diff --git a/alembic/versions/0113_system_path_patterns.py b/alembic/versions/0113_system_path_patterns.py
new file mode 100644
index 0000000..e63e3c9
--- /dev/null
+++ b/alembic/versions/0113_system_path_patterns.py
@@ -0,0 +1,34 @@
+"""system_path_patterns — a System names the files that are its area
+(milestone 444 step 3, #4756)
+
+Revision ID: 0113
+Revises: 0112
+Create Date: 2026-10-02
+
+A JSONB list of globs relative to the repo root. NOT NULL with a `[]`
+default, so an existing System reads as "no paths yet" rather than as NULL. No
+backfill: which files are which area is a judgment, and the charters that name
+directories in prose are not a mapping anyone confirmed.
+"""
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+revision = "0113"
+down_revision = "0112"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "systems",
+        sa.Column(
+            "path_patterns", postgresql.JSONB(), nullable=False,
+            server_default=sa.text("'[]'::jsonb"),
+        ),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("systems", "path_patterns")
diff --git a/alembic/versions/0114_system_usage_events.py b/alembic/versions/0114_system_usage_events.py
new file mode 100644
index 0000000..86734a8
--- /dev/null
+++ b/alembic/versions/0114_system_usage_events.py
@@ -0,0 +1,45 @@
+"""system_usage_events — were an area's rulings read once its files were
+touched? (milestone 444 step 4, #4757)
+
+Revision ID: 0114
+Revises: 0113
+Create Date: 2026-10-03
+
+The usage twin for Systems, beside note_usage_events and rule_usage_events and
+separate from both for the same reason they are separate from each other: a
+System id restores through its own map. FK-free like its siblings; no CHECK on
+`event`, like its siblings.
+"""
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0114"
+down_revision = "0113"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "system_usage_events",
+        sa.Column("id", sa.BigInteger(), primary_key=True),
+        sa.Column(
+            "created_at", sa.DateTime(timezone=True), nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.Column("user_id", sa.BigInteger(), nullable=True),
+        sa.Column("system_id", sa.BigInteger(), nullable=False),
+        sa.Column("event", sa.Text(), nullable=False),
+        sa.Column("source", sa.Text(), nullable=False),
+        sa.Column("project_id", sa.BigInteger(), nullable=True),
+    )
+    op.create_index(
+        "ix_system_usage_system_event", "system_usage_events", ["system_id", "event"]
+    )
+    op.create_index("ix_system_usage_created_at", "system_usage_events", ["created_at"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_system_usage_created_at", table_name="system_usage_events")
+    op.drop_index("ix_system_usage_system_event", table_name="system_usage_events")
+    op.drop_table("system_usage_events")
diff --git a/frontend/src/api/systems.ts b/frontend/src/api/systems.ts
index 24d3637..7d19ed1 100644
--- a/frontend/src/api/systems.ts
+++ b/frontend/src/api/systems.ts
@@ -14,6 +14,12 @@ export interface System {
   color: string | null;
   status: "active" | "archived";
   order_index: number;
+  /**
+   * The files that are this area, as globs relative to the repo root: `*`
+   * within one directory, `**` across any depth, a plain directory covering
+   * everything under it. Empty means the area has not named its files.
+   */
+  path_patterns: string[];
   open_issue_count: number;
   created_at: string | null;
   updated_at: string | null;
@@ -39,7 +45,13 @@ export interface CreatedSystem extends System {
 
 export async function createSystem(
   projectId: number,
-  data: { name: string; description?: string; color?: string; canonical_id?: number },
+  data: {
+    name: string;
+    description?: string;
+    color?: string;
+    canonical_id?: number;
+    path_patterns?: string[];
+  },
 ): Promise<CreatedSystem> {
   return apiPost(`/api/projects/${projectId}/systems`, data);
 }
@@ -53,6 +65,7 @@ export async function updateSystem(
     color: string | null;
     status: "active" | "archived";
     order_index: number;
+    path_patterns: string[];
   }>,
 ): Promise<System> {
   return apiPatch(`/api/projects/${projectId}/systems/${systemId}`, data);
diff --git a/frontend/src/components/SystemsSection.vue b/frontend/src/components/SystemsSection.vue
index d3411f7..f69fffd 100644
--- a/frontend/src/components/SystemsSection.vue
+++ b/frontend/src/components/SystemsSection.vue
@@ -28,6 +28,7 @@ const newDescription = ref("");
 // feature two matchers to keep in step, which is the exact drift the catalog
 // exists to end. The server still applies an exact hit on submit.
 const newCanonicalId = ref<number | null>(null);
+const newPaths = ref("");
 const creating = ref(false);
 // An `overlap` the server offered after a create — an offer, never applied.
 const suggestion = ref<{ systemId: number; match: CanonicalMatch } | null>(null);
@@ -37,6 +38,7 @@ const editingId = ref<number | null>(null);
 const editName = ref("");
 const editDescription = ref("");
 const editCanonicalId = ref<number | null>(null);
+const editPaths = ref("");
 const savingEdit = ref(false);
 
 // Mapping review
@@ -55,6 +57,16 @@ const visibleSystems = computed(() =>
 
 const proposals = computed(() => canon.proposalsByProject[props.projectId] ?? []);
 
+// The files field is one pattern per line. The server is the one that
+// validates and tidies them, so this only splits — a second validator here
+// would be a second answer to "is this pattern acceptable".
+function parsePaths(text: string): string[] {
+  return text
+    .split("\n")
+    .map((line) => line.trim())
+    .filter(Boolean);
+}
+
 function areaName(system: System): string | null {
   return canon.byId(system.canonical_id)?.name ?? null;
 }
@@ -89,6 +101,7 @@ function openCreate() {
   newName.value = "";
   newDescription.value = "";
   newCanonicalId.value = null;
+  newPaths.value = "";
 }
 
 function cancelCreate() {
@@ -96,6 +109,7 @@ function cancelCreate() {
   newName.value = "";
   newDescription.value = "";
   newCanonicalId.value = null;
+  newPaths.value = "";
 }
 
 async function submitCreate() {
@@ -107,6 +121,7 @@ async function submitCreate() {
       name,
       description: newDescription.value.trim() || undefined,
       canonical_id: newCanonicalId.value ?? undefined,
+      path_patterns: parsePaths(newPaths.value),
     });
     cancelCreate();
     if (created.canonical_suggestion) {
@@ -157,6 +172,7 @@ function startEdit(system: System) {
   editName.value = system.name;
   editDescription.value = system.description;
   editCanonicalId.value = system.canonical_id;
+  editPaths.value = system.path_patterns.join("\n");
 }
 
 function cancelEdit() {
@@ -171,6 +187,7 @@ async function submitEdit(system: System) {
     await store.updateSystem(props.projectId, system.id, {
       name,
       description: editDescription.value.trim(),
+      path_patterns: parsePaths(editPaths.value),
     });
     // The mapping is a separate write with its own validation — one column,
     // one writer (services/canonical_systems.set_system_canonical).
@@ -180,8 +197,9 @@ async function submitEdit(system: System) {
     }
     editingId.value = null;
     toast.show("System updated");
-  } catch {
-    toast.show("Failed to update system", "error");
+  } catch (e) {
+    // A refused pattern comes back as a 400 naming it — say which.
+    toast.show(apiErrorMessage(e, "Failed to update system"), "error");
   } finally {
     savingEdit.value = false;
   }
@@ -337,6 +355,20 @@ async function confirmDelete() {
           Files this system under an area shared by every project. Your name stays as you typed it.
         </span>
       </label>
+      <label class="area-field">
+        <span class="area-label">Files</span>
+        <textarea
+          v-model="newPaths"
+          class="fs-input system-textarea system-paths-input"
+          rows="2"
+          placeholder="e.g. src/billing — one pattern per line"
+          aria-label="System files"
+          spellcheck="false"
+        ></textarea>
+        <span class="field-hint">
+          One pattern per line, from the repo root. <code>*</code> stays in one folder, <code>**</code> reaches any depth, and a folder covers everything in it.
+        </span>
+      </label>
       <div class="system-form-actions">
         <button type="submit" class="btn-primary btn-compact" :disabled="!newName.trim() || creating">
           {{ creating ? "Creating…" : "Create" }}
@@ -397,6 +429,17 @@ async function confirmDelete() {
                 </option>
               </select>
             </label>
+            <label class="area-field">
+              <span class="area-label">Files</span>
+              <textarea
+                v-model="editPaths"
+                class="fs-input system-textarea system-paths-input"
+                rows="2"
+                placeholder="One pattern per line, from the repo root"
+                aria-label="System files"
+                spellcheck="false"
+              ></textarea>
+            </label>
             <div class="system-form-actions">
               <button type="submit" class="btn-primary btn-compact" :disabled="!editName.trim() || savingEdit">
                 {{ savingEdit ? "Saving…" : "Save" }}
@@ -430,6 +473,9 @@ async function confirmDelete() {
               >{{ areaName(system) }}</span>
             </div>
             <p v-if="system.description" class="system-description">{{ system.description }}</p>
+            <ul v-if="system.path_patterns.length" class="system-paths" aria-label="Files">
+              <li v-for="pattern in system.path_patterns" :key="pattern" class="system-path">{{ pattern }}</li>
+            </ul>
           </div>
           <div class="system-actions">
             <button class="action-btn" title="Edit" aria-label="Edit system" @click="startEdit(system)">
@@ -627,6 +673,28 @@ async function confirmDelete() {
 .system-textarea { resize: vertical; }
 
 .system-form-actions { display: flex; gap: 0.4rem; }
+.system-paths-input { font-family: var(--fs-font-mono); font-size: 0.8rem; }
+
+/* The area's files (milestone 444). Mono because they are paths to be read
+   character for character; small because they qualify the card, not lead it. */
+.system-paths {
+  list-style: none;
+  margin: var(--fs-space-2) 0 0;
+  padding: 0;
+  display: flex;
+  flex-wrap: wrap;
+  gap: var(--fs-space-1);
+}
+.system-path {
+  font-family: var(--fs-font-mono);
+  font-size: 0.7rem;
+  color: var(--fs-text-secondary);
+  background: var(--fs-surface-page);
+  border: 1px solid var(--fs-border-color);
+  border-radius: var(--fs-radius-sm);
+  padding: 0.05rem 0.4rem;
+  word-break: break-all;
+}
 
 /* RESTORED (#2444). Both lost their base rule to a CSS sweep; only the
    `--archived` modifier and the `:hover .system-actions` reveal survived.
diff --git a/frontend/src/stores/systems.ts b/frontend/src/stores/systems.ts
index ed6a485..6e2c318 100644
--- a/frontend/src/stores/systems.ts
+++ b/frontend/src/stores/systems.ts
@@ -22,7 +22,7 @@ export const useSystemsStore = defineStore("systems", () => {
 
   async function createSystem(
     projectId: number,
-    data: { name: string; description?: string; color?: string; canonical_id?: number },
+    data: Parameters<typeof api.createSystem>[1],
   ) {
     const system = await api.createSystem(projectId, data);
     if (!systemsByProject.value[projectId]) systemsByProject.value[projectId] = [];
@@ -33,7 +33,7 @@ export const useSystemsStore = defineStore("systems", () => {
   async function updateSystem(
     projectId: number,
     systemId: number,
-    data: Partial<Pick<System, "name" | "description" | "color" | "status" | "order_index">>,
+    data: Parameters<typeof api.updateSystem>[2],
   ) {
     const system = await api.updateSystem(projectId, systemId, data);
     const list = systemsByProject.value[projectId];
diff --git a/plugin/.claude-plugin/plugin.json b/plugin/.claude-plugin/plugin.json
index 9117cca..7c38fe8 100644
--- a/plugin/.claude-plugin/plugin.json
+++ b/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": "2026.10.02.2259",
+  "version": "2026.10.03.0308",
   "author": {
     "name": "Bryan Van Deusen"
   },
diff --git a/plugin/hooks/scribe_defs.sh b/plugin/hooks/scribe_defs.sh
index 6652be9..8a4c2de 100644
--- a/plugin/hooks/scribe_defs.sh
+++ b/plugin/hooks/scribe_defs.sh
@@ -1123,6 +1123,20 @@ scribe_held_query() {
   return 0
 }
 
