write.
+        held_rule_ids (opt)  — RULE ids the session actually OPENED, as
+                             against merely named; drives the third
+                             reference wording (#4100).
         exclude_derive (opt) — comma-separated derive keys (a derive group id
                              or `canon:<snippet_id>`) already named this
                              session by the ledger arm (#2900); its own
@@ -225,6 +242,7 @@ async def write_path_prior_art():
         p.strip() for p in (request.args.get("exclude_derive") or "").split(",") if p.strip()
     ]
     exclude_rule_ids = _int_list(request.args.get("exclude_rule_ids"))
+    held_rule_ids = _int_list(request.args.get("held_rule_ids"))
     shapes = _parse_shapes(request.args.get("shapes") or "")
     api_key = getattr(g, "api_key", None)
     may_stamp = api_key is None or getattr(api_key, "scope", "") == "write"
@@ -235,7 +253,7 @@ async def write_path_prior_art():
         stamp_shapes=shapes if may_stamp else None,
         repo_key=repo_bindings_svc.normalize_repo_key(repo) if repo else "",
         exclude_derive=exclude_derive,
-        exclude_rule_ids=exclude_rule_ids,
+        exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids,
     )
     return jsonify(result)
 

src/scribe/services/plugin_context.py

@@ -927,6 +927,7 @@ async def build_prompt_rule_hint(
     *,
     project_id: int = 0,
     exclude_rule_ids: list[int] | None = None,
+    held_rule_ids: list[int] | None = None,
 ) -> dict:
     """Rules and preferences that may apply to what the operator just asked.
 
@@ -985,6 +986,7 @@ async def build_prompt_rule_hint(
         duration_ms = (time.perf_counter() - t0) * 1000.0
 
         already = set(exclude_rule_ids or [])
+        held = set(held_rule_ids or [])
         fresh = [(score, rule) for score, rule in hits if rule.id not in already]
 
         # BEFORE the early return, for the reason both sibling arms spell out
@@ -1020,7 +1022,10 @@ async def build_prompt_rule_hint(
             return out
 
         lines = [
-            _rule_hint_line(rule, where="to this request", seen=rule.id in already)
+            _rule_hint_line(
+                rule, where="to this request",
+                seen=rule.id in already, held=rule.id in held,
+            )
             for _score, rule in hits
         ]
         # FRESH-ONLY (#3752). A reference is a rendering decision, not a
@@ -1297,7 +1302,9 @@ def _rule_band(hits: list) -> list:
     return [(s, r) for s, r in hits if s >= top - _RULEHINT_BAND]
 
 
-def _rule_hint_line(rule, *, where: str, seen: bool, compact: bool = False) -> str:
+def _rule_hint_line(
+    rule, *, where: str, seen: bool, held: bool = False, compact: bool = False,
+) -> str:
     """One rule hint line — both arms, both tails, both kinds (#3750, #3849).
 
     THREE INDEPENDENT AXES SINCE #3851. `compact` joins `kind` and `seen`, and
@@ -1380,10 +1387,34 @@ def _rule_hint_line(rule, *, where: str, seen: bool, compact: bool = False) -> s
         "for how this has been done before" if preference
         else "before deciding it does not apply"
     )
+    # THREE STATES, BECAUSE TWO OF THEM WERE BEING TOLD THE SAME LIE (#4100).
+    #
+    # `seen` means an arm NAMED this rule earlier. It does not mean the session
+    # read it — the line is a teaser, and a teaser skimmed past leaves nothing
+    # behind, least of all after a compaction summarises the turn it arrived
+    # in. "You saw it earlier this session" asserted something about the
+    # reader's context that the server had no way to know.
+    #
+    # `held` is the observable half: a PostToolUse hook watches for the
+    # `get_rule` call itself, so this is a recorded EVENT rather than a claim.
+    # That distinction is what keeps the non-goal above intact — the objection
+    # was to asking a model about its own context, not to noticing what it did.
+    #
+    # The middle state is the honest one and the one that was missing: named,
+    # not opened. It gets the full invitation, because a session that skipped
+    # the teaser is in almost the same position as one that never saw it.
+    if held:
+        tail = (
+            f"You opened it earlier this session; pull it with "
+            f"get_rule({rule.id}) again if you no longer hold it."
+        )
+    elif seen:
+        tail = (
+            f"Mentioned earlier this session but not opened — read it with "
+            f"get_rule({rule.id}) {reason}."
+        )
+    else:
         tail = (
-        f"You saw it earlier this session; pull it with get_rule({rule.id}) "
-        "if you no longer hold it."
-        if seen else
             f"Read it with get_rule({rule.id}) {reason}; it is not in this "
             "session's loaded set."
         )
@@ -1421,6 +1452,7 @@ async def build_write_path_hint(
     repo_key: str = "",
     exclude_derive: list[str] | None = None,
     exclude_rule_ids: list[int] | None = None,
+    held_rule_ids: list[int] | None = None,
 ) -> dict:
     """Prior-art hint for the plugin's PreToolUse hook on Write/Edit.
 
