feat(lessons): both records show the link in the web UI (milestone 440 step 7, #4635)

The lesson page gains an "Instance of" panel that holds one of three answers.
Unjudged is the fall-through, so it is stated rather than left blank:
- the rule(s) it was judged an instance of;
- "No rule — <why>";
- "Not yet judged".

Suggested links show what they rest on (distinct situations, and projects
when more than one), with Confirm / Not an instance for a reader who can
write. Rejected links stay listed with their reason.

The rule slide-over lists the lessons that are instances of it, plus the
suggestions waiting on a judgment. Each entry links through to the other
record, and kind and state wear the existing .rule-chip.

The write check moves to utils/permission.ts. The copy on the snippet page
looked for "edit", which the server never sends, so shared editors saw a
read-only page (#4640 "The snippet page hid its edit controls from shared
editors"). Guards pin the client's unions and write levels to the
service's, the model's and access.py's own values.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/api/lessons.ts

@@ -1,6 +1,34 @@
 import type { RecordUsage } from "@/types/usage";
 
-import { apiGet, apiPost, apiPatch, apiDelete } from "@/api/client";
+import { apiGet, apiPost, apiPut, apiPatch, apiDelete } from "@/api/client";
+import type { RuleKind } from "@/api/rulebooks";
+
+/** Where a lesson stands on "which rule is this an instance of?"
+ *  (`services/lesson_rules.py`: LINKED / NO_RULE / UNJUDGED). Three answers,
+ *  not two: "looked at and found to stand alone" and "nobody has looked" are
+ *  different facts, and the second is the one worth acting on. A rejected link
+ *  alone leaves a lesson unjudged — "not that rule" does not say whether
+ *  another one fits. */
+export type RuleJudgment = "linked" | "no_rule" | "unjudged";
+
+/** A link's state (`models/lesson_rule_link.py` LINK_STATES). */
+export type LinkState = "suggested" | "confirmed" | "rejected";
+
+/** One link from a lesson to a rule, in the reader's view: only rules the
+ *  reader owns are listed (`rules_for_lessons`). */
+export interface LessonRuleLink {
+  id: number;
+  title: string;
+  kind: RuleKind;
+  /** `suggested` carries nothing in retrieval until it is judged; only
+   *  `confirmed` changes what surfaces; `rejected` is kept so the pair is
+   *  never proposed again. */
+  state: LinkState;
+  /** Why it was confirmed or rejected. */
+  note: string;
+  /** What a suggestion rests on — sent on suggested links only. */
+  evidence?: { situations: number; projects: number; co_surfaced: number };
+}
 
 /** A lesson: a transferable insight, retrievable by the SITUATION it applies
  *  to rather than by its topic.
@@ -51,6 +79,13 @@ export interface Lesson {
   updated_at: string | null;
   systems?: { id: number; name: string }[];
   usage?: RecordUsage;
+  /** The rules this lesson points at, confirmed first, then suggested, then
+   *  rejected. Absent (with `rule_judgment`) when the links could not be read
+   *  — which is "not attached", never "no rule". */
+  rules?: LessonRuleLink[];
+  rule_judgment?: RuleJudgment;
+  /** The "no rule fits" answer, present when that is the judgment. */
+  no_rule?: { why: string; judged_at: string | null };
   /** Set when another user owns this record. */
   shared?: boolean;
   owner?: string | null;
@@ -128,6 +163,17 @@ export function updateLesson(
   return apiPatch<Lesson>(`/api/lessons/${id}`, payload);
 }
 
+/** Confirm or reject one lesson→rule link. Confirming also clears a "no rule
+ *  fits" answer: the two cannot both be the current answer. */
+export function judgeLessonLink(
+  lessonId: number,
+  ruleId: number,
+  verdict: "confirm" | "reject",
+  note = "",
+): Promise<unknown> {
+  return apiPut(`/api/lessons/${lessonId}/rules/${ruleId}`, { verdict, note });
+}
+
 /** Trash, not erase — recoverable. `apiDelete` discards the body, which is the
  *  established shape here (snippets delete the same way): the batch id is in
  *  the response, but no caller has needed it and inventing a second delete

frontend/src/api/rulebooks.ts

@@ -1,6 +1,7 @@
 import type { RecordUsage } from "@/types/usage";
 
 import { apiGet, apiPost, apiPatch, apiDelete } from "@/api/client";
+import type { LinkState } from "@/api/lessons";
 