+# The Systems whose rulings this session was already shown in full (milestone
+# 444), as the `seen_ruling_systems` query both PreToolUse hooks send. A flat
+# read, not aged like the rule file: a ruling binds for the whole session, and
+# the server already answers a repeat with one short reference line. The file
+# follows the ledger name convention, so a compaction clears it and the
+# rulings are shown in full again to the context that lost them.
+scribe_rulings_query() {
+  local ids
+  [ -f "$1" ] || return 0
+  ids=$(grep -E '^[0-9]+$' "$1" 2>/dev/null | sort -un | tr '\n' ',' | sed 's/,$//')
+  [ -n "$ids" ] && printf '&seen_ruling_systems=%s' "$ids"
+  return 0
+}
+
 # Drop EVERY per-session ledger, matched by convention rather than listed (#4101).
 #
 # A LIST IS THE BUG. Until now the compact/clear branch named its files one at
diff --git a/plugin/hooks/scribe_prior_art.sh b/plugin/hooks/scribe_prior_art.sh
index 5a741b9..80516c0 100755
--- a/plugin/hooks/scribe_prior_art.sh
+++ b/plugin/hooks/scribe_prior_art.sh
@@ -192,6 +192,10 @@ mkdir -p "$state_dir" 2>/dev/null || true
 # A FOURTH channel (milestone 307): standing RULES the write resembles. Its own
 # file for the same reason as the others — a rule named once should not be
 # re-offered on every subsequent write in the session.
+#
+# A FIFTH (milestone 444): the Systems whose RULINGS were shown in full. SHARED
+# with scribe_tool_rules.sh, like the rule file: an area's rulings shown before
+# a command must not be repeated in full before the next edit there.
 idfile=""
 syncfile=""
 derivefile=""
@@ -200,6 +204,8 @@ exclude_q=""
 sync_exclude_q=""
 derive_exclude_q=""
 rule_exclude_q=""
+rulingsfile=""
+rulings_q=""
 if [ -n "$session_id" ]; then
   safe_sid=$(printf '%s' "$session_id" | tr -c 'A-Za-z0-9._-' '_')
   # What this write defined, for the end-of-turn question (milestone 439). A
@@ -214,6 +220,8 @@ if [ -n "$session_id" ]; then
   syncfile="$state_dir/${safe_sid}.sync.ids"
   derivefile="$state_dir/${safe_sid}.derive.ids"
   rulefile="$state_dir/${safe_sid}.rules.ids"
+  rulingsfile="$state_dir/${safe_sid}.rulings.ids"
+  rulings_q=$(scribe_rulings_query "$rulingsfile")
   if [ -f "$idfile" ]; then
     seen=$(tr '\n' ',' < "$idfile" 2>/dev/null | sed 's/,$//')
     [ -n "$seen" ] && exclude_q="&exclude_ids=${seen}"
@@ -242,7 +250,7 @@ fi
 reached=1
 body=$(curl -fsS --max-time 5 \
   -H "Authorization: Bearer ${token}" \
-  "${url%/}/api/plugin/prior-art?path=${path_enc}&code=${code_enc}${repo_q}${exclude_q}${sync_exclude_q}${derive_exclude_q}${rule_exclude_q}${shapes_q}" 2>/dev/null) || { body=""; reached=0; }
+  "${url%/}/api/plugin/prior-art?path=${path_enc}&code=${code_enc}${repo_q}${exclude_q}${sync_exclude_q}${derive_exclude_q}${rule_exclude_q}${rulings_q}${shapes_q}" 2>/dev/null) || { body=""; reached=0; }
 unreached_context=""
 if [ "$reached" = 1 ]; then
   scribe_reached "$state_dir" "${safe_sid:-nosession}"
@@ -271,6 +279,9 @@ if [ -n "$body" ]; then
     if [ -n "$derivefile" ]; then
       scribe_json_list "$body_flat" '.derive_keys' >> "$derivefile" || true
     fi
+    if [ -n "$rulingsfile" ]; then
+      scribe_json_list "$body_flat" '.ruling_system_ids' >> "$rulingsfile" || true
+    fi
   fi
 fi
 
diff --git a/plugin/hooks/scribe_tool_rules.sh b/plugin/hooks/scribe_tool_rules.sh
index 0556393..22cd82f 100644
--- a/plugin/hooks/scribe_tool_rules.sh
+++ b/plugin/hooks/scribe_tool_rules.sh
@@ -68,6 +68,15 @@ lookup_dir=${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}
 scope=$(scribe_scope_query "$lookup_dir")
 [ -n "$scope" ] && repo_q="&${scope}"
 
+# Where the command runs, against the repo's root (milestone 444): the paths a
+# command names are relative to its cwd or absolute, and a System's patterns
+# are relative to the root. The server does the arithmetic; this sends both.
+where_q=""
+repo_root=$(git -C "$lookup_dir" rev-parse --show-toplevel 2>/dev/null || true)
+if [ -n "$repo_root" ]; then
+  where_q="&root=$(printf '%s' "$repo_root" | scribe_urlenc)&cwd=$(printf '%s' "$lookup_dir" | scribe_urlenc)"
+fi
+
 # THE SHARED SESSION LEDGER, and the thing most worth getting right here.
 #
 # scribe_prior_art.sh keeps the rules it has already named in
@@ -82,6 +91,8 @@ state_dir="${TMPDIR:-/tmp}/scribe-priorart"
 mkdir -p "$state_dir" 2>/dev/null || true
 rulefile=""
 rule_exclude_q=""
+rulingsfile=""
+rulings_q=""
 if [ -n "$session_id" ]; then
   safe_sid=$(printf '%s' "$session_id" | tr -c 'A-Za-z0-9._-' '_')
   rulefile="$state_dir/${safe_sid}.rules.ids"
@@ -91,6 +102,10 @@ if [ -n "$session_id" ]; then
   [ -n "$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/${safe_sid}.opened.ids")"
+  # The Systems whose rulings were shown in full — shared with the write-path
+  # hook, for the reason the rule file is.
+  rulingsfile="$state_dir/${safe_sid}.rulings.ids"
+  rulings_q=$(scribe_rulings_query "$rulingsfile")
 fi
 
 # `|| exit 0` here, unlike the prior-art hook: there is no local arm whose
@@ -98,7 +113,7 @@ fi
 # than silence. See the header.
 body=$(curl -fsS --max-time 5 \
   -H "Authorization: Bearer ${token}" \
-  "${url%/}/api/plugin/tool-rules?tool=${tool_enc}&command=${cmd_enc}${repo_q}${rule_exclude_q}" 2>/dev/null) || exit 0
+  "${url%/}/api/plugin/tool-rules?tool=${tool_enc}&command=${cmd_enc}${repo_q}${where_q}${rule_exclude_q}${rulings_q}" 2>/dev/null) || exit 0
 
 body_flat=$(printf '%s' "$body" | scribe_json_flat)
 context=$(scribe_json_pick "$body_flat" '.context')
@@ -111,6 +126,9 @@ context=$(scribe_json_pick "$body_flat" '.context')
 if [ -n "$rulefile" ]; then
   scribe_json_list "$body_flat" '.rule_ids' | scribe_rules_append "$rulefile"
 fi
+if [ -n "$rulingsfile" ]; then
+  scribe_json_list "$body_flat" '.ruling_system_ids' >> "$rulingsfile" || true
+fi
 
 # ── The pre-act checkpoint (#4214, milestone 419) ────────────────────────
 #
diff --git a/plugin/skills/using-scribe/SKILL.md b/plugin/skills/using-scribe/SKILL.md
index 9f3528e..fc6e19d 100644
--- a/plugin/skills/using-scribe/SKILL.md
+++ b/plugin/skills/using-scribe/SKILL.md
@@ -198,6 +198,11 @@ Two constraints on *how* that's achieved:
    work-logs alike. Treat it as the tagging question asked at the moment of
    work: tag the record, create the missing System, or deliberately leave it.
 
+   A System also names its files: `path_patterns`, globs from the repo root.
+   When the work you are tagging touched files its System's patterns don't
+   cover, and they plainly belong to that area, add them with `update_system`
+   — which files are which area is your call, as naming the area was.
+
 8. **Name the record, never just its number.** Whenever you refer to a Scribe
    record — in a message to the operator, a commit message, a task body, a
    work-log — write the id *and* its title: `#3244 "the staleness signal"`,
diff --git a/plugin/skills/using-scribe/writing-records.md b/plugin/skills/using-scribe/writing-records.md
index df8f6d7..1de8793 100644
--- a/plugin/skills/using-scribe/writing-records.md
+++ b/plugin/skills/using-scribe/writing-records.md
@@ -96,6 +96,8 @@ one line each — the statement, who decided, when, and the record it came from:
 
 The description arrives with every record filed under that System, so a ruling
 there reaches each session working in the area without having to win a search.
+Once the System names its files (`path_patterns`), its rulings also arrive with
+the first command or edit in a session that touches them.
 A quote inside a work log does not: it surfaces only when a query happens to
 match it, and the passage that matches is usually the prose around it — often a
 session's *reading* of the ruling rather than the ruling.
diff --git a/src/scribe/mcp/tools/systems.py b/src/scribe/mcp/tools/systems.py
index 1886927..8b2dab7 100644
--- a/src/scribe/mcp/tools/systems.py
+++ b/src/scribe/mcp/tools/systems.py
@@ -9,6 +9,7 @@ tools are thin wrappers.
 Sentinels (match the milestone/task tool conventions):
   - name="" / description="" / color="" / status="" → "leave unchanged" on update
   - order_index=-1 → "leave unchanged" on update (0 is a valid order_index)
+  - path_patterns=None → "leave unchanged" on update ([] clears them)
 """
 from __future__ import annotations
 
@@ -17,6 +18,7 @@ from scribe.services import canonical_systems as canonical_systems_svc
 from scribe.services import milestones as milestones_svc
 from scribe.services import notes as notes_svc
 from scribe.services import systems as systems_svc
+from scribe.services.system_usage import record_system_pulled
 
 # Below this, a project is young enough that the mild "which area is this
 # about?" question stays proportionate; at or above it, a zero-Systems project
@@ -167,6 +169,7 @@ async def create_system(
     name: str,
     description: str = "",
     color: str = "",
+    path_patterns: list[str] | None = None,
 ) -> dict:
     """Create a System (a reusable, self-describing subsystem/area) in a project.
 
@@ -195,11 +198,20 @@ async def create_system(
     under the System, so a ruling there reaches each session working in the
     area; a quote in a work log reaches one only if a search matches it.
 
+    `path_patterns` name the files that ARE the area: globs relative to the
+    repo root, `*` within one directory, `**` across any depth, and a plain
+    directory covering everything under it (`src/billing`,
+    `frontend/src/components/Billing*.vue`). The description says what the
+    area is for; the patterns say where it lives, so work touching those files
+    can be traced to the System without a search. Give them when the area's
+    files are known; a System without them still works for tagging.
+
     Args:
         project_id: The project this system belongs to (required).
         name: Short label (required).
         description: What the system is and how it's used — a name is rarely enough.
         color: Optional UI accent (hex), or empty.
+        path_patterns: The area's files as repo-relative globs, or omit.
 
