diff --git a/docs/cmis-1-1-capability-scorecard.md b/docs/cmis-1-1-capability-scorecard.md
index 094941b..d7d29a2 100644
--- a/docs/cmis-1-1-capability-scorecard.md
+++ b/docs/cmis-1-1-capability-scorecard.md
@@ -13,6 +13,11 @@ The score below remains a product-depth estimate against mature CMIS products.
 The selected OpenCMIS baseline is now stable preparation evidence for
 repository/type and object/content services, not a full CMIS certification.
 
+Read-side contract update: `KONT-WP-0016` adds a documented bounded query
+subset, common CMIS `ORDER BY`, target/either relationship filters, enriched
+relationship and ACL projections, and explicit `notSupported` diagnostics for
+unsupported navigation selectors.
+
 Status: baseline scorecard for the current Browser Binding subset.
 
 ## Purpose
@@ -72,9 +77,9 @@ CMIS interoperability importance rather than engine-internal importance.
 | Metric | Score |
 | --- | ---: |
 | OpenCMIS selected-baseline infrastructure score | 99.1% |
-| Weighted CMIS 1.1 depth vs Hyland Alfresco benchmark | 60% |
-| Controlled-client Browser Binding usefulness | 82% |
-| Broad commodity CMIS client compatibility | 55% |
+| Weighted CMIS 1.1 depth vs Hyland Alfresco benchmark | 63% |
+| Controlled-client Browser Binding usefulness | 84% |
+| Broad commodity CMIS client compatibility | 57% |
 
 Interpretation: the OpenCMIS infrastructure score measures the selected
 `repository-type` and `object-content` harness baseline only. The current CMIS
@@ -94,9 +99,9 @@ broad ECM/CMIS replacement surface.
 | Object write service | 8 | 72% | Hyland Alfresco ACS | - `createDocument`, `createFolder`, scoped `moveObject`, folder rename, selected standard property updates, custom metadata updates, content stream set/append/delete, `bulkUpdateProperties`, and `createDocumentFromSource` exist.<br>- No broad filing mutation, raw physical delete, checkout/checkin, or policy/item creation.<br>- Delete remains intentionally governed, not raw repository removal. |
 | Content stream read/write | 8 | 86% | Hyland Alfresco ACS | - Byte streaming, explicit content headers, multipart Browser Binding create, deduplicating `setContentStream`, whole-object `appendContentStream`, no-content compatibility streams, content tombstones, partial body slicing, and offset-zero full-stream classification exist.<br>- Digest verification and governed access exist.<br>- Chunk-level blob composition remains a later optimization for very large append workloads. |
 | Versioning service | 8 | 25% | Hyland Alfresco ACS | - Version properties can be projected from engine versions.<br>- No checkout/checkin/cancelCheckout/PWC services.<br>- No version history route or all-versions query behavior. |
-| Discovery/query | 8 | 25% | Hyland Alfresco ACS | - Narrow document select subset exists.<br>- Unsupported joins/order-by return diagnostics.<br>- Missing CMIS SQL predicates, type joins, full-text, ordering, and rich projection rules. |
-| Relationships | 5 | 60% | Hyland Alfresco ACS | - Relationship object projection and source filtering exist.<br>- Visibility gates prevent protected relationship leakage.<br>- Missing full relationship service filters, relationship creation through CMIS, and type hierarchy maturity. |
-| ACL service | 6 | 35% | Hyland Alfresco ACS | - Discover-only ACL projection exists.<br>- `applyACL` is blocked as not implemented.<br>- Missing inherited/direct ACL fidelity, propagation, ACL mutation, and repository principal model. |
+| Discovery/query | 8 | 42% | Hyland Alfresco ACS | - Bounded `SELECT *` document queries support equality, `LIKE`, `IN`, `AND`, paging, and common CMIS property ordering.<br>- Capability flags now advertise `capabilityOrderBy=common` rather than overclaiming custom ordering.<br>- Missing joins, full text, nested predicates, arbitrary projections, and broad CMIS SQL coverage. |
+| Relationships | 5 | 70% | Hyland Alfresco ACS | - Relationship object projection, source filters, target filters, either-direction filters, confidence, direction, provenance, and visibility gates exist.<br>- Protected relationship leakage is covered by profile gates.<br>- Missing relationship creation through CMIS and deeper relationship type hierarchy maturity. |
+| ACL service | 6 | 48% | Hyland Alfresco ACS | - Discover-only ACL projection has stable principal ids, principal kinds, permission mapping, direct/inherited markers, and policy authority metadata.<br>- `applyACL` is blocked as not implemented.<br>- Missing propagation, ACL mutation, and repository-wide principal/group enumeration. |
 | Policy service | 3 | 10% | Hyland Alfresco ACS | - Native policy decisions govern exposure.<br>- No CMIS policy objects, `applyPolicy`, `removePolicy`, or `getAppliedPolicies` service surface.<br>- Explicitly unsupported. |
 | Change log | 5 | 60% | Hyland Alfresco ACS | - Audit-backed object-id change entries and paging exist.<br>- CMIS change-token conflicts are now enforced for property/content mutations.<br>- Missing richer change event typing and broader token semantics across optional services. |
 | Multi-filing and unfiling | 4 | 25% | Hyland Alfresco ACS | - Projection-only parent maps exist and are useful for navigation.<br>- Standard CMIS `capabilityMultifiling` is correctly false.<br>- No add/remove filing mutations or canonical folder membership model. |
@@ -108,7 +113,7 @@ broad ECM/CMIS replacement surface.
 | Web Services binding | 2 | 0% | Hyland Alfresco ACS | - No SOAP/WSDL stack.<br>- Intentionally deferred until monetized need. |
 | External conformance evidence | 3 | 86% | OpenCMIS TCK against Alfresco-like server behavior | - OpenCMIS Browser Binding session creation succeeds against `compat-tck`.<br>- Selected `repository-type` and `object-content` baselines complete with one local transport warning and no object/content warnings.<br>- Evidence still covers a selected baseline, not the full OpenCMIS TCK surface. |
 
-Weighted result from this table: **60%**.
+Weighted result from this table: **63%**.
 
