diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 3a4d0ac4a..4eb540485 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -852,7 +852,10 @@ new table needed. `lineageweave/knowledge_graph.py`'s
 `backend/app/post_summary_ingestion.py`'s `persist_post_summary` now
 resolves each R&R actor's identity, stores that id on
 `post_summary_role` (ADR 0019 — `entity_name` is not unique), and calls
-the same `persist_edges_for_post` Keyman ingestion already uses. A person R&R
+the same `persist_edges_for_post` Keyman ingestion already uses.
+`resolve_corporate_entity` returns no id when two catalog rows share
+the top similarity score (ADR 0021), so the popup keeps that name as
+text instead of walking a homonym. A person R&R
 actor is opportunistically joined to an existing `cataloged_person` row
 by name (never originated by R&R itself -- documented gap in the ADR:
 `cataloged_person` needs `person_side_code`, which R&R's prompt does
diff --git a/CHANGELOG.d/0.86.4-tied-organization-similarity.md b/CHANGELOG.d/0.86.4-tied-organization-similarity.md
new file mode 100644
index 000000000..c6f1d8ef9
--- /dev/null
+++ b/CHANGELOG.d/0.86.4-tied-organization-similarity.md
@@ -0,0 +1,3 @@
+An R&R organization name that matches two catalog rows at the same
+similarity score stays text. Open the post after the catalog collision
+is unique, then click.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d30ae14aa..a6f73d113 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,15 @@ All notable changes to this project are documented here. Format follows
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); versioning follows
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.86.4] - 2026-08-16
+
+### Fixed
+
+- An R&R organization name that matches two catalog rows at the same
+  similarity score stays text (ADR 0021). Open the post — there is no
+  button until the catalog collision is unique. A unique exact match
+  among other same-named neighbors still walks the resolved org.
+
 ## [0.86.2] - 2026-08-16
 
 ### Fixed
diff --git a/CLAUDE.md b/CLAUDE.md
index c5a1828f2..704b82df1 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -21,3 +21,6 @@ Opening a cutoff title shows the live post -- compare it with the
 cutoff before treating the body as reconstructed evidence (ADR 0016).
 `POST /api/analysis-runs` records Pending on an authorized
 cutoff capture (ADR 0017) and does not reconstruct lineage.
+Two catalog orgs that share a display name and the same similarity
+score stay unbound (ADR 0021). Open the post — that name is text
+until a unique catalog id is stored.
diff --git a/docs/adr/0010-corporate-hierarchy-auto-creation.md b/docs/adr/0010-corporate-hierarchy-auto-creation.md
index d034fe9b2..08796d183 100644
--- a/docs/adr/0010-corporate-hierarchy-auto-creation.md
+++ b/docs/adr/0010-corporate-hierarchy-auto-creation.md
@@ -24,9 +24,10 @@ until a verified creation path exists.
 extends the existing resolution pipeline with a creation fallback, not
 a competing algorithm:
 
-1. Try `resolve_corporate_entity` (similarity matching, unchanged,
-   Bhattacharya & Getoor, 2007) first -- an already-cataloged entity
-   still resolves exactly as before.
+1. Try `resolve_corporate_entity` (similarity matching,
+   Bhattacharya & Getoor, 2007; tied top scores stay unbound, ADR
+   0021) first -- an already-cataloged entity still resolves exactly
+   as before when the top score is unique.
 2. On a miss, ask an LLM
    (`lineageweave.corporate_hierarchy_inference.CorporateHierarchyInferenceClient`)
    to propose this organization's place in the Group -> Company ->
@@ -91,10 +92,13 @@ reuse-the-verification-client pattern and
 [ADR 0009](0009-cross-post-actor-identity.md)'s cross-post identity
 work -- an R&R organization actor's identity is now genuinely resolved
 to a real corporate hierarchy node, not left as free text even when no
-prior mention of it existed anywhere in the dataset.
+prior mention of it existed anywhere in the dataset. A tied similarity
+score stays unbound ([ADR 0021](0021-tied-organization-similarity.md)).
 