     Duplicate-gated like the other creates: if a System with the same
     normalized name already exists in this project (archived included), the
@@ -237,7 +249,7 @@ async def create_system(
     system = await systems_svc.create_system(
         uid, project_id=project_id, name=name,
         description=description or None, color=color or None,
-        canonical_id=applied,
+        canonical_id=applied, path_patterns=path_patterns,
     )
     if system is None:
         raise ValueError(f"cannot create system in project {project_id} (no write access)")
@@ -282,6 +294,9 @@ async def get_system(system_id: int) -> dict:
     system = await systems_svc.get_system(uid, system_id)
     if system is None:
         raise ValueError(f"system {system_id} not found")
+    # The pull half of the rulings arm's measurement (milestone 444): a
+    # System whose rulings were shown, then opened.
+    record_system_pulled(user_id=uid, system_id=system_id, source="mcp_get_system")
     records = await systems_svc.list_records_for_system(uid, system_id)
     titles = await milestones_svc.titles_for({r.milestone_id for r in records})
     issues, tasks, notes = [], [], []
@@ -307,6 +322,7 @@ async def update_system(
     color: str = "",
     status: str = "",
     order_index: int = -1,
+    path_patterns: list[str] | None = None,
 ) -> dict:
     """Update a System. Only explicitly provided fields change.
 
@@ -319,10 +335,14 @@ async def update_system(
     history. If the charter above it contradicts a ruling, fix that sentence
     in the same edit.
 
+    `path_patterns` also REPLACES the whole list, and `[]` clears it.
+
     Args:
         status: 'active' or 'archived'. Archive a system to retire it without
             losing history; archived systems hide from default lists.
         order_index: display position (0-based); -1 = leave unchanged.
+        path_patterns: The area's files as repo-relative globs (see
+            create_system). Omit to leave unchanged; [] clears them.
     """
     uid = current_user_id()
     fields: dict = {}
@@ -336,6 +356,8 @@ async def update_system(
         fields["status"] = status
     if order_index >= 0:
         fields["order_index"] = order_index
+    if path_patterns is not None:
+        fields["path_patterns"] = path_patterns
     system = await systems_svc.update_system(uid, system_id, **fields)
     if system is None:
         raise ValueError(f"system {system_id} not found or no write access")
diff --git a/src/scribe/models/__init__.py b/src/scribe/models/__init__.py
index 178fb84..ce9d784 100644
--- a/src/scribe/models/__init__.py
+++ b/src/scribe/models/__init__.py
@@ -60,6 +60,7 @@ from scribe.models.retrieval_log import RetrievalLog  # noqa: E402, F401
 from scribe.models.retrieval_tuning import RetrievalTuningEvent  # noqa: E402, F401
 from scribe.models.note_usage import NoteUsageEvent  # noqa: E402, F401
 from scribe.models.rule_usage import RuleUsageEvent  # noqa: E402, F401
+from scribe.models.system_usage import SystemUsageEvent  # noqa: E402, F401
 from scribe.models.project import Project  # noqa: E402, F401
 from scribe.models.milestone import Milestone  # noqa: E402, F401
 from scribe.models.task_log import TaskLog  # noqa: E402, F401
diff --git a/src/scribe/models/system.py b/src/scribe/models/system.py
index ddd25a7..6788c34 100644
--- a/src/scribe/models/system.py
+++ b/src/scribe/models/system.py
@@ -1,4 +1,5 @@
-from sqlalchemy import ForeignKey, Index, Integer, Text, UniqueConstraint
+from sqlalchemy import ForeignKey, Index, Integer, Text, UniqueConstraint, text
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
@@ -38,6 +39,15 @@ class System(Base, TimestampMixin, SoftDeleteMixin):
     # active | archived — systems accumulate; archive rather than delete.
     status: Mapped[str] = mapped_column(Text, default="active", server_default="active")
     order_index: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
+    # The files that ARE this area, as globs relative to the repo root
+    # (milestone 444). The description says what the area is FOR; these say
+    # where it lives, so a command or edit touching those files can be
+    # resolved to the System — and its rulings — without a similarity search.
+    # NOT NULL with a `[]` default for the reason DesignToken.supersedes gives:
+    # a nullable list has two empties, and every reader must handle both.
+    path_patterns: Mapped[list] = mapped_column(
+        JSONB, nullable=False, default=list, server_default=text("'[]'::jsonb")
+    )
 
     __table_args__ = (
         Index("ix_systems_project_id", "project_id"),
@@ -54,6 +64,7 @@ class System(Base, TimestampMixin, SoftDeleteMixin):
             "color": self.color,
             "status": self.status,
             "order_index": self.order_index,
+            "path_patterns": list(self.path_patterns or []),
             "created_at": iso(self.created_at),
             "updated_at": iso(self.updated_at),
         }
diff --git a/src/scribe/models/system_usage.py b/src/scribe/models/system_usage.py
new file mode 100644
index 0000000..48e2742
--- /dev/null
+++ b/src/scribe/models/system_usage.py
@@ -0,0 +1,56 @@
+from sqlalchemy import BigInteger, Index, Text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from scribe.models import Base
+from scribe.models.base import CreatedAtMixin, iso
+
+SURFACED = "surfaced"
+PULLED = "pulled"
+
+
+class SystemUsageEvent(Base, CreatedAtMixin):
+    """One row per time a System's rulings were SHOWN to the agent because its
+    files were touched, or the System was PULLED in full (milestone 444).
+
+    The third of the usage tables, after `note_usage_events` and
+    `rule_usage_events`, and separate from both for the reason the rule twin
+    gives: identity at restore. A System id is its own namespace, mapped
+    through the restore's system map; parked in either sibling's id column it
+    would come back attached to whatever note or rule took that number.
+
+    What it answers: whether an area's rulings, delivered by path rather than
+    by a ranker, are then read (`get_system`) — and so whether delivery by
+    path earns its line.
+
+    FK-free on `system_id`, `user_id` and `project_id`, like its siblings:
+    telemetry outlives the row it describes.
+    """
+
+    __tablename__ = "system_usage_events"
+
+    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
+    user_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
+    system_id: Mapped[int] = mapped_column(BigInteger, nullable=False)
+    # 'surfaced' | 'pulled'. Plain Text, no CHECK, like the siblings.
+    event: Mapped[str] = mapped_column(Text, nullable=False)
+    # Which surface produced it — a convention, not a vocabulary (see the
+    # note twin). `grep -rn record_system_ src/` is the authoritative list.
+    source: Mapped[str] = mapped_column(Text, nullable=False)
+    # The project the READER was in, not the System's own.
+    project_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
+
+    __table_args__ = (
+        Index("ix_system_usage_system_event", "system_id", "event"),
+        Index("ix_system_usage_created_at", "created_at"),
+    )
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "created_at": iso(self.created_at),
+            "user_id": self.user_id,
+            "system_id": self.system_id,
+            "event": self.event,
+            "source": self.source,
+            "project_id": self.project_id,
+        }
diff --git a/src/scribe/routes/plugin.py b/src/scribe/routes/plugin.py
index 12b3ed3..4c1ad3d 100644
--- a/src/scribe/routes/plugin.py
+++ b/src/scribe/routes/plugin.py
@@ -194,8 +194,18 @@ async def pre_tool_rules():
                                   different claims about the reader's
                                   context, so they get different lines
                                   (#4100).
+        root, cwd (opt)         — the repo's absolute root and the command's
+                                  working directory. They turn the paths the
+                                  command names into repo-relative ones, for
+                                  the rulings arm (milestone 444).
+        seen_ruling_systems (opt) — comma-separated System ids whose rulings
+                                  were already shown this session, by either
+                                  arm; those get a one-line reference. SHARED
+                                  with /prior-art, like exclude_rule_ids.
 
-    Returns `context`, `rule_ids`, and `checkpoint` (#4214, milestone 419).
+    Returns `context`, `rule_ids`, and `checkpoint` (#4214, milestone 419),
+    plus `ruling_system_ids` — the Systems whose rulings were shown in full on
+    this call — when there were any.
 
     `checkpoint` IS THE ONE PART OF THIS RESPONSE THAT IS NOT A HINT. It is
     empty on almost every call. When present it carries `rule_id`, `title`,
@@ -221,6 +231,9 @@ async def pre_tool_rules():
     result = await plugin_ctx_svc.build_tool_rule_hint(
         g.user.id, tool, command,
         project_id=project_id, exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids,
+        root=(request.args.get("root") or "").strip(),
+        cwd=(request.args.get("cwd") or "").strip(),
+        seen_ruling_systems=_int_list(request.args.get("seen_ruling_systems")),
     )
     return jsonify(result)
 
@@ -265,6 +278,10 @@ async def write_path_prior_art():
                              or `canon:<snippet_id>`) already named this
                              session by the ledger arm (#2900); its own
                              channel, like the two above.
+        seen_ruling_systems (opt) — System ids whose rulings were already shown
+                             this session (milestone 444); shared with
+                             /tool-rules. The response's `ruling_system_ids`
+                             are the ones shown in full on this call.
         (Returns a `checkpoint` block on the same contract as /tool-rules —
         see that endpoint. The write-path HOOK deliberately does not act on
         it: scribe_prior_art.sh carries a tested property that it never
@@ -306,6 +323,7 @@ async def write_path_prior_art():
         repo_key=repo_bindings_svc.normalize_repo_key(repo) if repo else "",
         exclude_derive=exclude_derive,
         exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids,
+        seen_ruling_systems=_int_list(request.args.get("seen_ruling_systems")),
     )
     return jsonify(result)
 
diff --git a/src/scribe/routes/systems.py b/src/scribe/routes/systems.py
index 6acbf18..7021d09 100644
--- a/src/scribe/routes/systems.py
+++ b/src/scribe/routes/systems.py
@@ -82,12 +82,16 @@ async def create_system_route(project_id: int):
     # Exact is mechanical and applied; overlap is a judgment call and is only
     # offered back for the form to present.
     applied = canonical["id"] if canonical and canonical["basis"] == "exact" else None
-    system = await systems_svc.create_system(
-        uid, project_id=project_id, name=data["name"],
-        description=data.get("description"), color=data.get("color"),
-        order_index=data.get("order_index", 0),
-        canonical_id=data.get("canonical_id") or applied,
-    )
+    try:
+        system = await systems_svc.create_system(
+            uid, project_id=project_id, name=data["name"],
+            description=data.get("description"), color=data.get("color"),
+            order_index=data.get("order_index", 0),
+            canonical_id=data.get("canonical_id") or applied,
+            path_patterns=data.get("path_patterns"),
+        )
+    except ValueError as e:
+        return jsonify({"error": str(e)}), 400
     if system is None:
         return jsonify({"error": "Permission denied"}), 403
     out = system.to_dict()
@@ -125,11 +129,14 @@ async def update_system_route(project_id: int, system_id: int):
     if system is None or system.project_id != project_id:
         return not_found("System")
     data = await request.get_json() or {}
-    allowed = {"name", "description", "color", "status", "order_index"}
+    allowed = {"name", "description", "color", "status", "order_index", "path_patterns"}
     fields = {k: v for k, v in data.items() if k in allowed}
     if "status" in fields and fields["status"] not in ("active", "archived"):
         return jsonify({"error": "status must be 'active' or 'archived'"}), 400
-    updated = await systems_svc.update_system(uid, system_id, **fields)
+    try:
+        updated = await systems_svc.update_system(uid, system_id, **fields)
+    except ValueError as e:
+        return jsonify({"error": str(e)}), 400
     if updated is None:
         return not_found("System")
     return jsonify(updated.to_dict())
diff --git a/src/scribe/services/backup.py b/src/scribe/services/backup.py
index c472d94..8a90323 100644
--- a/src/scribe/services/backup.py
+++ b/src/scribe/services/backup.py
@@ -13,6 +13,7 @@ from scribe.models.rule_version import RuleVersion
 from scribe.models.design_system import DesignSystem, DesignToken
 from scribe.models.note_usage import NoteUsageEvent
 from scribe.models.rule_usage import RuleUsageEvent
+from scribe.models.system_usage import SystemUsageEvent
 from scribe.models.retrieval_tuning import RetrievalTuningEvent
 from scribe.models.canonical_system import CanonicalSystem
 from scribe.models.rulebook import RuleRelation, rule_systems as rule_systems_t
@@ -88,8 +89,12 @@ logger = logging.getLogger(__name__)
 # v19 (2026-10) added lesson_no_rule (#4631): the "no rule fits" answer and its
 # reason. Without it a restored lesson that was judged to stand alone reads as
 # never judged, and lands back on the unjudged list.
+# v20 (2026-10) added systems.path_patterns and system_usage_events (milestone
+# 444): the files that are each area, and whether an area's rulings were read
+# once shown. The usage rows restore through the SYSTEM map, for the reason
+# the rule twin restores through the rule map.
 # Bump when the serialized schema changes.
-BACKUP_VERSION = 19
+BACKUP_VERSION = 20
 