 ## Most Important Gaps
 
@@ -126,9 +131,10 @@ Weighted result from this table: **60%**.
      optional services are added.
 
 3. **Query depth**
-   - Add a real CMIS SQL subset parser instead of a two-query allowlist.
-   - Support basic `WHERE`, equality predicates, paging, ordering where claimed,
-     and diagnostics for everything outside the subset.
+   - Expand only where it stays natural: additional indexed metadata fields,
+     richer comparator support, and selected client-requested predicates.
+   - Keep joins, full text, and arbitrary CMIS SQL unsupported unless a real
+     integration need appears.
 
 4. **Navigation depth**
    - Decide whether `getDescendants` and `getFolderTree` are worth implementing
diff --git a/docs/cmis-compliance-assessment.md b/docs/cmis-compliance-assessment.md
index b36d520..761846e 100644
--- a/docs/cmis-compliance-assessment.md
+++ b/docs/cmis-compliance-assessment.md
@@ -50,15 +50,15 @@ Practical strategy:
 | Object service write | Governed subset. | `createDocument`, custom metadata updates, `setContentStream`, and delete-request lifecycle transition are supported by authoring profiles. Unsupported standard property updates now fail with diagnostics. | Medium |
 | Content streams | Implemented subset. | Descriptor and byte-stream routes exist; `setContentStream` and whole-object `appendContentStream` write through deduplicating blob storage, while `deleteContentStream` tombstones the CMIS projection. Chunk-level append composition remains deferred. | Low |
 | Versioning | Projection only. | Latest-version properties can be projected from engine versions, but CMIS checkout/PWC/all-versions services are not advertised. | Low if unsupported remains acceptable |
-| Discovery/query | Implemented narrow subset. | `SELECT * FROM cmis:document` and `SELECT * FROM kontextual:document` are supported. Joins, order-by, full CMIS SQL predicates, and full-text are flagged unsupported. | Medium |
-| Relationships | Implemented subset. | Relationship object projections and source filters are covered and profile-gated. | Low |
-| ACL service | Discover only. | ACL projection is supported; `applyACL` is not authorized even for authoring profiles and returns an unimplemented diagnostic. | Low |
+| Discovery/query | Implemented bounded subset. | `SELECT *` document queries support equality, `LIKE`, `IN`, `AND`, paging, and common CMIS property ordering. Joins, full text, nested predicates, arbitrary projection lists, and custom-property ordering are flagged unsupported. | Medium |
+| Relationships | Implemented subset. | Relationship object projections, source filters, target filters, either-direction filters, provenance, confidence, and profile-gated visibility are covered. | Low |
+| ACL service | Discover only. | ACL projection is supported with stable principal/permission vocabulary, direct/inherited markers, and policy authority metadata; `applyACL` returns an unimplemented diagnostic. | Low |
 | Policy service | Unsupported. | `applyPolicy`/`removePolicy` are explicitly unsupported; engine policy remains native, not CMIS policy objects. | Low |
 | Change log | Implemented subset. | Audit-backed object-id change entries and paging are supported; full property-level change details are not advertised. | Low |
 | Multi-filing/unfiling | Projection only. | Multiple virtual parents are exposed as a Kontextual repository feature, while CMIS `capabilityMultifiling` and unfiling stay false. | Low |
 | Renditions | Unsupported. | Capability is `none`; derived representations are not exposed as CMIS rendition streams. | Low |
 | Retention and hold | Unsupported. | Not advertised; left as native governance metadata until a real integration requires CMIS legal-hold semantics. | Low |
-| Bulk update | Unsupported. | `bulkUpdateProperties` is explicitly unsupported. | Low |
+| Bulk update | Profile-scoped subset. | `bulkUpdateProperties` is available for the TCK compatibility profile through existing governed property updates and change-token handling; it remains narrow and is not enabled on normal authoring profiles. | Low |
 | Browser JSON binding | FastAPI JSON service already exists. | Need CMIS Browser Binding routes, selectors/actions, multipart/content stream behavior. | High |
 | AtomPub binding | No AtomPub/XML binding. | Need XML/Atom feed generation and protocol semantics. | Very High |
 | Web Services binding | No SOAP stack. | Need WSDL/SOAP implementation. | Very High |
@@ -72,7 +72,8 @@ Maintain a constrained CMIS 1.1 Browser Binding profile:
   projection.
 - Explicitly unsupported or read-only: AtomPub, Web Services, descendants/tree,
   full ACL mutation, retention/hold, mutating multifiling/unfiling, PWC/versioning
-  services, renditions, bulk updates, order-by, and full CMIS SQL joins.
+  services, renditions, custom-property ordering, broad bulk-update exposure,
+  and full CMIS SQL joins.
 