 ## References (APA 7th)
 
 Bhattacharya, I., & Getoor, L. (2007). Collective entity resolution in relational data. *ACM Transactions on Knowledge Discovery from Data*, 1(1), Article 5. https://doi.org/10.1145/1217299.1217304
 
+Fellegi, I. P., & Sunter, A. B. (1969). A theory for record linkage. *Journal of the American Statistical Association, 64*(328), 1183–1210. https://doi.org/10.2307/2286061
+
 Miles, A., & Bechhofer, S. (Eds.). (2009). *SKOS simple knowledge organization system reference*. World Wide Web Consortium. https://www.w3.org/TR/skos-reference/
diff --git a/docs/adr/0019-role-catalog-identity.md b/docs/adr/0019-role-catalog-identity.md
index 32b5d0a09..923a0001d 100644
--- a/docs/adr/0019-role-catalog-identity.md
+++ b/docs/adr/0019-role-catalog-identity.md
@@ -40,8 +40,9 @@ Two same-named mentions stay unbound rather than guessing.
 ## Consequences
 
 - Open a post whose R&R names an organization that shares a display
-  name with another catalog row. The button walks the resolved id, not
-  the homonym.
+  name with another catalog row. When persist stored a unique id, the
+  button walks that id, not the homonym. When write-time similarity
+  ties, the name stays text (ADR 0021).
 - Clicking that name still uses `GET /api/corporate-entities/{id}/related`
   or `GET /api/teams/{id}/related`. Authz stays person/entity-parity:
   a team mentioned only on another corp's private post is 403; an
diff --git a/docs/adr/0021-tied-organization-similarity.md b/docs/adr/0021-tied-organization-similarity.md
new file mode 100644
index 000000000..91311a8fa
--- /dev/null
+++ b/docs/adr/0021-tied-organization-similarity.md
@@ -0,0 +1,80 @@
+# ADR 0021 — Tied organization similarity stays unbound
+
+**Decision status:** Accepted
+**Date:** 2026-08-16
+
+## Context
+
+ADR 0019 stores the catalog id on `post_summary_role` so fetch no
+longer rejoins `corporate_entity.entity_name`. Persist still calls
+`resolve_corporate_entity` before that write. That function kept the
+first candidate whose similarity score was strictly greater than the
+running best. Two catalog rows can share a display name (different
+`corporate_entity_code`, different parents). Both score 1.0. The
+winner was then whichever row an unordered `select` happened to
+return.
+
+The buyer path is: open the post, click the R&R organization name,
+walk related nodes. A first-wins bind walks the homonym. ADR 0019's
+backfill already refuses to guess when two same-named mentions exist
+on one post (`HAVING count(*) = 1`). Write-time resolution did not.
+
+String similarity is only the candidate-generation stage of
+collective entity resolution (Bhattacharya & Getoor, 2007). Fellegi
+and Sunter (1969) leave an uncertain pair for clerical review rather
+than forcing a link. Christen (2012) treats that hold-out as part of
+the matching decision, not a defect to paper over.
+
+```mermaid
+flowchart TD
+    mention["R&R organization name"] --> score["Score every catalog row"]
+    score --> unique{"One unique top score at or above the threshold?"}
+    unique -->|yes| bind["Store that catalog id on the role row"]
+    unique -->|no| unbound["Leave the name as text — no related-node button"]
+    bind --> walk["Click walks GET /api/corporate-entities/{id}/related"]
+    unbound --> later["Resolve the catalog collision, then persist again"]