 # Every table this backup carries, by its REAL name. Paired with _NOT_INCLUDED
 # below, these two lists must together account for the entire schema — which is
@@ -131,6 +136,9 @@ _BACKED_UP = [
     "lesson_rule_links",
     # v19 (2026-10): "no rule fits" answers (#4631).
     "lesson_no_rule",
+    # v20 (2026-10): System usage telemetry (milestone 444), for the reason
+    # its note and rule twins travel.
+    "system_usage_events",
 ]
 
 # Tables intentionally NOT in the backup, surfaced in the payload so the gap is
@@ -231,6 +239,7 @@ _COLUMN_EXCLUSIONS: dict[str, set[str]] = {
     "note_usage_events": {"id"},
     # Same as the note twin: the surrogate key is re-issued on insert.
     "rule_usage_events": {"id"},
+    "system_usage_events": {"id"},
     # Same again — and everything else travels, because each remaining column
     # is part of the argument: what moved, from what, to what, by whom, why.
     "retrieval_tuning_events": {"id"},
@@ -319,6 +328,7 @@ _IMPORT_COLUMN_EXCLUSIONS: dict[str, set[str]] = {
     "lesson_no_rule": set(),
     "note_usage_events": {"id"},
     "rule_usage_events": {"id"},
+    "system_usage_events": {"id"},
     "retrieval_tuning_events": {"id"},
     "design_systems": {
         "id", "deleted_at", "deleted_batch_id", "created_at", "updated_at",
@@ -387,6 +397,7 @@ def _system_rows(rows, canonical_slugs: dict[int, str]) -> list[dict]:
             "id": r.id, "user_id": r.user_id, "project_id": r.project_id,
             "name": r.name, "description": r.description, "color": r.color,
             "status": r.status, "order_index": r.order_index,
+            "path_patterns": list(r.path_patterns or []),
             "canonical_slug": canonical_slugs.get(r.canonical_id or 0),
         }
         for r in rows
@@ -443,6 +454,17 @@ def _usage_event_rows(rows) -> list[dict]:
     ]
 
 
+def _system_usage_event_rows(rows) -> list[dict]:
+    return [
+        {
+            "user_id": r.user_id, "system_id": r.system_id, "event": r.event,
+            "source": r.source, "project_id": r.project_id,
+            "created_at": r.created_at.isoformat() if r.created_at else None,
+        }
+        for r in rows
+    ]
+
+
 def _rule_usage_event_rows(rows) -> list[dict]:
     return [
         {
@@ -801,6 +823,9 @@ async def export_full_backup() -> dict:
         rule_usage_events = (
             await session.execute(select(RuleUsageEvent))
         ).scalars().all()
+        system_usage_events = (
+            await session.execute(select(SystemUsageEvent))
+        ).scalars().all()
         # Oldest first, so a restored history reads in the order the dials
         # actually moved — the sequence IS the argument when a surface has been
         # walked up and down.
@@ -853,6 +878,7 @@ async def export_full_backup() -> dict:
         "design_tokens": _design_token_rows(design_tokens),
         "note_usage_events": _usage_event_rows(usage_events),
         "rule_usage_events": _rule_usage_event_rows(rule_usage_events),
+        "system_usage_events": _system_usage_event_rows(system_usage_events),
         "retrieval_tuning_events": _retrieval_tuning_event_rows(
             retrieval_tuning_events
         ),
@@ -990,6 +1016,12 @@ async def export_user_backup(user_id: int) -> dict:
         rule_usage_events = (await session.execute(
             select(RuleUsageEvent).where(RuleUsageEvent.rule_id.in_(_rule_ids))
         )).scalars().all() if _rule_ids else []
+        # Scoped through the SYSTEM, for the reason the rule usage events
+        # above are scoped through the rule: `user_id` is who it fired for.
+        _system_ids = [sy.id for sy in systems]
+        system_usage_events = (await session.execute(
+            select(SystemUsageEvent).where(SystemUsageEvent.system_id.in_(_system_ids))
+        )).scalars().all() if _system_ids else []
         # Scoped on user_id, and here that IS the right column — unlike the
         # rule usage events directly above. These record changes to this user's
         # OWN retrieval settings, which is what `user_id` means on this table;
@@ -1053,6 +1085,7 @@ async def export_user_backup(user_id: int) -> dict:
         "design_tokens": _design_token_rows(design_tokens),
         "note_usage_events": _usage_event_rows(usage_events),
         "rule_usage_events": _rule_usage_event_rows(rule_usage_events),
+        "system_usage_events": _system_usage_event_rows(system_usage_events),
         "retrieval_tuning_events": _retrieval_tuning_event_rows(
             retrieval_tuning_events
         ),
@@ -1460,6 +1493,8 @@ def _build_system(row: dict, maps: _Maps) -> System | None:
         color=row.get("color"),
         status=row.get("status", "active"),
         order_index=row.get("order_index", 0),
+        # Absent in a backup taken before milestone 444: no paths, not an error.
+        path_patterns=list(row.get("path_patterns") or []),
         # An unknown slug restores UNMAPPED rather than failing: the System and
         # its records are the payload, the mapping is an aid.
         canonical_id=maps.canonical_by_slug.get(row.get("canonical_slug") or ""),
@@ -1563,6 +1598,22 @@ def _build_rule_usage_event(row: dict, maps: _Maps) -> RuleUsageEvent | None:
     )
 
 
+def _build_system_usage_event(row: dict, maps: _Maps) -> SystemUsageEvent | None:
+    """Resolved through the SYSTEM map — see `_build_rule_usage_event`."""
+    sid = maps.systems.get(row.get("system_id", 0))
+    if sid is None:
+        return None
+    return SystemUsageEvent(
+        user_id=maps.users.get(row.get("user_id") or 0),
+        system_id=sid,
+        event=row.get("event", ""),
+        source=row.get("source", ""),
+        project_id=(maps.projects.get(row["project_id"])
+                    if row.get("project_id") else None),
+        created_at=_dt(row.get("created_at")),
+    )
+
+
 def _build_repo_binding(row: dict, maps: _Maps) -> RepoBinding | None:
     """Small, but losing these means every bound repo quietly stops loading
     its project at session start."""
@@ -1813,6 +1864,7 @@ async def _restore_v2(data: dict) -> dict:
         "settings": 0, "rulebooks": 0, "rulebook_topics": 0, "rules": 0,
         "systems": 0, "record_systems": 0, "design_systems": 0,
         "design_tokens": 0, "note_usage_events": 0, "rule_usage_events": 0,
+        "system_usage_events": 0,
         "repo_bindings": 0,
         "note_supersessions": 0, "code_shapes": 0, "code_shape_events": 0,
         "code_shape_uses": 0, "canonical_systems": 0,
@@ -2102,6 +2154,14 @@ async def _restore_v2(data: dict) -> dict:
             session.add(event)
             stats["rule_usage_events"] += 1
 
+        # And the System twin, after the Systems (step 16 fills their map).
+        for ev in data.get("system_usage_events", []):
+            event = _build_system_usage_event(ev, maps)
+            if event is None:
+                continue
+            session.add(event)
+            stats["system_usage_events"] += 1
+
         # 20. Repo bindings
         for rb_data in data.get("repo_bindings", []):
             binding = _build_repo_binding(rb_data, maps)
diff --git a/src/scribe/services/plugin_context.py b/src/scribe/services/plugin_context.py
index 45bba79..8572e8b 100644
--- a/src/scribe/services/plugin_context.py
+++ b/src/scribe/services/plugin_context.py
@@ -48,6 +48,7 @@ from scribe.services.retrieval_telemetry import record_retrieval
 from scribe.services.settings import get_setting
 from scribe.services.systems import system_names_for
 from scribe.services.text import elide
+from scribe.services import system_rulings as system_rulings_svc
 
 logger = logging.getLogger(__name__)
 
@@ -2187,6 +2188,7 @@ async def build_write_path_hint(
     exclude_derive: list[str] | None = None,
     exclude_rule_ids: list[int] | None = None,
     held_rule_ids: list[int] | None = None,
+    seen_ruling_systems: list[int] | None = None,
 ) -> dict:
     """Prior-art hint for the plugin's PreToolUse hook on Write/Edit.
 
@@ -2253,7 +2255,7 @@ async def build_write_path_hint(
     cfg = await get_writepath_config(user_id)
     empty = {"context": "", "note_ids": [], "sync_note_ids": [], "config": cfg,
              "suggested": [], "divergence": [], "derive": [], "derive_keys": [],
-             "rule_ids": []}
+             "rule_ids": [], "ruling_system_ids": []}
     path = (path or "").strip()
     if not cfg["enabled"] or not path:
         return empty
@@ -2590,9 +2592,21 @@ async def build_write_path_hint(
     design_text, design_dedup = await _design_arm(
         user_id, project_id, path, set(exclude_derive or []),
     )
+    # The rulings arm (milestone 444), decided here for the design arm's
+    # reasons: a lookup by path, so a write that matched no prior art still
+    # carries its area's rulings, and it never switches the ranked arms on.
+    rulings = await system_rulings_svc.rulings_for_paths(
+        user_id, project_id, [path], seen=seen_ruling_systems,
+        source="rulings_write_path",
+    )
     if not staleness and not synced and not menu and not suggested and not divergence and not derive:
-        if design_text:
-            return {**empty, "context": design_text, "derive_keys": [design_dedup]}
+        if design_text or rulings["lines"]:
+            return {
+                **empty,
+                "context": "\n".join(rulings["lines"] + ([design_text] if design_text else [])),
+                "derive_keys": [design_dedup] if design_dedup else [],
+                "ruling_system_ids": rulings["system_ids"],
+            }
         return empty
 
     owners = await owner_names_for({
@@ -2614,7 +2628,9 @@ async def build_write_path_hint(
     # Seeded with the staleness line, which is decided above the early
     # return and so cannot wait for this list to exist.
     lines: list[str] = list(staleness)
-    # First after staleness: it BINDS, where everything below is prior art.
+    # First after staleness: rulings and the design system BIND, where
+    # everything below is prior art.
+    lines.extend(rulings["lines"])
     if design_text:
         lines.append(design_text)
     sync_note_ids: list[int] = []
@@ -2890,6 +2906,7 @@ async def build_write_path_hint(
         ),
         "rule_ids": rule_ids,
         "checkpoint": checkpoint,
+        "ruling_system_ids": rulings["system_ids"],
     }
 