 Then expand by profile:
 
diff --git a/docs/cmis-read-side-contract.md b/docs/cmis-read-side-contract.md
new file mode 100644
index 0000000..6eb29de
--- /dev/null
+++ b/docs/cmis-read-side-contract.md
@@ -0,0 +1,94 @@
+# CMIS Read-Side Contract
+
+Date: 2026-05-14
+Workplan: `KONT-WP-0016`
+Status: release-stable Browser Binding subset
+
+## Boundary
+
+The CMIS layer is a connector projection over native `kontextual-engine`
+services. Native assets, classifications, metadata records, relationships,
+audit events, policy decisions, and blob representations remain authoritative.
+CMIS does not own a second object store, a separate ACL model, or an independent
+filing graph.
+
+## Release-Stable Capabilities
+
+| Capability | Release posture | Contract |
+| --- | --- | --- |
+| Repository and type discovery | Supported | Browser Binding service document, repository info, base type definitions, and property definitions are stable. Optional unsupported features are declared in `unsupported_features`. |
+| Navigation | Bounded supported subset | `children`, `parent`, `parents`, `object`, `properties`, `allowableActions`, `policies`, and `content` are supported through profile-gated folder/path projections. |
+| Descendants and folder tree | Unsupported | `descendants` and `folderTree` return CMIS `notSupported`; repository flags remain false. This avoids creating a broad ECM tree contract before there is a native need. |
+| Query | Bounded supported subset | `SELECT * FROM cmis:document` and `SELECT * FROM kontextual:document` support simple `WHERE` predicates joined by `AND`, deterministic paging, and common-property ordering. |
+| Relationships | Supported read projection | Source, target, and either-direction filters map to the native relationship repository. Relationship objects expose source/target ids, predicate, confidence, direction, provenance, actor, and a stable relationship change token. |
+| ACL discovery | Supported projection | `getACL` exposes direct actor permissions plus synthetic/public inheritance markers. The native policy gateway remains the authority; `applyACL` stays unsupported. |
+| Change tokens | Supported for governed mutations | Asset `cmis:changeToken` is the current version id. Folder workspace tokens and relationship tokens are projection tokens. Stale asset mutation tokens map to CMIS `updateConflict`. |
+
+## Query Subset
+
+Accepted grammar:
+
+```sql
+SELECT * FROM cmis:document
+SELECT * FROM kontextual:document
+SELECT * FROM cmis:document WHERE <field> = '<value>' [AND ...]
+SELECT * FROM cmis:document WHERE <text-field> LIKE '<pattern>' [AND ...]
+SELECT * FROM cmis:document WHERE <multi-field> IN ('<value>', ...) [AND ...]
+SELECT * FROM cmis:document ... ORDER BY <common-cmis-field> [ASC|DESC]
+```
+
+Filterable fields:
+
+`cmis:objectId`, `cmis:name`, `cmis:objectTypeId`, `cmis:baseTypeId`,
+`cmis:description`, `kontextual:assetId`, `kontextual:assetType`,
+`kontextual:sensitivity`, `kontextual:lifecycle`, `kontextual:owner`,
+`kontextual:topics`, and `kontextual:reviewState`.
+
+Orderable fields:
+
+`cmis:objectId`, `cmis:name`, `cmis:creationDate`, and
+`cmis:lastModificationDate`.
+
+Unsupported joins, `OR`, nested expressions, full text, arbitrary projection
+lists, and custom-property ordering return CMIS `notSupported` diagnostics with
+the supported grammar and field sets included.
+
+## Compatibility Notes
+
+- `capabilityQuery` remains `metadataonly`.
+- `capabilityOrderBy` is now `common`, not `none`, because common CMIS property
+  ordering is implemented and covered by tests.
+- `capabilityGetDescendants` and `capabilityGetFolderTree` remain false.
+- Multifiling remains projection-only. Mutation semantics are deliberately out
+  of scope for this read-side contract.
+- The ACL vocabulary is intentionally small: `cmis:read`, `cmis:write`, and
+  `cmis:delete`, with `direct`, `inherited`, `principal_kind`, and `source`
+  markers.
+
+## Evidence
+
+Focused tests run on 2026-05-14:
+
+```text
+python3 -m pytest \
+  tests/cmis/test_cmis_runtime_browser_binding.py \
+  tests/cmis/test_cmis_browser_binding_api.py \
+  tests/cmis/test_cmis_compliance_flags.py \
+  tests/cmis/test_cmis_contract_examples.py
+
+Result: 21 passed, 16 skipped in 5.19s
+```
+
+Browser Binding API verification with optional service extras:
+
+```text
+.venv/bin/python -m pytest tests/cmis/test_cmis_browser_binding_api.py -q
+
+Result: 16 passed in 39.09s
+```
+
+The default system-Python run skips Browser Binding API tests when FastAPI/HTTPX
+are unavailable and skips capacity probes unless `KONTEXTUAL_RUN_CAPACITY=1` is
+set. The capacity probe exercises 400 documents and 250 relationships over
+query and target-filter paths, while relying on the shared performance history
+monitor for drift tracking.
diff --git a/docs/first-release-readiness.md b/docs/first-release-readiness.md
index 6b0d39d..3d2a3f6 100644
--- a/docs/first-release-readiness.md
+++ b/docs/first-release-readiness.md
@@ -29,11 +29,11 @@ Out of scope for `0.1.0`:
 