+```
+
+## Decision
+
+`resolve_corporate_entity` returns a catalog id only when exactly one
+candidate holds the top score and that score clears `min_similarity`.
+A tied top score returns `None`. `persist_post_summary` then stores
+no `cataloged_corporate_entity_id` and writes no
+`post_organization_mention`. The popup shows the name as text, not a
+button.
+
+The same function is shared with Keyman affiliation matching and
+entity-relationship counterparty resolution. Those paths already
+treat `None` as "do not invent a link."
+
+This does not create a `corporate_entity` row. Null inference /
+verification clients stay unavailable. Do not invent a TEPP theta.
+
+## Consequences
+
+- Open a post whose R&R names `Tied Energy` when two catalog rows
+  share that display name. The name is not a button. Resolve the
+  catalog collision (distinct codes, parents, or a verified unique
+  match), persist the summary again, then click.
+- A unique exact match among other homonym neighbors still binds.
+- The same catalog id listed twice in the candidate snapshot is one
+  winner, not a tie.
+
+## References
+
+Bhattacharya, I., & Getoor, L. (2007). Collective entity resolution
+in relational data. *ACM Transactions on Knowledge Discovery from
+Data, 1*(1), Article 5. https://doi.org/10.1145/1217299.1217304
+
+Christen, P. (2012). *Data matching: Concepts and techniques for
+record linkage, entity resolution, and duplicate detection*.
+Springer. https://doi.org/10.1007/978-3-642-31164-2
+
+Fellegi, I. P., & Sunter, A. B. (1969). A theory for record linkage.
+*Journal of the American Statistical Association, 64*(328),
+1183–1210. https://doi.org/10.2307/2286061
+
+International Organization for Standardization. (2023). *ISO/IEC
+11179-1:2023: Information technology—Metadata registries (MDR)—Part 1:
+Framework*.
diff --git a/docs/doctoring/RELATED_NODE_TEAM_ORG_REFERENCES.md b/docs/doctoring/RELATED_NODE_TEAM_ORG_REFERENCES.md
index fc7ded98f..9471d8446 100644
--- a/docs/doctoring/RELATED_NODE_TEAM_ORG_REFERENCES.md
+++ b/docs/doctoring/RELATED_NODE_TEAM_ORG_REFERENCES.md
@@ -29,3 +29,15 @@ https://doi.org/10.1007/978-1-4842-5540-7
 International Organization for Standardization. (2023). *ISO/IEC
 11179-1:2023: Information technology—Metadata registries (MDR)—Part 1:
 Framework*.
+
+Bhattacharya, I., & Getoor, L. (2007). Collective entity resolution
+in relational data. *ACM Transactions on Knowledge Discovery from
+Data, 1*(1), Article 5. https://doi.org/10.1145/1217299.1217304
+
+Christen, P. (2012). *Data matching: Concepts and techniques for
+record linkage, entity resolution, and duplicate detection*.
+Springer. https://doi.org/10.1007/978-3-642-31164-2
+
+Fellegi, I. P., & Sunter, A. B. (1969). A theory for record linkage.
+*Journal of the American Statistical Association, 64*(328),
+1183–1210. https://doi.org/10.2307/2286061
diff --git a/frontend/package.json b/frontend/package.json
index fb52f7948..05f877ba2 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "frontend",
   "private": true,
-  "version": "0.86.2",
+  "version": "0.86.4",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/lineageweave/__init__.py b/lineageweave/__init__.py
index efe84890b..93c53ac54 100644
--- a/lineageweave/__init__.py
+++ b/lineageweave/__init__.py
@@ -55,4 +55,4 @@
     "sentence_excerpts",
 ]
 