@@ -1842,6 +1874,7 @@ async def build_write_path_hint(
     rule_ids: list[int] = []
     try:
         already = set(exclude_rule_ids or [])
+        held = set(held_rule_ids or [])
         # Timed like the notes arm above. Without this the rule row was the one
         # source in the whole readout reporting a null p90_duration_ms (#3311)
         # — a gap that reads as "this surface is somehow not measurable" rather
@@ -1867,6 +1900,7 @@ async def build_write_path_hint(
             lines.append(
                 _rule_hint_line(
                     rule, where="here", seen=rule.id in already,
+                    held=rule.id in held,
                     compact=idx > 0,
                 )
             )
@@ -1957,6 +1991,7 @@ async def build_tool_rule_hint(
     *,
     project_id: int = 0,
     exclude_rule_ids: list[int] | None = None,
+    held_rule_ids: list[int] | None = None,
 ) -> dict:
     """Standing rules that may apply to the ACTION about to be taken (#3476).
 
@@ -2011,6 +2046,7 @@ async def build_tool_rule_hint(
         duration_ms = (time.perf_counter() - t0) * 1000.0
 
         already = set(exclude_rule_ids or [])
+        held = set(held_rule_ids or [])
         # Band first, dedup second — see the sibling arm for why that order is
         # load-bearing rather than incidental.
         kept = _rule_band(hits)
@@ -2048,6 +2084,7 @@ async def build_tool_rule_hint(
             _rule_hint_line(
                 rule, where=f"to this {tool_name} call",
                 seen=rule.id in already,
+                held=rule.id in held,
                 # Rank decides volume (#3851): the ranker's best guess gets the
                 # trigger, the rest get cited.
                 compact=idx > 0,