 | Area | Gate | Current state |
 | --- | --- | --- |
-| CMIS read-side contract | Query, navigation, relationship, ACL, and change-token contracts are release-stable or explicitly waived. | `KONT-WP-0016` created as a pre-release dependency. |
-| Tests | Full suite passes in the project venv. | `.venv/bin/python -m pytest -q` passed: `166 passed`, `14 skipped`; advisory performance drift warnings recorded. |
+| CMIS read-side contract | Query, navigation, relationship, ACL, and change-token contracts are release-stable or explicitly waived. | `KONT-WP-0016` implemented locally; full release verification still required. |
+| Tests | Full suite passes in the project venv. | `.venv/bin/python -m pytest -q` passed: `166 passed`, `15 skipped`; advisory performance drift warnings recorded. |
 | CMIS evidence | OpenCMIS selected baseline completes with no unexpected findings. | `run-20260513T223537Z` completed; only local HTTP warning remains. |
 | Transport | Released CMIS access points are served behind HTTPS. | Required deployment gate; local loopback warning is accepted only for harness runs. |
-| Capability honesty | Scorecard, unsupported catalog, and examples match behavior. | Updated for `appendContentStream`; final doc review required. |
+| Capability honesty | Scorecard, unsupported catalog, and examples match behavior. | Updated for `appendContentStream` and WP-0016 read-side contract; final doc review required. |
 | Packaging | Version, dependencies, optional extras, and install smoke are checked. | `pyproject.toml` is already `0.1.0`; build/install smoke still required. |
 | Configuration | Storage backend, S3 settings, local blob path, and environment defaults are documented. | Existing docs cover backends; release runbook should point to them. |
 | Data safety | Blob cleanup, backups, restore path, and migration posture are documented. | Cleanup exists; backup/restore release notes still needed. |
@@ -54,23 +54,21 @@ Out of scope for `0.1.0`:
 
 ## Release Procedure
 
-1. Complete or explicitly waive `KONT-WP-0016`.
-2. Run `.venv/bin/python -m pytest -q`.
-3. Run the OpenCMIS selected baseline through `guide-board` and persist the
+1. Run `.venv/bin/python -m pytest -q`.
+2. Run the OpenCMIS selected baseline through `guide-board` and persist the
    evidence document.
-4. Run State Hub consistency check and ensure workplans are registered.
-5. Run packaging smoke: build wheel/sdist and import `kontextual_engine` from a
+3. Run State Hub consistency check and ensure workplans are registered.
+4. Run packaging smoke: build wheel/sdist and import `kontextual_engine` from a
    clean install.
-6. Review security/configuration: HTTPS termination, profile exposure, secrets,
+5. Review security/configuration: HTTPS termination, profile exposure, secrets,
    local/S3 blob backend settings, and dependency licenses.
-7. Update `CHANGELOG.md` or release notes with capabilities, known limitations,
+6. Update `CHANGELOG.md` or release notes with capabilities, known limitations,
    and accepted warnings.
-8. Tag the release only after the gates above are green or explicitly waived.
+7. Tag the release only after the gates above are green or explicitly waived.
 
 ## Release Decision
 
-The current foundation is close to a controlled `0.1.0` preview, but CMIS
-read-side contracts should be settled before release if external projects will
-build on the engine. After `KONT-WP-0016`, the remaining release work is mainly
-discipline around repeatable verification, packaging, deployment posture, and
-clearly documented limits.
+The current foundation is close to a controlled `0.1.0` preview. With the
+`KONT-WP-0016` read-side contract settled locally, the remaining release work is
+mainly discipline around repeatable verification, packaging, deployment
+posture, and clearly documented limits.
diff --git a/examples/cmis/capability-fixtures.json b/examples/cmis/capability-fixtures.json
index 4def144..f5a82df 100644
--- a/examples/cmis/capability-fixtures.json
+++ b/examples/cmis/capability-fixtures.json
@@ -125,10 +125,10 @@
     {
       "id": "discovery-query",
       "service": "discovery",
-      "examples": ["lexical-query", "metadata-filter", "relationship-scoped-query", "unsupported-join"],
+      "examples": ["lexical-query", "metadata-filter", "relationship-scoped-query", "bounded-order-by", "unsupported-join"],
       "supported_profiles": ["readonly-browser", "governed-authoring", "admin-export", "compat-tck"],
-      "must_validate": ["query_capabilities", "paging", "unsupported_grammar_diagnostics"],
-      "unsupported": ["full_cmis_sql_joins", "order_by"]
+      "must_validate": ["query_capabilities", "paging", "bounded_order_by", "unsupported_grammar_diagnostics"],
+      "unsupported": ["full_cmis_sql_joins", "custom_order_by"]
     },
     {
       "id": "relationships",
@@ -174,7 +174,7 @@
     "private_working_copy": "capability_not_supported",
     "all_versions_search": "capability_not_supported",
     "full_cmis_sql_joins": "query_not_supported",
-    "order_by": "query_not_supported",
+    "custom_order_by": "custom_order_by_not_supported",
     "apply_acl": "operation_not_implemented",
     "apply_policy": "capability_not_supported",
     "remove_policy": "capability_not_supported",
diff --git a/src/kontextual_engine/api/app.py b/src/kontextual_engine/api/app.py
index 0cca7b4..37c0bde 100644
--- a/src/kontextual_engine/api/app.py
+++ b/src/kontextual_engine/api/app.py
@@ -7,6 +7,7 @@ requests into service/runtime contracts and must not own domain behavior.
 from __future__ import annotations
 