-__version__ = "0.86.2"
+__version__ = "0.86.4"
diff --git a/lineageweave/corporate_hierarchy_resolution.py b/lineageweave/corporate_hierarchy_resolution.py
index 1fa480cc3..30ce357fe 100644
--- a/lineageweave/corporate_hierarchy_resolution.py
+++ b/lineageweave/corporate_hierarchy_resolution.py
@@ -18,6 +18,8 @@
 upgrade path once real usage shows single-mention similarity scoring
 under- or over-resolving in practice -- it is not implemented here because
 nothing yet demonstrates the need for it over this simpler, cheaper stage.
+A tied top score therefore stays unbound (ADR 0021; Fellegi & Sunter,
+1969) instead of first-winning a homonym.
 """
 
 from __future__ import annotations
@@ -61,19 +63,21 @@ def resolve_corporate_entity(
     candidates: Sequence[CorporateEntityCandidate],
     min_similarity: float = DEFAULT_MIN_SIMILARITY,
 ) -> str | None:
-    """Returns the best-matching candidate's `corporate_entity_id`, or
-    `None` if no candidate clears `min_similarity`.
+    """Return the unique best-matching catalog id, or ``None``.
 
-    Returning `None` for a genuine non-match is the point, not a failure
-    case to work around: a wrong hierarchy link corrupts every downstream
-    Knowledge Graph traversal through it, so "no confident match" must
-    stay a real, distinguishable outcome from "matched entity X."
+    ``None`` is the honest outcome when no candidate clears
+    ``min_similarity`` **or** two or more candidates share the top
+    score. A wrong hierarchy link corrupts every downstream Knowledge
+    Graph walk, so a tied homonym must not become a button (ADR 0021;
+    Fellegi & Sunter, 1969; Bhattacharya & Getoor, 2007). Duplicate
+    rows for the same ``corporate_entity_id`` still count as one
+    candidate.
     """
     normalized_mention = normalize_organization_name(mentioned_name)
     if not normalized_mention:
         return None
 
-    best_id: str | None = None
+    best_ids: list[str] = []
     best_score = 0.0
     for candidate in candidates:
         score = SequenceMatcher(
@@ -81,6 +85,14 @@ def resolve_corporate_entity(
         ).ratio()
         if score > best_score:
             best_score = score
-            best_id = candidate.corporate_entity_id
+            best_ids = [candidate.corporate_entity_id]
+        elif (
+            score == best_score
+            and score > 0.0
+            and candidate.corporate_entity_id not in best_ids
+        ):
+            best_ids.append(candidate.corporate_entity_id)
 
-    return best_id if best_score >= min_similarity else None
+    if best_score < min_similarity or len(best_ids) != 1:
+        return None
+    return best_ids[0]
diff --git a/pyproject.toml b/pyproject.toml
index 6e41c7ca7..7254de99e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "lineageweave"
-version = "0.86.2"
+version = "0.86.4"
 description = "Reconstructs git-branch-style lineage DAGs from scattered short records using multi-channel score fusion and LLM adjudication."
 readme = "README.md"
 license = { text = "MIT" }
diff --git a/tests/test_corporate_hierarchy_resolution.py b/tests/test_corporate_hierarchy_resolution.py
index 218fd4e00..d59c081b4 100644
--- a/tests/test_corporate_hierarchy_resolution.py
+++ b/tests/test_corporate_hierarchy_resolution.py
@@ -60,6 +60,35 @@ def test_no_candidates_does_not_resolve() -> None:
     assert resolve_corporate_entity("Acme Electronics Korea", []) is None
 
 
+def test_tied_same_display_name_does_not_resolve() -> None:
+    """Two catalog orgs can share a display name. First-wins is a homonym."""
+    homonyms = [
+        CorporateEntityCandidate("mentioned-id", "Homonym Energy"),
+        CorporateEntityCandidate("other-id", "Homonym Energy"),
+    ]
+    assert resolve_corporate_entity("Homonym Energy", homonyms) is None
+
+
+def test_tied_same_display_name_ignores_duplicate_candidate_rows() -> None:
+    """The same catalog id listed twice is still one unique winner."""
+    duplicated = [
+        CorporateEntityCandidate("korea-id", "Acme Electronics Korea"),
+        CorporateEntityCandidate("korea-id", "Acme Electronics Korea"),
+    ]
+    assert resolve_corporate_entity("Acme Electronics Korea", duplicated) == "korea-id"
+
+
+def test_unique_exact_name_still_wins_among_homonym_neighbors() -> None:
+    """A unique exact match stays a button; only a tied top score fails closed."""
+    mixed = [
+        CorporateEntityCandidate("korea-id", "Acme Electronics Korea"),
+        CorporateEntityCandidate("homonym-a", "Homonym Energy"),
+        CorporateEntityCandidate("homonym-b", "Homonym Energy"),
+    ]
+    assert resolve_corporate_entity("Acme Electronics Korea", mixed) == "korea-id"
+    assert resolve_corporate_entity("Homonym Energy", mixed) is None
+
+
 def test_normalize_strips_suffix_punctuation_and_case() -> None:
     assert normalize_organization_name("Acme Electronics Korea, Ltd.") == "acme electronics korea"
     assert normalize_organization_name("  ACME   Group  ") == "acme group"
diff --git a/tests/test_ingestion_transaction_contracts.py b/tests/test_ingestion_transaction_contracts.py
index d2994e2c4..1de2da17e 100644
--- a/tests/test_ingestion_transaction_contracts.py
+++ b/tests/test_ingestion_transaction_contracts.py
@@ -507,3 +507,21 @@ def test_role_catalog_identity_is_stored_on_the_role_row() -> None:
     assert "cataloged_corporate_entity_id" in upgrade
     assert "0019_role_catalog_identity.sql" in dockerfile
     assert "ADR 0019" in changelog
+
+
+def test_tied_organization_similarity_fails_closed() -> None:
+    """ADR 0021: write-time resolution must not first-win a tied top score."""
+    root = Path(__file__).resolve().parents[1]
+    source = (root / "lineageweave" / "corporate_hierarchy_resolution.py").read_text(
+        encoding="utf-8"
+    )
+    changelog = (root / "CHANGELOG.md").read_text(encoding="utf-8")
+    adr = (root / "docs" / "adr" / "0021-tied-organization-similarity.md").read_text(
+        encoding="utf-8"
+    )
+    resolve_source = source.split("def resolve_corporate_entity", 1)[1]
+    assert "len(best_ids) != 1" in resolve_source
+    assert "score > best_score" in resolve_source
+    assert "ADR 0021" in changelog
+    assert "Tied organization similarity stays unbound" in adr
+    assert "Fellegi" in adr
diff --git a/tests/test_person_mention_projection.py b/tests/test_person_mention_projection.py
index 81e63a75f..14ae7efae 100644
--- a/tests/test_person_mention_projection.py
+++ b/tests/test_person_mention_projection.py
@@ -542,3 +542,59 @@ def test_homonym_organization_role_binds_the_resolved_catalog_id(
 