 /** How a rule reaches a session (milestone 307). */
 
@@ -82,6 +83,10 @@ export interface Rule {
   /** Present only when the rule has them (the server omits empty keys). */
   systems?: { id: number; name: string }[];
   relations?: RuleRelation[];
+  /** The lessons that point at this rule (milestone 440) — the concrete
+   *  situations judged instances of it, plus any suggested and awaiting a
+   *  judgment. Readable lessons only; omitted when there are none. */
+  lessons?: { id: number; title: string; state: LinkState; note: string }[];
 }
 
 /**

frontend/src/components/rules/RuleEditorSlideOver.vue

@@ -27,6 +27,14 @@ const expiresWhen = ref("");
 
 const relations = computed(() => store.currentRule?.relations ?? []);
 
+// The lessons that point at this rule (milestone 440): confirmed instances
+// first, then suggestions waiting on a judgment. A rejected lesson does not
+// point at the rule, so it is not listed here — it stays readable on the
+// lesson, where the judgment was made.
+const lessons = computed(() =>
+  (store.currentRule?.lessons ?? []).filter((l) => l.state !== "rejected"),
+);
+
 // The label a reader needs to judge an edge, not the stored token.
 const RELATION_LABEL: Record<string, { outgoing: string; incoming: string }> = {
   co_surfaces: { outgoing: "arrives with", incoming: "arrives with" },
@@ -279,6 +287,21 @@ watch(() => props.ruleId, load);
         </p>
       </section>
 
+      <section v-if="lessons.length" class="relations">
+        <h3>Lessons that are instances of it</h3>
+        <ul>
+          <li v-for="l in lessons" :key="l.id" class="relation">
+            <router-link :to="`/lessons/${l.id}`" class="relation-target">{{ l.title }}</router-link>
+            <span v-if="l.state === 'suggested'" class="rule-chip">suggested</span>
+            <span v-if="l.note" class="relation-note">{{ l.note }}</span>
+          </li>
+        </ul>
+        <p class="field-note">
+          The situations that keep proving this rule. A confirmed lesson brings the rule along
+          when it surfaces; a suggested one waits for a judgment on the lesson's page.
+        </p>
+      </section>
+
       <label>
         Why
         <textarea v-model="why" rows="4" placeholder="Rationale — the reason this rule exists." />
@@ -394,3 +417,8 @@ legend { padding: 0 0.35rem; font-size: 0.8rem; color: var(--fs-text-tertiary);
 .trash, .close { background: none; border: none; cursor: pointer; opacity: 0.6; font-size: 1.25em; }
 .trash:hover, .close:hover { opacity: 1; }
 </style>
+
+<!-- `.rule-chip` for the "suggested" marker on a lesson — the chip the rule
+     panes already use, loaded here because the slide-over can open with no
+     pane that loads it (a link straight to ?rule=N). -->
+<style src="@/assets/rules-shared.css" />

frontend/src/utils/permission.ts

@@ -0,0 +1,12 @@
+/** Whether the reader may change a record, from the `permission` its read
+ *  carried. The levels are services/access.py's PERMISSION_RANK — viewer,
+ *  editor, admin, owner — and absent means the reader owns it: the server
+ *  labels a record only when it reached the reader through a share. This only
+ *  decides which controls a page shows; the server enforces the write. Kept in
+ *  one place so every page agrees, with each other and with the server, about
+ *  who can edit. */
+export const WRITE_LEVELS: readonly string[] = ["editor", "admin", "owner"];
+
+export function canWriteRecord(permission: string | undefined): boolean {
+  return permission === undefined || WRITE_LEVELS.includes(permission);
+}

frontend/src/views/LessonDetailView.vue

@@ -16,18 +16,31 @@
  * difference between this kind and a rule, and it is the reason the kind
  * exists (#3727) — sessions were proposing rules for things that should never
  * have bound anyone.
+ *
+ * BUT IT CAN POINT AT ONE (milestone 440). A lesson that is an instance of a
+ * rule says so, and the page shows which of the three answers it holds: the
+ * rule(s) it was judged an instance of, "no rule fits" with the reason, or
+ * not yet judged. The third is the one worth acting on, so it is stated as
+ * plainly as the other two rather than left as an empty panel.
  */
 import { computed, onMounted, ref, watch } from "vue";
 import { useRoute, useRouter } from "vue-router";
 
 import { apiErrorMessage } from "@/api/client";
-import { deleteLesson, getLesson, type Lesson } from "@/api/lessons";
+import {
+  deleteLesson,
+  getLesson,
+  judgeLessonLink,
+  type Lesson,
+  type LessonRuleLink,
+} from "@/api/lessons";
 import ConfirmDialog from "@/components/ConfirmDialog.vue";
 import TagPill from "@/components/TagPill.vue";
 import UsageBadge from "@/components/UsageBadge.vue";
 import { DEAD_WEIGHT_ADVICE } from "@/utils/deadWeight";
 import { useToastStore } from "@/stores/toast";
 import { renderMarkdown } from "@/utils/markdown";
+import { canWriteRecord } from "@/utils/permission";
 
 const route = useRoute();
 const router = useRouter();
@@ -55,6 +68,53 @@ function sourceHref(rec: { id: number; is_task?: boolean; note_type?: string })
   return `/notes/${rec.id}`;
 }
 