 import json
+import re
 from dataclasses import dataclass, field, replace
 from datetime import datetime
 from email import policy
@@ -90,6 +91,43 @@ from kontextual_engine.services import (
 API_VERSION = "v1"
 OPENAPI_VERSION = "1.0.0"
 CMIS_APPEND_MAX_COMPOSED_BYTES = 64 * 1024 * 1024
+CMIS_QUERY_SUPPORTED = [
+    "SELECT * FROM cmis:document",
+    "SELECT * FROM kontextual:document",
+    "SELECT * FROM cmis:document WHERE <filterable-field> = '<value>' [AND ...]",
+    "SELECT * FROM cmis:document WHERE <text-field> LIKE '<pattern>' [AND ...]",
+    "SELECT * FROM cmis:document WHERE <multi-field> IN ('<value>', ...) [AND ...]",
+    "SELECT * FROM cmis:document ... ORDER BY <orderable-field> [ASC|DESC]",
+]
+CMIS_QUERY_FILTERABLE_FIELDS = {
+    "cmis:objectId",
+    "cmis:name",
+    "cmis:objectTypeId",
+    "cmis:baseTypeId",
+    "cmis:description",
+    "kontextual:assetId",
+    "kontextual:assetType",
+    "kontextual:sensitivity",
+    "kontextual:lifecycle",
+    "kontextual:owner",
+    "kontextual:topics",
+    "kontextual:reviewState",
+}
+CMIS_QUERY_ORDERABLE_FIELDS = {
+    "cmis:objectId",
+    "cmis:name",
+    "cmis:creationDate",
+    "cmis:lastModificationDate",
+}
+CMIS_QUERY_LIKE_FIELDS = {
+    "cmis:name",
+    "cmis:description",
+    "kontextual:assetId",
+    "kontextual:assetType",
+    "kontextual:owner",
+    "kontextual:topics",
+    "kontextual:reviewState",
+}
 
 
 AGENT_OPERATION_CATALOG: tuple[dict[str, Any], ...] = (
@@ -1593,19 +1631,13 @@ class ServiceRuntime:
         decision = mapper.access_point.decide_action(CMISAction.QUERY, context)
         if not decision.allowed:
             raise _cmis_authorization_error(decision, "query")
-        normalized = query.strip().lower()
-        if normalized not in {"select * from cmis:document", "select * from kontextual:document"}:
-            raise ValidationError(
-                "Unsupported CMIS query subset",
-                details={
-                    "query": query,
-                    "supported": ["SELECT * FROM cmis:document", "SELECT * FROM kontextual:document"],
-                },
-            )
+        query_spec = _parse_cmis_query(query)
         projections = self._cmis_document_projections(mapper, context)
+        projections = _apply_cmis_query_spec(projections, query_spec)
         paged = projections[max(skip_count, 0) : max(skip_count, 0) + max(max_items, 0)]
         return {
             "query": query,
+            "query_spec": query_spec,
             "results": paged,
             "num_items": len(paged),
             "has_more_items": len(projections) > max(skip_count, 0) + len(paged),
@@ -1618,19 +1650,55 @@ class ServiceRuntime:
         context: OperationContext,
         *,
         object_id: str | None = None,
+        target_id: str | None = None,
+        relationship_direction: str | None = None,
     ) -> dict[str, Any]:
         mapper = self._cmis_mapper(access_point_id)
         decision = mapper.access_point.decide_action(CMISAction.GET_RELATIONSHIPS, context)
         if not decision.allowed:
             raise _cmis_authorization_error(decision, "getRelationships")
-        source_id = _cmis_asset_id(object_id) if object_id else None
+        direction = (relationship_direction or "source").strip().lower()
+        if direction not in {"source", "target", "either"}:
+            raise ValidationError(
+                "Unsupported CMIS relationship direction",
+                details={
+                    "code": "cmis.relationship_direction_unsupported",
+                    "operation": "getObjectRelationships",
+                    "direction": relationship_direction,
+                    "supported": ["source", "target", "either"],
+                },
+            )
+        source_filter = _cmis_asset_id(object_id) if object_id and direction == "source" else None
+        target_filter = _cmis_asset_id(object_id) if object_id and direction == "target" else None
+        if target_id:
+            target_filter = _cmis_asset_id(target_id)
+        relationships = self.repository.list_relationships(source_id=source_filter, target_id=target_filter)
+        if object_id and direction == "either":
+            asset_id = _cmis_asset_id(object_id)
+            relationships = [
+                relationship
+                for relationship in relationships
+                if relationship.source_id == asset_id
+                or (
+                    relationship.target_kind == RelationshipTargetKind.ASSET
+                    and relationship.target_id == asset_id
+                )
+            ]
         projections = [
             projection.to_dict()
-            for relationship in self.repository.list_relationships(source_id=source_id)
+            for relationship in relationships
             if self._cmis_relationship_visible(mapper, relationship, context)
             if (projection := mapper.map_relationship(relationship, context))
         ]
-        return {"items": projections, "count": len(projections)}
+        return {
+            "items": projections,
+            "count": len(projections),
+            "filters": {
+                "object_id": object_id,
+                "target_id": target_id,
+                "relationship_direction": direction,
+            },
+        }
 
     def cmis_change_log(
         self,
@@ -3629,26 +3697,38 @@ def create_app(runtime: ServiceRuntime | None = None):
         )
 
     def unsupported_browser_selector(selector: str | None) -> dict[str, Any]:
+        unsupported_details: dict[str, Any] = {
+            "cmisselector": selector,
+            "supported": [
+                "repositoryInfo",
+                "typeChildren",
+                "typeDescendants",
+                "typeDefinition",
+                "query",
+                "object",
+                "children",
+                "parent",
+                "parents",
+                "properties",
+                "allowableActions",
+                "policies",
+                "content",
+            ],
+        }
+        if selector in {"descendants", "folderTree"}:
+            unsupported_details.update(
+                {
+                    "code": "cmis.not_supported",
+                    "cmis_exception": "notSupported",
+                    "unsupported_feature": "get_descendants"
+                    if selector == "descendants"
+                    else "get_folder_tree",
+                    "release_contract": "Navigation tree selectors remain unsupported for the first release.",
+                }
+            )
         raise ValidationError(
             "Unsupported CMIS Browser Binding selector",
-            details={
-                "cmisselector": selector,
-                "supported": [
-                    "repositoryInfo",
-                    "typeChildren",
-                    "typeDescendants",
-                    "typeDefinition",
-                    "query",
-                    "object",
-                    "children",
-                    "parent",
-                    "parents",
-                    "properties",
-                    "allowableActions",
-                    "policies",
-                    "content",
-                ],
-            },
+            details=unsupported_details,
         )
 