 
@@ -2901,18 +2918,46 @@ async def build_tool_rule_hint(
     project_id: int = 0,
     exclude_rule_ids: list[int] | None = None,
     held_rule_ids: list[int] | None = None,
+    root: str = "",
+    cwd: str = "",
+    seen_ruling_systems: list[int] | None = None,
 ) -> dict:
     """Standing rules that may apply to the action about to be taken — matched
     directly (`_tool_rule_hint`, where the design is written), then reached
-    through a linked lesson (`_rules_via_lessons`, #4633)."""
+    through a linked lesson (`_rules_via_lessons`, #4633) — and the rulings of
+    any area whose files the command names (milestone 444).
+
+    `root` and `cwd` are the repo's absolute root and the command's working
+    directory, from the hook; they are what turn the paths a command names
+    into the repo-relative paths a System's patterns are written in."""
     out = await _tool_rule_hint(
         user_id, tool_name, command, project_id=project_id,
         exclude_rule_ids=exclude_rule_ids, held_rule_ids=held_rule_ids,
     )
-    return await _add_rules_via_lessons(
+    out = await _add_rules_via_lessons(
         user_id, out, project_id=project_id, exclude_rule_ids=exclude_rule_ids,
         held_rule_ids=held_rule_ids, where=f"to this {tool_name} call",
     )
+    # Its own arm, not part of the rule search: a lookup by path, with no
+    # floor and no budget, so it adds to the rule lines rather than competing
+    # with them. First, because a ruling is the operator's own decision.
+    # `ruling_system_ids` is set only when a ruling was shown: this arm fires
+    # on every command, and the hook reads an absent list as an empty one.
+    try:
+        paths = system_rulings_svc.command_paths(command, root=root, cwd=cwd) if project_id else []
+        if paths and (await get_writepath_config(user_id)).get("enabled"):
+            rulings = await system_rulings_svc.rulings_for_paths(
+                user_id, project_id, paths,
+                seen=seen_ruling_systems, source="rulings_pre_tool",
+            )
+            if rulings["lines"]:
+                out["context"] = "\n".join(
+                    rulings["lines"] + ([out["context"]] if out.get("context") else [])
+                )
+                out["ruling_system_ids"] = rulings["system_ids"]
+    except Exception:
+        logger.debug("pre-tool rulings arm failed", exc_info=True)
+    return out
 
 
 async def _tool_rule_hint(
diff --git a/src/scribe/services/system_rulings.py b/src/scribe/services/system_rulings.py
new file mode 100644
index 0000000..2e58483
--- /dev/null
+++ b/src/scribe/services/system_rulings.py
@@ -0,0 +1,196 @@
+"""An area's rulings, delivered when its files are touched (milestone 444).
+
+A RULING is the operator's decision about how one area of the work must behave.
+It lives in a `Rulings` section at the end of the area's System description
+(writing-records.md says how one is written). The description already rides
+every record filed under the System; this module is the other half: the first
+command or edit in a session that touches the System's files
+(`System.path_patterns`) shows its rulings, one line per System.
+
+A LOOKUP, NOT A SEARCH. A shell command scores against prose decisions at noise
+level, so nothing here is ranked: a path either falls under a System's
+patterns or it does not. It takes no budget and no floor from the retrieval
+arms beside it, and writes no retrieval_logs row — there is no score
+distribution for it to join. Its surfacings go to `system_usage_events`.
+
+ONCE IN FULL, THEN A REFERENCE (the #3750 shape). The hook keeps the Systems
+already shown this session and passes them back; a repeat renders as one short
+line rather than the rulings again, and is not counted as a surfacing.
+
+Fails open everywhere: a delivery aid must never break the act it rides on.
+"""
+from __future__ import annotations
+
+import logging
+import posixpath
+import re
+import shlex
+
+from scribe.services import systems as systems_svc
+from scribe.services.system_usage import record_system_surfaced
+from scribe.services.text import elide
+
+logger = logging.getLogger(__name__)
+
+# The section heading: `Rulings`, optionally as a markdown heading, bold, or
+# with a trailing colon. The LAST one wins — the section sits at the end.
+_HEADING = re.compile(r"^[ \t]*(?:#{1,6}[ \t]*)?\**Rulings\**[ \t]*:?[ \t]*$", re.I | re.M)
+_BULLET = re.compile(r"^[ \t]*[-*][ \t]+(.*)$")
+
+# Per line, so one System with a long list cannot crowd the others out.
+RULING_CHARS = 300
+RULINGS_PER_SYSTEM = 8
+
+# A command is not a file list: these bound how much of it is read as paths.
+_MAX_PATHS = 40
+_LINE_SUFFIX = re.compile(r":\d+(?::\d+)?$")
+_HAS_EXTENSION = re.compile(r"\.[A-Za-z0-9]{1,10}$")
+_ASSIGNMENT = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*=")
+
+
+def parse_rulings(description: str | None) -> list[str]:
+    """The rulings in a System description, one string per ruling.
+
+    A bullet under the last `Rulings` heading is a ruling; an indented line
+    after one continues it. The section ends at the first line that is
+    neither — a heading or paragraph written after it is not a ruling.
+    """
+    text = description or ""
+    found = list(_HEADING.finditer(text))
+    if not found:
+        return []
+    out: list[str] = []
+    for line in text[found[-1].end():].splitlines():
+        if not line.strip():
+            continue
+        bullet = _BULLET.match(line)
+        if bullet:
+            if bullet.group(1).strip():
+                out.append(bullet.group(1).strip())
+        elif out and line[:1] in (" ", "\t"):
+            out[-1] = f"{out[-1]} {line.strip()}"
+        else:
+            break
+    return out
+
+
+def _relative(token: str, root: str, cwd_rel: str) -> str:
+    """`token` as a repo-relative path, or "" when it is not one."""
+    if token.startswith("/"):
+        if not root or not token.startswith(root.rstrip("/") + "/"):
+            return ""
+        token = token[len(root.rstrip("/")) + 1:]
+    elif cwd_rel:
+        token = f"{cwd_rel}/{token}"
+    path = posixpath.normpath(token)
+    if path in (".", "") or path == ".." or path.startswith("../"):
+        return ""
+    return path
+
+
+def command_paths(command: str, *, root: str = "", cwd: str = "") -> list[str]:
+    """The repo-relative paths a shell command names, in order, deduplicated.
+
+    Reads and writes alike: a session forms its picture of an area by reading
+    it, which is exactly when that area's rulings should reach it. A token is
+    taken as a path when it has a `/` or a file extension; flags, URLs and
+    globs are not paths. `root` is the repo's absolute root and `cwd` the
+    command's working directory, both from the hook — an absolute path
+    outside the root, or a relative one that climbs out of it, is dropped.
+    """
+    command = command or ""
+    try:
+        tokens = shlex.split(command, comments=False, posix=True)
+    except ValueError:
+        tokens = command.split()
+    root = (root or "").rstrip("/")
+    cwd_rel = ""
+    if root and cwd:
+        cwd = cwd.rstrip("/")
+        if cwd.startswith(root + "/"):
+            cwd_rel = cwd[len(root) + 1:]
+    out: list[str] = []
+    for raw in tokens:
+        token = raw.strip().strip("'\"").rstrip(";,)|&")
+        if token.startswith("-"):
+            if "=" not in token:
+                continue
+            token = token.split("=", 1)[1]
+        elif _ASSIGNMENT.match(token):
+            token = token.split("=", 1)[1]
+        if not token or "://" in token or any(c in token for c in "*?[]{}$`<>"):
+            continue
+        # `file.py:120` and a test id `file.py::test_x` name the file.
+        token = _LINE_SUFFIX.sub("", token.split("::", 1)[0])
+        if "/" not in token and not _HAS_EXTENSION.search(token):
+            continue
+        path = _relative(token, root, cwd_rel)
+        if path and path not in out:
+            out.append(path)
+            if len(out) >= _MAX_PATHS:
+                break
+    return out
+
+
+def _full_line(system, path: str, rulings: list[str]) -> str:
+    shown = [elide(r, RULING_CHARS)[0] for r in rulings[:RULINGS_PER_SYSTEM]]
+    more = len(rulings) - len(shown)
+    listed = " ".join(f"({i}) {r}" for i, r in enumerate(shown, 1))
+    if more > 0:
+        listed += f" (+{more} more in `get_system({system.id})`)"
+    return (
+        f"> Rulings for `{path}` — the operator's decisions about "
+        f"{system.name} (System {system.id}): {listed} "
+        "Work here keeps to them; something that would depart from one is a "
+        "question for the operator, not an option to choose. "
+        "(Shown once per session.)"
+    )
+
+
+def _reference_line(system, path: str) -> str:
+    return (
+        f"> `{path}` is in {system.name} (System {system.id}) — its rulings "
+        "were shown earlier this session and still apply."
+    )
+
+
+async def rulings_for_paths(
+    user_id: int,
+    project_id: int,
+    paths: list[str],
+    *,
+    seen: list[int] | set[int] | None = None,
+    source: str,
+) -> dict:
+    """Rulings lines for the Systems whose files `paths` touch.
+
+    Returns {"lines": [...], "system_ids": [...]} — `system_ids` are the
+    Systems shown IN FULL on this call, for the hook to add to the session's
+    seen list and for the usage ledger; a System in `seen` gets a reference
+    line and is in neither. A System with patterns but no rulings says
+    nothing: there is no decision to deliver, and the charter already rides
+    its records.
+    """
+    out: dict = {"lines": [], "system_ids": []}
+    if not project_id or not paths:
+        return out
+    try:
+        already = {int(s) for s in (seen or [])}
+        for system, hit in await systems_svc.systems_for_paths(user_id, project_id, paths):
+            rulings = parse_rulings(system.description)
+            if not rulings:
+                continue
+            if system.id in already:
+                out["lines"].append(_reference_line(system, hit[0]))
+            else:
+                out["lines"].append(_full_line(system, hit[0], rulings))
+                out["system_ids"].append(system.id)
+        if out["system_ids"]:
+            record_system_surfaced(
+                user_id=user_id, system_ids=out["system_ids"], source=source,
+                project_id=project_id,
+            )
+    except Exception:
+        logger.debug("rulings arm failed", exc_info=True)
+        return {"lines": [], "system_ids": []}
+    return out
diff --git a/src/scribe/services/system_usage.py b/src/scribe/services/system_usage.py
new file mode 100644
index 0000000..61c5967
--- /dev/null
+++ b/src/scribe/services/system_usage.py
@@ -0,0 +1,67 @@
+"""System usage telemetry — were an area's rulings read once shown?
+
+The twin of `note_usage` and `rule_usage` for Systems (milestone 444). The
+rulings arm shows a System's rulings when a command or edit touches the
+System's files; a pull is somebody then opening the System (`get_system`). The
+ratio says whether delivering rulings by path earns its line.
+
+Fire-and-forget like its siblings: telemetry never adds latency to, or
+breaks, the surface it observes, and failures report through the shared
+canary rather than vanishing.
+"""
+from __future__ import annotations
+
+import logging
+
+from scribe.models import async_session
+from scribe.models.system_usage import PULLED, SURFACED, SystemUsageEvent
+from scribe.services.background import report_telemetry_failure, spawn
+
+logger = logging.getLogger(__name__)
+
+
+async def _insert_events(rows: list[dict]) -> None:
+    """Persist usage rows. Best-effort: failures degrade, visibly."""
+    try:
+        async with async_session() as session:
+            session.add_all([SystemUsageEvent(**row) for row in rows])
+            await session.commit()
+    except Exception:
+        await report_telemetry_failure("system_usage", "write")
+
+
+def _rows(user_id, system_ids, event: str, source: str, project_id) -> list[dict]:
+    pid = int(project_id or 0) or None
+    return [
+        {"user_id": user_id, "system_id": int(sid), "event": event,
+         "source": source, "project_id": pid}
+        for sid in system_ids
+    ]
+
+
+def record_system_surfaced(
+    *, user_id: int | None, system_ids: list[int], source: str,
+    project_id: int | None = None,
+) -> None:
+    """Fire-and-forget: these Systems' rulings were shown in full. A repeat
+    rendered as a short reference is not a surfacing and is not recorded."""
+    try:
+        rows = _rows(user_id, system_ids, SURFACED, source, project_id)
+    except Exception:
+        logger.debug("system usage payload build failed", exc_info=True)
+        return
+    if rows:
+        spawn(_insert_events(rows), site="system_usage_write")
+
+
+def record_system_pulled(
+    *, user_id: int | None, system_id: int, source: str,
+    project_id: int | None = None,
+) -> None:
+    """Fire-and-forget: a System was opened in full."""
+    try:
+        rows = _rows(user_id, [system_id], PULLED, source, project_id)
+    except Exception:
+        logger.debug("system usage payload build failed", exc_info=True)
+        return
+    spawn(_insert_events(rows), site="system_usage_write")
diff --git a/src/scribe/services/systems.py b/src/scribe/services/systems.py
index 293cd7a..9050cbc 100644
--- a/src/scribe/services/systems.py
+++ b/src/scribe/services/systems.py
@@ -7,6 +7,7 @@ many-to-many through record_systems, mutable over time.
 """
 import logging
 from datetime import datetime, timezone
+from pathlib import PurePosixPath
 