+const canWrite = computed(() => canWriteRecord(lesson.value?.permission));
+
+/** The links by state — each state reads differently. Confirmed links are
+ *  the answer; suggested ones are evidence waiting on a judgment; rejected
+ *  ones are kept so the pair is never proposed again, and shown so the reason
+ *  stays readable. */
+const linksIn = (state: LessonRuleLink["state"]) =>
+  computed(() => (lesson.value?.rules ?? []).filter((r) => r.state === state));
+const confirmedRules = linksIn("confirmed");
+const suggestedRules = linksIn("suggested");
+const rejectedRules = linksIn("rejected");
+
+/** A rule opens in the rules view's editor, which takes the rule alone. */
+function ruleHref(ruleId: number) {
+  return { path: "/rules", query: { rule: String(ruleId) } };
+}
+
+/** What a suggestion rests on, in the units it was proposed by: distinct
+ *  situations, not raw arrivals — one situation repeated proves nothing. */
+function evidenceLine(ev: NonNullable<LessonRuleLink["evidence"]>): string {
+  const situations = `${ev.situations} distinct situation${ev.situations === 1 ? "" : "s"}`;
+  const projects = ev.projects > 1 ? `, across ${ev.projects} projects` : "";
+  return `Arrived together in ${situations}${projects}.`;
+}
+
+const judging = ref<number | null>(null);
+
+/** Judge a suggested link from here. Re-reads the lesson rather than editing
+ *  the list in place: confirming also clears a "no rule fits" answer, and the
+ *  judgment line has to come back from the server to be right. */
+async function judge(rule: LessonRuleLink, verdict: "confirm" | "reject") {
+  judging.value = rule.id;
+  try {
+    await judgeLessonLink(lessonId.value, rule.id, verdict);
+    lesson.value = await getLesson(lessonId.value);
+    toast.show(
+      verdict === "confirm"
+        ? "Linked — the rule can now surface through this lesson"
+        : "Not an instance — this pair will not be suggested again",
+    );
+  } catch (e) {
+    toast.show(apiErrorMessage(e, "Failed to record the judgment"), "error");
+  } finally {
+    judging.value = null;
+  }
+}
+
 async function load() {
   loading.value = true;
   error.value = null;
@@ -141,6 +201,80 @@ onMounted(load);
         </ul>
       </section>
 
+      <!-- Which rule this is an instance of. Absent when the links could not
+           be read: that is "not attached", never "no rule". -->
+      <section v-if="lesson.rule_judgment" class="ld-panel">
+        <h2 class="ld-panel-label">Instance of</h2>
+
+        <template v-if="lesson.rule_judgment === 'linked'">
+          <ul v-if="confirmedRules.length" class="ld-sources">
+            <li v-for="r in confirmedRules" :key="r.id">
+              <router-link :to="ruleHref(r.id)" class="ld-link">
+                {{ r.title }}
+              </router-link>
+              <span v-if="r.kind === 'preference'" class="rule-chip rule-chip-preference">
+                preference
+              </span>
+              <p v-if="r.note" class="ld-link-note">{{ r.note }}</p>
+            </li>
+          </ul>
+          <!-- Judged by its owner against a rule this reader cannot open. -->
+          <p v-else class="ld-muted">Linked to a rule that is not shared with you.</p>
+        </template>
+        <p v-else-if="lesson.rule_judgment === 'no_rule'" class="ld-judgment">
+          No rule — {{ lesson.no_rule?.why }}
+        </p>
+        <p v-else class="ld-muted ld-empty">
+          Not yet judged — no rule has been named for this situation, and
+          nobody has said none fits.
+        </p>
+
+        <template v-if="suggestedRules.length">
+          <h3 class="ld-sub-label">Suggested</h3>
+          <ul class="ld-sources">
+            <li v-for="r in suggestedRules" :key="r.id">
+              <router-link :to="ruleHref(r.id)" class="ld-link">
+                {{ r.title }}
+              </router-link>
+              <span v-if="r.kind === 'preference'" class="rule-chip rule-chip-preference">
+                preference
+              </span>
+              <p v-if="r.evidence" class="ld-link-note">{{ evidenceLine(r.evidence) }}</p>
+              <div v-if="canWrite" class="ld-judge">
+                <button
+                  type="button"
+                  class="ld-ghost ld-small"
+                  :disabled="judging === r.id"
+                  @click="judge(r, 'confirm')"
+                >
+                  Confirm
+                </button>
+                <button
+                  type="button"
+                  class="ld-ghost ld-small"
+                  :disabled="judging === r.id"
+                  @click="judge(r, 'reject')"
+                >
+                  Not an instance
+                </button>
+              </div>
+            </li>
+          </ul>
+        </template>
+
+        <template v-if="rejectedRules.length">
+          <h3 class="ld-sub-label">Judged not an instance</h3>
+          <ul class="ld-sources ld-rejected">
+            <li v-for="r in rejectedRules" :key="r.id">
+              <router-link :to="ruleHref(r.id)" class="ld-link">
+                {{ r.title }}
+              </router-link>
+              <p v-if="r.note" class="ld-link-note">{{ r.note }}</p>
+            </li>
+          </ul>
+        </template>
+      </section>
+
       <section v-if="lesson.tags?.length" class="ld-tags">
         <TagPill v-for="t in lesson.tags" :key="t" :tag="t" />
       </section>
@@ -263,6 +397,24 @@ onMounted(load);
   font-size: 0.78rem;
 }
 