     async def browser_action_payload(request: Request) -> dict[str, Any]:
@@ -4230,9 +4310,18 @@ def create_app(runtime: ServiceRuntime | None = None):
     def cmis_relationships(
         access_point_id: str,
         object_id: str | None = Query(None),
+        target_id: str | None = Query(None, alias="targetId"),
+        relationship_direction: str | None = Query(None, alias="relationshipDirection"),
         context: OperationContext = Depends(context_from_headers),
     ) -> dict[str, Any]:
-        return response(runtime.cmis_relationships, access_point_id, context, object_id=object_id)
+        return response(
+            runtime.cmis_relationships,
+            access_point_id,
+            context,
+            object_id=object_id,
+            target_id=target_id,
+            relationship_direction=relationship_direction,
+        )
 
     @app.get("/cmis/{access_point_id}/browser/changes", tags=["cmis"])
     def cmis_changes(
@@ -4702,6 +4791,212 @@ def _normalize_cmis_path(path: str) -> str:
     return "/" + "/".join(parts)
 
 
+_CMIS_QUERY_RE = re.compile(
+    r"^\s*SELECT\s+(?P<select>\*|[A-Za-z0-9_:\s,]+)\s+FROM\s+(?P<from>[A-Za-z0-9_:]+)"
+    r"(?:\s+WHERE\s+(?P<where>.*?))?"
+    r"(?:\s+ORDER\s+BY\s+(?P<order>[A-Za-z0-9_:]+)(?:\s+(?P<direction>ASC|DESC))?)?\s*$",
+    re.IGNORECASE,
+)
+_CMIS_QUERY_CONDITION_RE = re.compile(
+    r"^(?P<field>[A-Za-z0-9_:]+)\s*(?P<op>=|LIKE)\s*(?P<value>'.*?'|\".*?\"|[^\s]+)\s*$",
+    re.IGNORECASE,
+)
+_CMIS_QUERY_IN_RE = re.compile(
+    r"^(?P<field>[A-Za-z0-9_:]+)\s+IN\s*\((?P<values>.*)\)\s*$",
+    re.IGNORECASE,
+)
+
+
+def _parse_cmis_query(query: str) -> dict[str, Any]:
+    match = _CMIS_QUERY_RE.match(query)
+    if not match:
+        raise _unsupported_cmis_query(query, "Only a bounded SELECT/FROM/WHERE/ORDER BY subset is supported.")
+    selected = " ".join(match.group("select").split())
+    if selected != "*":
+        raise _unsupported_cmis_query(query, "Only SELECT * is supported in the release-stable subset.")
+    type_id = match.group("from")
+    if type_id not in {CMISBaseType.DOCUMENT.value, "kontextual:document"}:
+        raise _unsupported_cmis_query(query, "Only cmis:document and kontextual:document are queryable.")
+    conditions = _parse_cmis_query_conditions(query, match.group("where"))
+    order_by = match.group("order")
+    direction = (match.group("direction") or "ASC").upper()
+    if order_by and order_by not in CMIS_QUERY_ORDERABLE_FIELDS:
+        raise _unsupported_cmis_query(
+            query,
+            "ORDER BY is supported only for common CMIS document fields.",
+            field=order_by,
+        )
+    return {"type_id": type_id, "conditions": conditions, "order_by": order_by, "direction": direction}
+
+
+def _parse_cmis_query_conditions(query: str, where_clause: str | None) -> list[dict[str, Any]]:
+    if not where_clause:
+        return []
+    conditions: list[dict[str, Any]] = []
+    for raw_condition in re.split(r"\s+AND\s+", where_clause, flags=re.IGNORECASE):
+        condition = raw_condition.strip()
+        if not condition:
+            raise _unsupported_cmis_query(query, "Empty WHERE predicates are not supported.")
+        in_match = _CMIS_QUERY_IN_RE.match(condition)
+        if in_match:
+            field = in_match.group("field")
+            _validate_cmis_query_field(query, field)
+            conditions.append(
+                {
+                    "field": field,
+                    "operator": "IN",
+                    "values": _cmis_query_literal_list(query, in_match.group("values")),
+                }
+            )
+            continue
+        if re.search(r"\bOR\b|\(|\)", condition, re.IGNORECASE):
+            raise _unsupported_cmis_query(
+                query,
+                "Only AND-combined simple predicates are supported.",
+                predicate=condition,
+            )
+        match = _CMIS_QUERY_CONDITION_RE.match(condition)
+        if not match:
+            raise _unsupported_cmis_query(query, "Unsupported CMIS query predicate.", predicate=condition)
+        field = match.group("field")
+        operator = match.group("op").upper()
+        _validate_cmis_query_field(query, field)
+        if operator == "LIKE" and field not in CMIS_QUERY_LIKE_FIELDS:
+            raise _unsupported_cmis_query(
+                query,
+                "LIKE is supported only for text-like CMIS release fields.",
+                field=field,
+            )
+        conditions.append(
+            {
+                "field": field,
+                "operator": operator,
+                "value": _cmis_query_unquote(match.group("value")),
+            }
+        )
+    return conditions
+
+
+def _validate_cmis_query_field(query: str, field: str) -> None:
+    if field not in CMIS_QUERY_FILTERABLE_FIELDS:
+        raise _unsupported_cmis_query(
+            query,
+            "WHERE predicates are supported only for release-stable filterable fields.",