 from sqlalchemy import delete, func, select
 
@@ -31,6 +32,87 @@ def local_name_key(name: str) -> str:
     return " ".join(name.split()).lower()
 
 
+# Bounds on what one System may claim. Generous for a real area — a handful of
+# directories and the odd stray file — and small enough that a pasted file
+# listing is refused rather than stored as the area's definition.
+MAX_PATH_PATTERNS = 50
+MAX_PATH_PATTERN_LENGTH = 300
+
+
+def normalize_repo_path(path: str) -> str:
+    """A path as the patterns see it: relative to the repo root, `/`-separated.
+
+    Shared by the patterns and the paths matched against them, so the two can
+    never disagree about whether `./src/x.py` and `src/x.py` are one file.
+    """
+    out = (path or "").strip().replace("\\", "/")
+    while out.startswith("./"):
+        out = out[2:]
+    out = out.lstrip("/")
+    while len(out) > 1 and out.endswith("/"):
+        out = out[:-1]
+    return out
+
+
+def normalize_path_patterns(patterns) -> list[str]:
+    """Validate and tidy a System's path patterns; ValueError says what is wrong.
+
+    Blank entries are dropped and repeats collapse, keeping the first-written
+    order. A pattern that climbs out of the repo (`..`) is refused rather than
+    dropped: it can never match, and storing it would read as coverage.
+    """
+    if patterns is None:
+        return []
+    if isinstance(patterns, str) or not isinstance(patterns, (list, tuple)):
+        raise ValueError("path_patterns must be a list of glob strings")
+    out: list[str] = []
+    for raw in patterns:
+        if not isinstance(raw, str):
+            raise ValueError("path_patterns must be a list of glob strings")
+        pattern = normalize_repo_path(raw)
+        if not pattern:
+            continue
+        if len(pattern) > MAX_PATH_PATTERN_LENGTH:
+            raise ValueError(
+                f"path pattern longer than {MAX_PATH_PATTERN_LENGTH} characters: "
+                f"{pattern[:60]}…"
+            )
+        if ".." in pattern.split("/"):
+            raise ValueError(
+                f"path pattern {pattern!r} leaves the repo — patterns are "
+                "relative to the repo root"
+            )
+        if pattern not in out:
+            out.append(pattern)
+    if len(out) > MAX_PATH_PATTERNS:
+        raise ValueError(
+            f"{len(out)} path patterns; a System takes at most "
+            f"{MAX_PATH_PATTERNS} — name directories with `**` rather than "
+            "listing their files"
+        )
+    return out
+
+
+def path_matches(pattern: str, path: str) -> bool:
+    """Whether a repo-relative path falls under one pattern.
+
+    Glob semantics are `PurePosixPath.full_match`: `*` stays inside one path
+    segment, `**` spans any number of them, and case counts. A pattern with
+    no wildcard that names a directory covers everything under it, so
+    `src/billing` means the directory the way a person writing it means it.
+    """
+    path = normalize_repo_path(path)
+    if not path or not pattern:
+        return False
+    candidate = PurePosixPath(path)
+    return candidate.full_match(pattern) or candidate.full_match(f"{pattern}/**")
+
+
+def matching_patterns(patterns, path: str) -> list[str]:
+    """The patterns among `patterns` that `path` falls under, in their order."""
+    return [p for p in (patterns or []) if path_matches(p, path)]
+
+
 async def assess_system_name(user_id: int, project_id: int, name: str) -> dict:
     """What BOTH doors must know before minting a System name (milestone 307).
 
@@ -154,13 +236,18 @@ async def create_system(
     color: str | None = None,
     order_index: int = 0,
     canonical_id: int | None = None,
+    path_patterns: list[str] | None = None,
 ) -> System | None:
     """Create a System. None if the user can't write the project.
 
     `canonical_id` maps the new System onto the global catalog; leaving it None
     is fine — an unmapped System is fully usable, and the mapping can be
     proposed later (services/canonical_systems.propose_mappings).
+
+    `path_patterns` are validated here, so every door refuses the same bad
+    pattern with the same message (ValueError).
     """
+    patterns = normalize_path_patterns(path_patterns)
     if not await access.can_write_project(user_id, project_id):
         return None
     async with async_session() as session:
@@ -172,6 +259,7 @@ async def create_system(
             color=color,
             order_index=order_index,
             canonical_id=canonical_id,
+            path_patterns=patterns,
         )
         session.add(system)
         await session.commit()
@@ -209,13 +297,40 @@ async def list_systems(
         return list(result.scalars().all())
 
 
+async def systems_for_paths(
+    user_id: int, project_id: int, paths: list[str],
+) -> list[tuple[System, list[str]]]:
+    """The project's active Systems whose patterns cover any of `paths`.
+
+    Each comes with the paths it matched, in the order given. A path can match
+    several Systems — areas overlap, and every one it belongs to answers for
+    it — so nothing here picks a winner. Systems with no patterns never match:
+    an area that has not named its files is not claiming all of them.
+    """
+    wanted = [p for p in (normalize_repo_path(x) for x in paths or []) if p]
+    if not wanted:
+        return []
+    out: list[tuple[System, list[str]]] = []
+    for system in await list_systems(user_id, project_id):
+        patterns = system.path_patterns or []
+        if not patterns:
+            continue
+        hit = [p for p in wanted if matching_patterns(patterns, p)]
+        if hit:
+            out.append((system, hit))
+    return out
+
 async def update_system(user_id: int, system_id: int, **fields: object) -> System | None:
     """Update a System if the user can write its project."""
     # canonical_id is deliberately NOT settable here: canonical_systems.
     # set_system_canonical is its single writer, because it also validates the
     # catalog entry is live. Two entry points onto one column is the drift this
     # table exists to end.
-    allowed = {"name", "description", "color", "status", "order_index"}
+    allowed = {"name", "description", "color", "status", "order_index", "path_patterns"}
+    # Validated before anything is read, so a refused pattern changes nothing.
+    # `[]` is a value here, not "leave unchanged": it clears the paths.
+    if fields.get("path_patterns") is not None:
+        fields["path_patterns"] = normalize_path_patterns(fields["path_patterns"])
     async with async_session() as session:
         system = await session.get(System, system_id)
         if system is None or system.deleted_at is not None:
diff --git a/tests/conftest.py b/tests/conftest.py
index 06e0fe6..234db00 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -116,6 +116,21 @@ def _no_system_labels():
         yield
 
 
+@pytest.fixture(autouse=True)
+def _no_rulings_arm():
+    """Stub the rulings arm both PreToolUse builders run (milestone 444).
+
+    Autouse for _no_system_labels' reason: every write-path and tool-rule
+    test with a project in scope reaches it, and its first act is reading the
+    project's Systems from Postgres. Stubbed to "no area's files touched".
+    tests/test_system_rulings.py binds the real function at import time,
+    before this patch runs.
+    """
+    with patch("scribe.services.system_rulings.rulings_for_paths",
+               AsyncMock(return_value={"lines": [], "system_ids": []})):
+        yield
+
+
 @pytest.fixture(autouse=True)
 def _no_task_log_arm():
     """Stub the task-log read arm that get_task / list_tasks / get_milestone
diff --git a/tests/test_guidance_ownership.py b/tests/test_guidance_ownership.py
index 1779915..7fd8b70 100644
--- a/tests/test_guidance_ownership.py
+++ b/tests/test_guidance_ownership.py
@@ -205,6 +205,9 @@ TOPICS: tuple[Topic, ...] = (
     Topic("code says what a thing does, not what was wanted", U,
           ("rulings", "unconfirmed"),
           "code tells you what a thing does, not what was wanted"),
+    Topic("a System names its files, and tagging work keeps them current", U,
+          ("path_patterns", "update_system"),
+          "which files are which area is your call"),
     # ── process arcs — owned by their skills ──
     Topic("plan in a milestone, steps created together", "skill:writing-plans", ("start_planning", "{{ref:"),
           "a milestone earns its place when the work has an arc", index=("start_planning",)),
diff --git a/tests/test_mcp_tool_systems.py b/tests/test_mcp_tool_systems.py
index 6f8c79e..b60c543 100644
--- a/tests/test_mcp_tool_systems.py
+++ b/tests/test_mcp_tool_systems.py
@@ -101,6 +101,23 @@ async def test_get_system_splits_records_by_kind():
     assert [r["id"] for r in result["notes"]] == [12]
 
 
+@pytest.mark.asyncio
+async def test_path_patterns_reach_the_service_from_both_tools():
+    """Omitted means unchanged; an empty list is a value — it clears them."""
+    with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
+         patch("scribe.mcp.tools.systems.systems_svc") as svc:
+        svc.assess_system_name = AsyncMock(return_value=_NO_MATCH)
+        svc.create_system = AsyncMock(return_value=fake_system(name="Billing"))
+        svc.update_system = AsyncMock(return_value=fake_system(name="Billing"))
+        from scribe.mcp.tools.systems import create_system, update_system
+        await create_system(project_id=5, name="Billing", path_patterns=["src/billing"])
+        assert svc.create_system.await_args.kwargs["path_patterns"] == ["src/billing"]
+        await update_system(system_id=1, name="Billing")
+        assert "path_patterns" not in svc.update_system.await_args.kwargs
+        await update_system(system_id=1, path_patterns=[])
+        assert svc.update_system.await_args.kwargs["path_patterns"] == []
+
+
 @pytest.mark.asyncio
 async def test_update_system_not_found_raises():
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
diff --git a/tests/test_rule_usage_wiring.py b/tests/test_rule_usage_wiring.py
index 91dde55..a397abe 100644
--- a/tests/test_rule_usage_wiring.py
+++ b/tests/test_rule_usage_wiring.py
@@ -744,7 +744,9 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
     handler = route.split("async def pre_tool_rules")[1].split("\n@plugin_bp")[0]
 
     sent = set(re.findall(r"[?&]([a-z_]+)=", hook))
-    assert sent == {"tool", "command", "exclude_rule_ids"}, sent
+    # `root` and `cwd` (milestone 444): where the command runs, so the paths it
+    # names can be made repo-relative for the rulings arm.
+    assert sent == {"tool", "command", "exclude_rule_ids", "root", "cwd"}, sent
 