+.ld-link-note {
+  margin: var(--fs-space-1) 0 0;
+  color: var(--fs-text-secondary);
+  font-size: var(--fs-size-label);
+  line-height: 1.45;
+}
+.ld-judgment { margin: 0; font-size: 0.9rem; line-height: 1.5; }
+.ld-sub-label {
+  margin: var(--fs-space-3) 0 var(--fs-space-1);
+  font-size: var(--fs-size-label);
+  font-weight: var(--fs-weight-medium);
+  color: var(--fs-text-tertiary);
+}
+.ld-rejected .ld-link { color: var(--fs-text-secondary); }
+.ld-judge { display: flex; gap: var(--fs-space-2); margin-top: var(--fs-space-1); }
+.ld-small { padding: 0.15rem 0.6rem; font-size: var(--fs-size-label); }
+.ld-ghost:disabled { opacity: var(--fs-disabled-opacity); cursor: default; }
+
 .ld-tags { display: flex; flex-wrap: wrap; gap: 0.35rem; margin-top: 1.25rem; }
 
 .ld-origin {
@@ -307,3 +459,7 @@ onMounted(load);
   font-size: 0.88rem;
 }
 </style>
+
+<!-- `.rule-chip` and its preference variant: the marker a rule's kind wears
+     everywhere else, reused rather than re-spelled. -->
+<style src="@/assets/rules-shared.css" />

frontend/src/views/SnippetDetailView.vue

@@ -10,6 +10,7 @@ import {
 import { useToastStore } from "@/stores/toast";
 import ConfirmDialog from "@/components/ConfirmDialog.vue";
 import { renderMarkdown } from "@/utils/markdown";
+import { canWriteRecord } from "@/utils/permission";
 
 const route = useRoute();
 const router = useRouter();
@@ -22,10 +23,7 @@ const showDeleteConfirm = ref(false);
 
 const id = computed(() => Number(route.params.id));
 
-const canWrite = computed(() => {
-  const p = snippet.value?.permission;
-  return p === undefined || p === "owner" || p === "edit" || p === "admin";
-});
+const canWrite = computed(() => canWriteRecord(snippet.value?.permission));
 
 const locations = computed(() => snippet.value?.snippet.locations ?? []);
 