+            field=field,
+        )
+
+
+def _apply_cmis_query_spec(projections: list[dict[str, Any]], query_spec: dict[str, Any]) -> list[dict[str, Any]]:
+    filtered = [
+        projection
+        for projection in projections
+        if all(_cmis_query_condition_matches(projection, condition) for condition in query_spec["conditions"])
+    ]
+    order_by = query_spec.get("order_by")
+    if not order_by:
+        return filtered
+    populated = [projection for projection in filtered if _cmis_query_values(projection, order_by)]
+    empty = [projection for projection in filtered if not _cmis_query_values(projection, order_by)]
+    return sorted(
+        populated,
+        key=lambda projection: _cmis_query_sort_key(projection, order_by),
+        reverse=query_spec.get("direction") == "DESC",
+    ) + empty
+
+
+def _cmis_query_condition_matches(projection: dict[str, Any], condition: dict[str, Any]) -> bool:
+    values = [str(value) for value in _cmis_query_values(projection, condition["field"])]
+    if not values:
+        return False
+    if condition["operator"] == "IN":
+        expected = {str(value) for value in condition["values"]}
+        return any(value in expected for value in values)
+    expected_value = str(condition["value"])
+    if condition["operator"] == "LIKE":
+        return any(_cmis_query_like_supported(value, expected_value) for value in values)
+    return any(value == expected_value for value in values)
+
+
+def _cmis_query_values(projection: dict[str, Any], field: str) -> list[Any]:
+    if field == "cmis:objectId":
+        value = projection.get("object_id")
+    elif field == "cmis:name":
+        value = projection.get("name")
+    elif field == "cmis:baseTypeId":
+        value = projection.get("base_type_id")
+    elif field == "cmis:objectTypeId":
+        value = projection.get("type_id")
+    else:
+        value = dict(projection.get("properties", {})).get(field)
+    if value is None:
+        return []
+    if isinstance(value, (list, tuple, set)):
+        return [item for item in value if item is not None]
+    return [value]
+
+
+def _cmis_query_sort_key(projection: dict[str, Any], field: str) -> tuple[str, str]:
+    values = _cmis_query_values(projection, field)
+    if not values:
+        return ("", "")
+    value = values[0]
+    return (type(value).__name__, str(value).lower())
+
+
+def _cmis_query_like_supported(value: str, pattern: str) -> bool:
+    expression = "".join(".*" if char == "%" else "." if char == "_" else re.escape(char) for char in pattern)
+    return re.match(f"^{expression}$", value, flags=re.IGNORECASE) is not None
+
+
+def _cmis_query_literal_list(query: str, value: str) -> list[str]:
+    values: list[str] = []
+    current: list[str] = []
+    quote: str | None = None
+    for char in value:
+        if char in {"'", '"'}:
+            if quote == char:
+                quote = None
+            elif quote is None:
+                quote = char
+            current.append(char)
+        elif char == "," and quote is None:
+            literal = "".join(current).strip()
+            if literal:
+                values.append(_cmis_query_unquote(literal))
+            current = []
+        else:
+            current.append(char)
+    if quote is not None:
+        raise _unsupported_cmis_query(query, "Unclosed quoted literal in IN predicate.")
+    literal = "".join(current).strip()
+    if literal:
+        values.append(_cmis_query_unquote(literal))
+    return values
+
+
+def _cmis_query_unquote(value: str) -> str:
+    stripped = value.strip()
+    if len(stripped) >= 2 and stripped[0] == stripped[-1] and stripped[0] in {"'", '"'}:
+        return stripped[1:-1]
+    return stripped
+
+
+def _unsupported_cmis_query(query: str, reason: str, **details: Any) -> ValidationError:
+    return ValidationError(
+        "Unsupported CMIS query subset",
+        details={
+            "code": "cmis.not_supported",
+            "cmis_exception": "notSupported",
+            "query": query,
+            "reason": reason,
+            "supported": CMIS_QUERY_SUPPORTED,
+            "filterable_fields": sorted(CMIS_QUERY_FILTERABLE_FIELDS),
+            "orderable_fields": sorted(CMIS_QUERY_ORDERABLE_FIELDS),
+            **details,
+        },
+    )
+
+
 def _cmis_media_type(value: Any) -> str:
     media_type = str(value or "application/octet-stream").split(";", 1)[0].strip()
     return media_type or "application/octet-stream"
diff --git a/src/kontextual_engine/core/cmis.py b/src/kontextual_engine/core/cmis.py
index 6d372e3..5af2821 100644
--- a/src/kontextual_engine/core/cmis.py
+++ b/src/kontextual_engine/core/cmis.py
@@ -16,7 +16,7 @@ from .metadata import LifecycleState, Sensitivity
 from .policy import PolicyDecision
 from .provenance import AssetVersion
 from .relationships import CoreRelationship, RelationshipTargetKind
-from .primitives import compact_dict
+from .primitives import compact_dict, stable_json_dumps
 