     # The project-scope key is the shared helper's to choose (#4085): the hook
     # splices in `scribe_scope_query`'s output, which is `repo=` inside a git
@@ -763,6 +765,12 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
     assert "printf '&held_rule_ids=" in defs, (
         "the opened ledger's query key is no longer spelled in the helper"
     )
+    # The rulings ledger, shared with the write-path hook (milestone 444) —
+    # spelled once in its helper for the same reason.
+    assert "scribe_rulings_query" in hook, "hook no longer sends the rulings ledger"
+    assert "printf '&seen_ruling_systems=" in defs, (
+        "the rulings ledger's query key is no longer spelled in the helper"
+    )
 
     # Both scope keys are read by the shared _project_scope() helper, not inline.
     assert "_project_scope()" in handler
@@ -776,7 +784,7 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
     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"):
+    for arg in ("tool", "command", "exclude_rule_ids", "root", "cwd", "seen_ruling_systems"):
         assert f'request.args.get("{arg}")' in handler, (
             f"the hook sends {arg!r} and the route never reads it"
         )
diff --git a/tests/test_services_backup.py b/tests/test_services_backup.py
index a7ee02e..b1c78df 100644
--- a/tests/test_services_backup.py
+++ b/tests/test_services_backup.py
@@ -27,7 +27,7 @@ def test_backup_version_is_current():
 
     (Named for the number it asserted until v10, which is exactly the drift a
     name-carrying-a-value invites; it now says what it checks.)"""
-    assert backup.BACKUP_VERSION == 19
+    assert backup.BACKUP_VERSION == 20
 
 
 def _exportable_note(**over):
@@ -139,6 +139,7 @@ def _column_guard_targets():
     from scribe.models.note_supersession import NoteSupersession
     from scribe.models.note_usage import NoteUsageEvent
     from scribe.models.rule_usage import RuleUsageEvent
+    from scribe.models.system_usage import SystemUsageEvent
     from scribe.models.retrieval_tuning import RetrievalTuningEvent
     from scribe.models.note_version import NoteVersion
     from scribe.models.rule_version import RuleVersion
@@ -172,6 +173,7 @@ def _column_guard_targets():
         "lesson_no_rule": (LessonNoRule, backup._lesson_no_rule_rows),
         "note_usage_events": (NoteUsageEvent, backup._usage_event_rows),
         "rule_usage_events": (RuleUsageEvent, backup._rule_usage_event_rows),
+        "system_usage_events": (SystemUsageEvent, backup._system_usage_event_rows),
         "retrieval_tuning_events": (
             RetrievalTuningEvent, backup._retrieval_tuning_event_rows,
         ),
@@ -290,6 +292,7 @@ def _import_guard_targets():
         "lesson_no_rule": backup._build_lesson_no_rule,
         "note_usage_events": backup._build_usage_event,
         "rule_usage_events": backup._build_rule_usage_event,
+        "system_usage_events": backup._build_system_usage_event,
         "retrieval_tuning_events": backup._build_retrieval_tuning_event,
         "design_systems": backup._build_design_system,
         "design_tokens": backup._build_design_token,
@@ -543,7 +546,9 @@ async def test_export_full_backup_contains_every_declared_section():
                 # v18: which rule each lesson is an instance of.
                 "lesson_rule_links",
                 # v19: the lessons judged to fall under no rule.
-                "lesson_no_rule"):
+                "lesson_no_rule",
+                # v20: whether an area's rulings were read once shown.
+                "system_usage_events"):
         assert key in out, f"missing export section: {key}"
         assert out[key] == []
 