     database_dsn, post_id, _summary_person_id = projection_database.split("|")
     asyncio.run(_exercise_homonym_organization_role_binding(database_dsn, post_id))
+
+
+async def _exercise_tied_organization_similarity_stays_unbound(
+    database_dsn: str,
+    post_id: str,
+) -> None:
+    """Write-time resolution must not first-win a same-named catalog pair."""
+
+    connection = await asyncpg.connect(database_dsn)
+    try:
+        await connection.execute(
+            """
+            insert into corporate_entity
+                (corporate_entity_code, entity_name, entity_level_code)
+            values
+                ('HOMONYM-TIED-A', 'Tied Energy', 'company'),
+                ('HOMONYM-TIED-B', 'Tied Energy', 'company')
+            """
+        )
+        payload = await persist_post_summary(
+            connection,
+            post_id,
+            PostSummary(
+                korean_summary="동점 조직은 버튼을 만들지 않는다.",
+                roles_and_responsibilities=(
+                    RoleResponsibility(
+                        actor_name="Tied Energy",
+                        responsibility="납품 일정 확정",
+                        actor_type_code=ACTOR_TYPE_ORGANIZATION,
+                    ),
+                ),
+            ),
+        )
+        roles = payload["roles_and_responsibilities"]
+        assert len(roles) == 1
+        assert roles[0]["catalog_node_id"] is None
+        assert roles[0]["catalog_node_type_code"] is None
+        fetched = await fetch_persisted_summary(connection, post_id)
+        assert fetched is not None
+        assert fetched["roles_and_responsibilities"][0]["catalog_node_id"] is None
+        mention_count = await connection.fetchval(
+            "select count(*) from post_organization_mention where post_id = $1",
+            post_id,
+        )
+        assert mention_count == 0
+    finally:
+        await connection.close()
+
+
+def test_tied_organization_similarity_stays_unbound(
+    projection_database: str,
+) -> None:
+    """ADR 0021: open the post — the shared name is text, not a homonym button."""
+
+    database_dsn, post_id, _summary_person_id = projection_database.split("|")
+    asyncio.run(_exercise_tied_organization_similarity_stays_unbound(database_dsn, post_id))
diff --git a/uv.lock b/uv.lock
index e1d2860cf..0f0f81957 100644
--- a/uv.lock
+++ b/uv.lock
@@ -454,7 +454,7 @@ wheels = [
 
 [[package]]
 name = "lineageweave"
-version = "0.86.2"
+version = "0.86.4"
 source = { virtual = "." }
 dependencies = [
     { name = "certifi" },