tests/test_rule_opened_ledger.py

@@ -0,0 +1,166 @@
+"""Named is not read: the ledger's third state (#4100).
+
+WHY THIS EXISTS
+
+Milestone 386 made a repeat REFERENCED rather than withheld, and the line it
+chose says "You saw it earlier this session". That claim was never checked.
+The arms emit a TEASER — title, trigger, `get_rule(N)` — so a session can be
+shown a rule twenty times and never read a word of it, and a compaction
+summarises the teaser away leaving nothing at all. The server was asserting
+something about the reader's context it had no way to know.
+
+`.opened.ids` is the observable half, written by a PostToolUse hook from the
+`get_rule` call itself. That is why this is not the self-report 386 rejected:
+the objection was to ASKING a model about its own context, and a tool call is
+an event the harness reports whether anyone asks or not.
+
+WHAT THIS PINS
+
+The three states and their three lines, the hook that records an open, and the
+fact that BOTH ledgers die together on a compaction — a session told "you
+opened it earlier" about a rule that was just summarised out of its context
+would be a more confident version of the bug this removes.
+"""
+from __future__ import annotations
+
+import json
+import os
+import re
+import shutil
+import subprocess
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+
+from scribe.services.plugin_context import _rule_hint_line
+
+ROOT = Path(__file__).resolve().parents[1]
+HOOKS = ROOT / "plugin" / "hooks"
+RECORDER = HOOKS / "scribe_record_opened.sh"
+
+
+def _rule(rid=156, kind="rule"):
+    return MagicMock(id=rid, kind=kind, title="A wait with no deadline is a bug",
+                     when_to_apply="crossing a process boundary")
+
+
+# ── the three lines ────────────────────────────────────────────────────────
+
+def test_a_rule_never_surfaced_is_offered_as_new():
+    line = _rule_hint_line(_rule(), where="here", seen=False, held=False)
+    assert "not in this session's loaded set" in line
+
+
+def test_a_rule_named_but_not_opened_says_so_and_still_invites():
+    """The state that did not exist. It must NOT claim the reader saw it, and
+    must still carry the pull pointer — a session that skipped the teaser is
+    in nearly the position of one that was never shown it."""
+    line = _rule_hint_line(_rule(), where="here", seen=True, held=False)
+    assert "not opened" in line
+    assert "get_rule(156)" in line
+    assert "You saw it earlier" not in line, (
+        "the middle state is claiming the reader read something they did not"
+    )
+
+
+def test_a_rule_the_session_opened_is_described_as_opened():
+    line = _rule_hint_line(_rule(), where="here", seen=True, held=True)
+    assert "opened it earlier" in line
+    assert "get_rule(156)" in line
+
+
+def test_the_three_states_produce_three_different_lines():
+    """Guard against a refactor collapsing two branches: each state has to be
+    distinguishable, or the distinction this milestone bought is gone while
+    every individual assertion above still passes."""
+    lines = {
+        _rule_hint_line(_rule(), where="here", seen=s, held=h)
+        for s, h in ((False, False), (True, False), (True, True))
+    }
+    assert len(lines) == 3
+
+
+def test_held_outranks_seen_regardless_of_kind():
+    """`kind` moves the head and the ledger moves the tail; #3497's history is
+    the two being reasoned about together and one of them being forgotten."""
+    for kind in ("rule", "preference"):
+        line = _rule_hint_line(_rule(kind=kind), where="here", seen=True, held=True)
+        assert "opened it earlier" in line
+
+
+# ── the recorder ───────────────────────────────────────────────────────────
+
+def _run_recorder(event: dict, tmp: Path) -> Path:
+    for tool in ("bash", "jq"):
+        if shutil.which(tool) is None:
+            pytest.skip(f"hook runtime tool {tool!r} not installed")
+    env = {"PATH": os.environ["PATH"], "HOME": str(tmp), "TMPDIR": str(tmp)}
+    out = subprocess.run(["bash", str(RECORDER)], input=json.dumps(event),
+                         capture_output=True, text=True, env=env, timeout=30)
+    assert out.returncode == 0, out.stderr
+    return tmp / "scribe-priorart" / "s1.opened.ids"
+
+
+def test_opening_a_rule_is_recorded(tmp_path):
+    led = _run_recorder(
+        {"session_id": "s1", "tool_name": "mcp__scribe__get_rule",
+         "tool_input": {"rule_id": 156}}, tmp_path)
+    assert led.exists()
+    assert led.read_text().split("\t")[0] == "156"
+
+
+def test_the_entry_is_stamped_so_it_ages_like_the_naming_ledger(tmp_path):
+    """Both ledgers are read by `scribe_rules_live`, which ages on that stamp.
+    An unstamped entry never expires — bounded, but it would mean an opened
+    rule stays 'opened' for a session's whole life."""
+    led = _run_recorder(
+        {"session_id": "s1", "tool_name": "mcp__scribe__get_rule",
+         "tool_input": {"rule_id": 9}}, tmp_path)
+    parts = led.read_text().strip().split("\t")
+    assert len(parts) == 2 and parts[1].isdigit()
+
+
+@pytest.mark.parametrize("event", [
+    {"session_id": "s1", "tool_name": "mcp__scribe__get_rule", "tool_input": {}},
+    {"session_id": "s1", "tool_name": "mcp__scribe__get_rule",
+     "tool_input": {"rule_id": "../../etc"}},
+    {"tool_name": "mcp__scribe__get_rule", "tool_input": {"rule_id": 5}},
+])
+def test_an_event_with_nothing_usable_records_nothing_and_still_exits_zero(event, tmp_path):
+    """A hook that fails a tool call over bookkeeping is worse than one that
+    misses an id: the cost of a miss is one extra line, in the direction that
+    shows more rather than less."""
+    led = _run_recorder(event, tmp_path)
+    assert not led.exists()
+
+
+# ── the two ledgers stay in step ───────────────────────────────────────────
+
+def test_a_compaction_clears_both_ledgers():
+    """The one that would be worst to get wrong. `.opened.ids` describes a
+    context the compaction just destroyed, so keeping it while clearing the
+    naming ledger would have the arms telling a freshly-summarised session
+    "you opened it earlier" about a rule now nowhere in its context.
+    """
+    sh = (HOOKS / "scribe_session_context.sh").read_text()
+    block = sh.split("case \"$source\" in")[1].split("esac")[0]
+    assert "compact|clear)" in block
+    for led in (".rules.ids", ".opened.ids"):
+        assert re.search(rf"rm -f .*{re.escape(led)}", block), (
+            f"{led} survives a compaction that destroyed what it describes"
+        )
+
+
+def test_the_recorder_is_registered_on_the_get_rule_tool():
+    hooks = json.loads((HOOKS / "hooks.json").read_text())["hooks"]
+    posts = hooks["PostToolUse"]
+    mine = [b for b in posts
+            if any("scribe_record_opened.sh" in h["command"] for h in b["hooks"])]
+    assert len(mine) == 1, "the opened-recorder is not registered exactly once"
+    # An MCP tool's server segment varies with how the plugin was installed, so
+    # the matcher must not pin one spelling of it.
+    matcher = mine[0]["matcher"]
+    assert re.fullmatch(matcher, "mcp__plugin_scribe_scribe__get_rule"), matcher
+    assert re.fullmatch(matcher, "mcp__scribe__get_rule"), matcher
+    assert not re.fullmatch(matcher, "Bash"), matcher