diff --git a/tests/test_services_systems.py b/tests/test_services_systems.py
index a15decf..7ffcc6a 100644
--- a/tests/test_services_systems.py
+++ b/tests/test_services_systems.py
@@ -126,3 +126,127 @@ async def test_assess_fails_open_so_a_naming_aid_cannot_block_a_create():
 async def test_assess_says_nothing_about_a_nameless_system():
     from scribe.services.systems import assess_system_name
     assert await assess_system_name(1, 5, "   ") == {"duplicate": None, "canonical": None}
+
+
+# ── path patterns — the files that ARE the area (milestone 444, #4756) ──
+
+def test_patterns_are_tidied_to_repo_relative_and_deduplicated():
+    from scribe.services.systems import normalize_path_patterns
+    out = normalize_path_patterns([
+        "  ./src/billing/ ", "/src/billing", "", "src\\api\\*.py", "  ",
+        "frontend/src/**/Billing*.vue",
+    ])
+    assert out == ["src/billing", "src/api/*.py", "frontend/src/**/Billing*.vue"]
+    assert normalize_path_patterns(None) == []
+    assert normalize_path_patterns([]) == []
+
+
+@pytest.mark.parametrize("bad", [
+    "src/billing",                 # a bare string, not a list
+    ["../other-repo/src"],          # leaves the repo
+    ["src/../../etc"],
+    [42],
+    ["x" * 301],
+    [f"src/f{i}.py" for i in range(51)],
+])
+def test_patterns_that_cannot_mean_an_area_are_refused(bad):
+    from scribe.services.systems import normalize_path_patterns
+    with pytest.raises(ValueError):
+        normalize_path_patterns(bad)
+
+
+@pytest.mark.parametrize("pattern,path,expected", [
+    # A plain directory covers everything under it, at any depth.
+    ("src/billing", "src/billing/invoice.py", True),
+    ("src/billing", "src/billing/deep/er/x.py", True),
+    ("src/billing", "src/billing", True),
+    ("src/billing", "src/billingual/x.py", False),
+    # `*` stays inside one segment; `**` spans any number, including none.
+    ("src/*.py", "src/app.py", True),
+    ("src/*.py", "src/pkg/app.py", False),
+    ("src/**/*.py", "src/pkg/sub/app.py", True),
+    ("src/**/*.py", "src/app.py", True),
+    ("**/Billing*.vue", "frontend/src/components/BillingCard.vue", True),
+    # Case counts, and the path is read the way the pattern was written.
+    ("src/billing", "Src/billing/x.py", False),
+    ("src/billing", "./src/billing/x.py", True),
+    ("src/billing", "", False),
+])
+def test_path_matches(pattern, path, expected):
+    from scribe.services.systems import path_matches
+    assert path_matches(pattern, path) is expected
+
+
+@pytest.mark.asyncio
+async def test_systems_for_paths_returns_every_area_a_path_belongs_to():
+    """Areas overlap, and each one a path belongs to answers for it — the
+    lookup never picks a winner. A System that named no files claims none."""
+    api = MagicMock(id=1, path_patterns=["src/scribe/routes", "src/scribe/mcp/tools"])
+    data = MagicMock(id=2, path_patterns=["src/scribe/models", "src/scribe/**/systems.py"])
+    unnamed = MagicMock(id=3, path_patterns=[])
+    with patch("scribe.services.systems.list_systems",
+               AsyncMock(return_value=[api, data, unnamed])):
+        from scribe.services.systems import systems_for_paths
+        out = await systems_for_paths(1, 5, [
+            "src/scribe/routes/systems.py", "./README.md", "",
+        ])
+    assert [(s.id, paths) for s, paths in out] == [
+        (1, ["src/scribe/routes/systems.py"]),
+        (2, ["src/scribe/routes/systems.py"]),
+    ]
+
+
+@pytest.mark.asyncio
+async def test_systems_for_paths_with_no_paths_reads_nothing():
+    lister = AsyncMock(return_value=[])
+    with patch("scribe.services.systems.list_systems", lister):
+        from scribe.services.systems import systems_for_paths
+        assert await systems_for_paths(1, 5, ["", "  "]) == []
+    lister.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_update_refuses_a_bad_pattern_before_touching_the_row():
+    with patch("scribe.services.systems.async_session") as mock_cls:
+        from scribe.services.systems import update_system
+        with pytest.raises(ValueError):
+            await update_system(1, 9, path_patterns=["../elsewhere"])
+    mock_cls.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_update_with_an_empty_list_clears_the_patterns():
+    """`[]` is a value, not "leave unchanged" — the service skips only None."""
+    system = MagicMock(deleted_at=None, project_id=5, path_patterns=["src/old"])
+    session = make_mock_session()
+    session.get = AsyncMock(return_value=system)
+    with patch("scribe.services.systems.async_session", return_value=session), \
+         patch("scribe.services.systems.access") as acc, \
+         patch("scribe.services.systems.embed_system"):
+        acc.can_write_project = AsyncMock(return_value=True)
+        from scribe.services.systems import update_system
+        await update_system(1, 9, path_patterns=[])
+    assert system.path_patterns == []
+
+
+@pytest.mark.asyncio
+async def test_create_stores_tidied_patterns():
+    mock_session = make_mock_session()
+    captured = {}
+    mock_session.add = MagicMock(side_effect=lambda obj: captured.update(
+        patterns=getattr(obj, "path_patterns", "MISSING")))
+    with patch("scribe.services.systems.async_session", return_value=mock_session), \
+         patch("scribe.services.systems.access") as acc, \
+         patch("scribe.services.systems.embed_system"):
+        acc.can_write_project = AsyncMock(return_value=True)
+        from scribe.services.systems import create_system
+        await create_system(1, 5, "Billing", path_patterns=["./src/billing/"])
+    assert captured["patterns"] == ["src/billing"]
+
+
+def test_system_to_dict_carries_its_patterns():
+    from scribe.models.system import System
+    system = System(id=1, user_id=1, project_id=5, name="Billing",
+                    path_patterns=["src/billing"])
+    assert system.to_dict()["path_patterns"] == ["src/billing"]
+    assert System(id=2, user_id=1, project_id=5, name="X").to_dict()["path_patterns"] == []
diff --git a/tests/test_system_rulings.py b/tests/test_system_rulings.py
new file mode 100644
index 0000000..fe94da9
--- /dev/null
+++ b/tests/test_system_rulings.py
@@ -0,0 +1,241 @@
+"""An area's rulings reach the work that touches its files (milestone 444, #4757).
+
+These pin:
+
+- WHAT A RULING IS, as read: a bullet under the last `Rulings` heading of a
+  System's description, wrapped lines joined, the section ending at the first
+  line that is neither.
+- WHICH PATHS A COMMAND NAMES: reads and writes alike, relative to the repo
+  root whatever the command's cwd; flags, URLs and globs are not paths, and a
+  path outside the repo is nobody's area.
+- THE ARM: a lookup, not a search. No rulings or no patterns says nothing; a
+  path in two areas hears both; a repeat is one short reference line and is
+  neither counted as a surfacing nor handed back as newly shown.
+- THE WIRING: both PreToolUse builders carry it, ahead of what they rank.
+"""
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from scribe.services import plugin_context as pc
+from scribe.services import system_rulings as sr
+# Bound at import, before conftest's autouse stub replaces the module attribute.
+from scribe.services.system_rulings import rulings_for_paths as real_rulings_for_paths
+from tests.helpers import writepath_cfg
+
+DOWNLOADS = """Fetching and keeping downloads healthy: stalls, retries, the blocklist.
+
+Rulings
+- Failed work is retried until it succeeds; no attempt limit. (Operator, 2026-09-19, #1234)
+- A blocklisted release falls off the list after a while
+  and may be tried again. (Operator, 2026-09-20, #1240)
+"""
+
+
+def _system(sid, name, description, patterns):
+    return SimpleNamespace(id=sid, name=name, description=description, path_patterns=patterns)
+
+
+# ── reading the section ──────────────────────────────────────────────────
+
+
+def test_rulings_are_the_bullets_under_the_heading_with_wrapped_lines_joined():
+    assert sr.parse_rulings(DOWNLOADS) == [
+        "Failed work is retried until it succeeds; no attempt limit. (Operator, 2026-09-19, #1234)",
+        "A blocklisted release falls off the list after a while and may be tried again. "
+        "(Operator, 2026-09-20, #1240)",
+    ]
+
+
+@pytest.mark.parametrize("heading", ["Rulings", "## Rulings", "**Rulings**", "Rulings:", "### rulings"])
+def test_the_heading_may_be_written_several_ways(heading):
+    assert sr.parse_rulings(f"Charter.\n\n{heading}\n- One. (Operator)\n") == ["One. (Operator)"]
+
+
+def test_no_section_and_an_empty_description_have_no_rulings():
+    assert sr.parse_rulings("A charter that mentions rulings in passing.") == []
+    assert sr.parse_rulings("") == []
+    assert sr.parse_rulings(None) == []
+
+
+def test_the_section_ends_where_a_paragraph_starts():
+    text = "Rulings\n- Kept. (Operator)\n\nNotes written after the section.\n- Not a ruling.\n"
+    assert sr.parse_rulings(text) == ["Kept. (Operator)"]
+
+
+# ── the paths a command names ────────────────────────────────────────────
+
+
+ROOT = "/home/me/repo"
+
+
+@pytest.mark.parametrize("command,cwd,expected", [
+    ("sed -n 1,80p src/app/downloads.py", ROOT, ["src/app/downloads.py"]),
+    # Absolute inside the root, and outside it.
+    (f"cat {ROOT}/src/app/x.py /etc/hosts", ROOT, ["src/app/x.py"]),
+    # A command run from a subdirectory names paths relative to it.
+    ("grep -n retry downloads.py", f"{ROOT}/src/app", ["src/app/downloads.py"]),
+    ("cat ../../../elsewhere/x.py", f"{ROOT}/src", []),
+    # Flags, URLs and globs are not paths; a `--flag=path` and a `path:line` are.
+    ("pytest -q --rootdir=tests/unit tests/test_x.py::test_y", ROOT,
+     ["tests/unit", "tests/test_x.py"]),
+    ("curl https://example.com/a/b.json", ROOT, []),
+    ("ls src/*.py", ROOT, []),
+    ("vim src/app/x.py:120", ROOT, ["src/app/x.py"]),
+    # Repeats collapse; a bare word with no slash or extension is not a path.
+    ("git add src/a.py src/a.py && git commit -m done", ROOT, ["src/a.py"]),
+])
+def test_command_paths(command, cwd, expected):
+    assert sr.command_paths(command, root=ROOT, cwd=cwd) == expected
+
+
+def test_without_a_root_relative_paths_are_taken_as_given_and_absolute_ones_dropped():
+    assert sr.command_paths("cat src/a.py /abs/b.py") == ["src/a.py"]
+
+
+def test_an_unbalanced_quote_still_yields_paths():
+    assert sr.command_paths("echo 'oops src/a.py") == ["src/a.py"]
+
+
+# ── the arm ──────────────────────────────────────────────────────────────
+
+
+async def _arm(systems, paths, seen=None):
+    lister = AsyncMock(return_value=systems)
+    recorder = MagicMock()
+    with patch.object(sr.systems_svc, "list_systems", lister), \
+         patch.object(sr, "record_system_surfaced", recorder):
+        out = await real_rulings_for_paths(1, 2, paths, seen=seen, source="rulings_test")
+    return out, recorder
+
+
+@pytest.mark.asyncio
+async def test_a_touched_area_with_rulings_shows_them_once_in_full_and_records_it():
+    downloads = _system(104, "Download lifecycle", DOWNLOADS, ["src/app/downloads"])
+    out, recorder = await _arm([downloads], ["src/app/downloads/retry.py"])
+    [line] = out["lines"]
+    assert line.startswith("> Rulings for `src/app/downloads/retry.py`")
+    assert "Download lifecycle (System 104)" in line
+    assert "(1) Failed work is retried until it succeeds" in line
+    assert "(2) A blocklisted release falls off" in line
+    assert out["system_ids"] == [104]
+    recorder.assert_called_once()
+    assert recorder.call_args.kwargs["system_ids"] == [104]
+    assert recorder.call_args.kwargs["source"] == "rulings_test"
+
+
+@pytest.mark.asyncio
+async def test_an_area_without_rulings_says_nothing():
+    plain = _system(5, "Billing", "What billing is for, and nothing decided.", ["src/billing"])
+    out, recorder = await _arm([plain], ["src/billing/invoice.py"])
+    assert out == {"lines": [], "system_ids": []}
+    recorder.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_an_area_without_patterns_claims_no_files():
+    unnamed = _system(104, "Download lifecycle", DOWNLOADS, [])
+    out, _ = await _arm([unnamed], ["src/app/downloads/retry.py"])
+    assert out["lines"] == []
+
+
+@pytest.mark.asyncio
+async def test_a_path_in_two_areas_hears_both():
+    downloads = _system(104, "Download lifecycle", DOWNLOADS, ["src/app/downloads"])
+    storage = _system(7, "Storage", "Where files go.\n\nRulings\n- Never delete a user file. (Operator)\n",
+                      ["src/app/**/*.py"])
+    out, _ = await _arm([downloads, storage], ["src/app/downloads/retry.py"])
+    assert len(out["lines"]) == 2
+    assert out["system_ids"] == [104, 7]
+
+
+@pytest.mark.asyncio
+async def test_a_repeat_is_a_reference_and_is_not_counted_again():
+    downloads = _system(104, "Download lifecycle", DOWNLOADS, ["src/app/downloads"])
+    out, recorder = await _arm([downloads], ["src/app/downloads/retry.py"], seen=[104])
+    [line] = out["lines"]
+    assert "shown earlier this session" in line
+    assert "Failed work is retried" not in line
+    assert out["system_ids"] == []
+    recorder.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_no_project_or_no_paths_reads_nothing():
+    lister = AsyncMock(return_value=[])
+    with patch.object(sr.systems_svc, "list_systems", lister):
+        assert await real_rulings_for_paths(1, 0, ["src/a.py"], source="t") == {"lines": [], "system_ids": []}
+        assert await real_rulings_for_paths(1, 2, [], source="t") == {"lines": [], "system_ids": []}
+    lister.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_a_failing_lookup_fails_open():
+    with patch.object(sr.systems_svc, "list_systems", AsyncMock(side_effect=RuntimeError("db"))):
+        out = await real_rulings_for_paths(1, 2, ["src/a.py"], source="t")
+    assert out == {"lines": [], "system_ids": []}
+
+
+@pytest.mark.asyncio
+async def test_a_long_list_is_bounded_per_area():
+    many = "Rulings\n" + "".join(f"- Ruling {i}. (Operator)\n" for i in range(12))
+    area = _system(9, "Busy", many, ["src"])
+    out, _ = await _arm([area], ["src/x.py"])
+    assert "(8) Ruling 7." in out["lines"][0]
+    assert "Ruling 8." not in out["lines"][0]
+    assert "+4 more in `get_system(9)`" in out["lines"][0]
+
+
+# ── the wiring ───────────────────────────────────────────────────────────
+
+
+RULING_LINE = "> Rulings for `src/a.py` — the operator's decisions about A (System 3): (1) x"
+
+
+@pytest.mark.asyncio
+async def test_the_tool_arm_leads_with_rulings_and_hands_back_what_it_showed():
+    rulings = AsyncMock(return_value={"lines": [RULING_LINE], "system_ids": [3]})
+    with patch.object(pc, "_tool_rule_hint", AsyncMock(return_value={
+            "context": "> a rule line", "rule_ids": [8], "checkpoint": {}})), \
+         patch.object(pc, "get_writepath_config", AsyncMock(return_value=writepath_cfg())), \
+         patch.object(pc.system_rulings_svc, "rulings_for_paths", rulings):
+        out = await pc.build_tool_rule_hint(
+            1, "Bash", f"cat {ROOT}/src/a.py", project_id=2,
+            root=ROOT, cwd=ROOT, seen_ruling_systems=[5],
+        )
+    assert out["context"].splitlines() == [RULING_LINE, "> a rule line"]
+    assert out["ruling_system_ids"] == [3]
+    args, kwargs = rulings.call_args
+    assert args[2] == ["src/a.py"]
+    assert kwargs["seen"] == [5] and kwargs["source"] == "rulings_pre_tool"
+
+
+@pytest.mark.asyncio
+async def test_the_tool_arm_adds_no_key_when_no_ruling_was_shown():
+    with patch.object(pc, "_tool_rule_hint", AsyncMock(return_value={
+            "context": "", "rule_ids": [], "checkpoint": {}})), \
+         patch.object(pc, "get_writepath_config", AsyncMock(return_value=writepath_cfg())):
+        out = await pc.build_tool_rule_hint(1, "Bash", "ls", project_id=2)
+    assert "ruling_system_ids" not in out
+
+
+@pytest.mark.asyncio
+async def test_a_write_with_no_prior_art_still_carries_its_areas_rulings():
+    rulings = AsyncMock(return_value={"lines": [RULING_LINE], "system_ids": [3]})
+    with patch.object(pc, "get_writepath_config", AsyncMock(return_value=writepath_cfg())), \
+         patch.object(pc.snippets_svc, "list_snippets", AsyncMock(return_value=([], 0))), \
+         patch.object(pc, "semantic_search_notes", AsyncMock(return_value=[])), \
+         patch.object(pc, "record_retrieval", MagicMock()), \
+         patch.object(pc.projects_svc, "get_project", AsyncMock(return_value=None)), \
+         patch.object(pc.system_rulings_svc, "rulings_for_paths", rulings):
+        out = await pc.build_write_path_hint(
+            1, "src/a.py", code="x = 1", project_id=2, seen_ruling_systems=[9],
+        )
+    assert out["context"] == RULING_LINE
+    assert out["ruling_system_ids"] == [3]
+    args, kwargs = rulings.call_args
+    assert args[2] == ["src/a.py"]
+    assert kwargs["seen"] == [9] and kwargs["source"] == "rulings_write_path"
diff --git a/tests/test_write_path_trigger.py b/tests/test_write_path_trigger.py
index 8800f5f..14ce8ab 100644
--- a/tests/test_write_path_trigger.py
+++ b/tests/test_write_path_trigger.py
@@ -970,7 +970,7 @@ def test_route_reads_every_arg_the_hook_sends():
         routes._project_scope
     )
     for arg in ("path", "code", "repo", "project_id", "exclude_ids",
-                "exclude_sync_ids", "shapes"):
+                "exclude_sync_ids", "shapes", "seen_ruling_systems"):
         assert f'request.args.get("{arg}"' in src, f"route ignores {arg}"
 
     hook = HOOK.read_text()
@@ -991,6 +991,9 @@ def test_route_reads_every_arg_the_hook_sends():
     assert "printf '&held_rule_ids=" in defs, (
         "the opened ledger's query key is no longer spelled in the helper"
     )
+    # The rulings ledger (milestone 444), shared with the tool-rules hook.
+    assert "scribe_rulings_query" in hook, "hook no longer sends the rulings ledger"
+    assert "printf '&seen_ruling_systems=" in defs
 
 
 def test_route_resolves_repo_to_a_project_not_to_a_location_filter():