tests/test_lesson_rule_link_ui.py

@@ -0,0 +1,117 @@
+"""Both records show the lesson → rule link in the web UI (milestone 440, #4635).
+
+The frontend has no component test runner, so these read the source — and
+each is written against something the backend owns, so a drift on either
+side fails here rather than rendering a page that quietly reads wrong:
+
+- the client's judgment and link-state unions are the service's and the
+  model's own values, so a renamed state cannot leave a branch that never
+  matches;
+- the lesson page branches on every judgment, with the unjudged answer as
+  the fall-through, so "not yet judged" is stated rather than left blank;
+- the write-level list the pages hide controls by is the server's
+  PERMISSION_RANK from editor up, which is the drift that had the snippet
+  page hiding its edit controls from shared editors (`"edit"` is not a level
+  the server sends).
+"""
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+from scribe.models.lesson_rule_link import LINK_STATES
+from scribe.services import lesson_rules as links_svc
+from scribe.services.access import PERMISSION_RANK
+
+FRONTEND = Path(__file__).resolve().parents[1] / "frontend" / "src"
+
+
+def _read(rel: str) -> str:
+    return (FRONTEND / rel).read_text()
+
+
+def _union(source: str, name: str) -> set[str]:
+    """The string members of `export type <name> = "a" | "b" …;`."""
+    m = re.search(rf"export type {name}\s*=\s*([^;]+);", source)
+    assert m, f"type {name} not found"
+    return set(re.findall(r'"([^"]+)"', m.group(1)))
+
+
+def _template(view: str) -> str:
+    return view[view.index("<template>"):view.rindex("</template>")]
+
+
+def test_the_client_judgment_union_is_the_services_three_answers():
+    assert _union(_read("api/lessons.ts"), "RuleJudgment") == {
+        links_svc.LINKED, links_svc.NO_RULE, links_svc.UNJUDGED,
+    }
+
+
+def test_the_client_link_states_are_the_models():
+    assert _union(_read("api/lessons.ts"), "LinkState") == set(LINK_STATES)
+
+
+def test_the_lesson_page_answers_all_three_judgments():
+    """`linked` and `no_rule` are tested by name; `unjudged` is the v-else
+    that closes the same chain, so a fourth state the server might add reads
+    as unjudged rather than as nothing."""
+    tpl = _template(_read("views/LessonDetailView.vue"))
+    linked = tpl.index(f"lesson.rule_judgment === '{links_svc.LINKED}'")
+    no_rule = tpl.index(f"lesson.rule_judgment === '{links_svc.NO_RULE}'")
+    assert linked < no_rule
+    after = tpl[no_rule:]
+    # The no-rule answer renders its reason, and the chain closes on a v-else.
+    para_end = after.index("</p>")
+    assert "lesson.no_rule?.why" in after[:para_end]
+    closing = after[para_end + len("</p>"):]
+    assert re.match(r"\s*<p v-else\b", closing), "the unjudged branch is not the chain's v-else"
+    assert "Not yet judged" in closing[:closing.index("</p>")]
+
+
+def test_the_panel_is_gated_on_the_judgment_being_attached():
+    """An absent `rule_judgment` is "the links could not be read" — never
+    "no rule" — so the panel must not render a state for it."""
+    tpl = _template(_read("views/LessonDetailView.vue"))
+    assert '<section v-if="lesson.rule_judgment"' in tpl
+
+
+def test_both_pages_link_through_to_the_other_record():
+    lesson_tpl = _read("views/LessonDetailView.vue")
+    assert re.search(r'path:\s*"/rules",\s*query:\s*\{\s*rule:', lesson_tpl)
+    rule_tpl = _template(_read("components/rules/RuleEditorSlideOver.vue"))
+    assert ':to="`/lessons/${l.id}`"' in rule_tpl
+
+
+def test_the_kind_and_state_markers_reuse_rule_chip():
+    """No new chip style where `.rule-chip` serves: both components load the
+    shared sheet and neither re-declares the class in its own block."""
+    for rel in ("views/LessonDetailView.vue", "components/rules/RuleEditorSlideOver.vue"):
+        src = _read(rel)
+        assert 'class="rule-chip' in _template(src), rel
+        assert '<style src="@/assets/rules-shared.css" />' in src, rel
+        scoped = src[src.index("<style scoped>"):]
+        scoped = scoped[:scoped.index("</style>")]
+        assert ".rule-chip" not in scoped, f"{rel} re-spells the chip"
+
+
+def test_the_write_levels_are_the_servers():
+    src = _read("utils/permission.ts")
+    m = re.search(r"WRITE_LEVELS[^=]*=\s*\[([^\]]*)\]", src)
+    assert m, "WRITE_LEVELS not found"
+    client = set(re.findall(r'"([^"]+)"', m.group(1)))
+    server = {p for p, rank in PERMISSION_RANK.items() if rank >= PERMISSION_RANK["editor"]}
+    assert client == server
+
+
+def test_no_page_spells_its_own_write_check():
+    """The helper exists so pages agree; a page comparing against a share
+    level by hand is the copy that drifted to `"edit"`. Matched on the names
+    only a share level uses — `admin` and `owner` are also user roles, and
+    `role === "admin"` is not this."""
+    offenders = [
+        str(p.relative_to(FRONTEND))
+        for p in [*FRONTEND.rglob("*.vue"), *FRONTEND.rglob("*.ts")]
+        if p != FRONTEND / "utils" / "permission.ts"
+        and re.search(r'[!=]==\s*"(?:viewer|editor|edit)"', p.read_text())
+    ]
+    assert offenders == []