tests/test_rule_usage_wiring.py

@@ -747,7 +747,13 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
     # repo and `project_id=` where a `.scribe` marker names the project. Both
     # halves are one contract with the route, so both are pinned.
     assert "scribe_scope_query" in hook, "hook no longer asks for a project scope"
-    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {"repo", "project_id"}
+    # `held_rule_ids` joins them for the same reason (#4100): the OPENED ledger
+    # is read by a shared helper so its ageing and format cannot drift from the
+    # naming ledger's, which means the key is spelled in defs rather than here.
+    assert "scribe_held_query" in hook, "hook no longer sends the opened ledger"
+    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {
+        "repo", "project_id", "held_rule_ids",
+    }
 
     # Both scope keys are read by the shared _project_scope() helper, not inline.
     assert "_project_scope()" in handler
@@ -756,6 +762,11 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
         assert f'request.args.get("{arg}"' in scope, (
             f"the hooks can send {arg!r} and the route never reads it"
         )
+    # Read by the handler itself, not the scope helper — it is about what the
+    # reader holds, not about which project the work belongs to.
+    assert 'request.args.get("held_rule_ids")' in handler, (
+        "the hook sends held_rule_ids and the route never reads it"
+    )
     for arg in ("tool", "command", "exclude_rule_ids"):
         assert f'request.args.get("{arg}")' in handler, (
             f"the hook sends {arg!r} and the route never reads it"

tests/test_write_path_trigger.py

@@ -938,8 +938,13 @@ def test_route_reads_every_arg_the_hook_sends():
     # whichever of `repo=` / `project_id=` scribe_scope_query picks, so the hook
     # splices in its output and the helper is the other half of the contract.
     assert "scribe_scope_query" in hook, "hook no longer asks for a project scope"
+    # Same arrangement for the OPENED ledger (#4100): spelled once in the
+    # helper so its ageing and format cannot drift from the naming ledger's.
+    assert "scribe_held_query" in hook, "hook no longer sends the opened ledger"
     defs = (HOOK.parent / "scribe_defs.sh").read_text()
-    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {"repo", "project_id"}
+    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {
+        "repo", "project_id", "held_rule_ids",
+    }
 
 
 def test_route_resolves_repo_to_a_project_not_to_a_location_filter():