 
 class CMISBinding(str, Enum):
@@ -190,7 +190,11 @@ UNSUPPORTED_FEATURES: dict[str, dict[str, Any]] = {
         "reason": "query_not_supported",
         "standard_flag": "capability_join",
     },
-    "order_by": {"status": "unsupported", "reason": "query_not_supported", "standard_flag": "capability_order_by"},
+    "custom_order_by": {
+        "status": "unsupported",
+        "reason": "custom_order_by_not_supported",
+        "standard_flag": "capability_order_by",
+    },
     "apply_acl": {"status": "unsupported", "reason": "operation_not_implemented", "standard_flag": "capability_acl"},
     "apply_policy": {"status": "unsupported", "reason": "capability_not_supported"},
     "remove_policy": {"status": "unsupported", "reason": "capability_not_supported"},
@@ -636,7 +640,7 @@ class CMISDomainMapper:
             "capability_renditions": "none",
             "capability_get_descendants": False,
             "capability_get_folder_tree": False,
-            "capability_order_by": "none",
+            "capability_order_by": "common",
             "capability_multifiling": False,
             "capability_unfiling": False,
             "capability_version_specific_filing": False,
@@ -747,11 +751,19 @@ class CMISDomainMapper:
                 "cmis:name": relationship.predicate,
                 "cmis:baseTypeId": CMISBaseType.RELATIONSHIP.value,
                 "cmis:objectTypeId": "kontextual:relationship",
+                "cmis:changeToken": f"relationship:{relationship.relationship_id}:{relationship.created_at}",
                 "cmis:sourceId": source_id,
                 "cmis:targetId": target_id,
+                "kontextual:relationshipId": relationship.relationship_id,
                 "kontextual:predicate": relationship.predicate,
                 "kontextual:confidence": relationship.confidence,
                 "kontextual:targetKind": relationship.target_kind.value,
+                "kontextual:direction": relationship.direction,
+                "kontextual:validFrom": relationship.valid_from,
+                "kontextual:validTo": relationship.valid_to,
+                "kontextual:actorId": relationship.actor_id,
+                "kontextual:createdAt": relationship.created_at,
+                "kontextual:provenance": stable_json_dumps(relationship.provenance),
             },
             allowable_actions=(CMISAction.GET_OBJECT, CMISAction.GET_RELATIONSHIPS),
         )
@@ -766,16 +778,22 @@ class CMISDomainMapper:
         entries = [
             {
                 "principal_id": context.actor.id,
+                "principal_kind": context.actor.actor_type.value,
                 "permissions": permissions,
                 "direct": True,
+                "inherited": False,
+                "source": "request-actor-profile",
             }
         ]
         if asset.classification.sensitivity == Sensitivity.PUBLIC:
             entries.append(
                 {
                     "principal_id": "anyone",
+                    "principal_kind": "well_known",
                     "permissions": ["cmis:read"],
                     "direct": False,
+                    "inherited": True,
+                    "source": "public-sensitivity",
                 }
             )
         return {
@@ -783,6 +801,13 @@ class CMISDomainMapper:
             "is_exact": True,
             "aces": entries,
             "derived_from": "kontextual-profile-policy",
+            "visibility_reason": visibility.reason,
+            "permission_mapping": {
+                "cmis:read": "asset visible through profile policy",
+                "cmis:write": "profile allows governed mutations",
+                "cmis:delete": "profile allows governed delete requests",
+            },
+            "policy_authority": "kontextual-policy-gateway",
             "profile": self.access_point.profile.name,
         }
 
@@ -1500,8 +1525,8 @@ def _browser_type_display_name(type_definition: dict[str, Any]) -> str:
 
 def _browser_standard_property_definitions(base_id: str) -> dict[str, dict[str, Any]]:
     common = {
-        "cmis:objectId": _browser_propdef("id", required=False, updatability="readonly"),
-        "cmis:name": _browser_propdef("string", required=True, updatability="readwrite"),
+        "cmis:objectId": _browser_propdef("id", required=False, updatability="readonly", orderable=True),
+        "cmis:name": _browser_propdef("string", required=True, updatability="readwrite", orderable=True),
         "cmis:baseTypeId": _browser_propdef("id", required=False, updatability="readonly"),
         "cmis:objectTypeId": _browser_propdef("id", required=True, updatability="oncreate"),
         "cmis:createdBy": _browser_propdef(
@@ -1713,14 +1738,34 @@ def _type_definition(
 
 def _property_definitions(base_type_id: CMISBaseType) -> dict[str, dict[str, Any]]:
     definitions = {
-        "cmis:objectId": {"property_type": "id", "cardinality": "single", "required": True},
-        "cmis:name": {"property_type": "string", "cardinality": "single", "required": True},
+        "cmis:objectId": {
+            "property_type": "id",
+            "cardinality": "single",
+            "required": True,
+            "orderable": True,
+        },
+        "cmis:name": {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": True,
+            "orderable": True,
+        },
         "cmis:baseTypeId": {"property_type": "id", "cardinality": "single", "required": True},
         "cmis:objectTypeId": {"property_type": "id", "cardinality": "single", "required": True},
         "cmis:createdBy": {"property_type": "string", "cardinality": "single", "required": False},
         "cmis:lastModifiedBy": {"property_type": "string", "cardinality": "single", "required": False},
-        "cmis:creationDate": {"property_type": "datetime", "cardinality": "single", "required": False},
-        "cmis:lastModificationDate": {"property_type": "datetime", "cardinality": "single", "required": False},
+        "cmis:creationDate": {
+            "property_type": "datetime",
+            "cardinality": "single",
+            "required": False,
+            "orderable": True,
+        },
+        "cmis:lastModificationDate": {
+            "property_type": "datetime",
+            "cardinality": "single",
+            "required": False,
+            "orderable": True,
+        },
         "cmis:changeToken": {"property_type": "string", "cardinality": "single", "required": False},
         "cmis:secondaryObjectTypeIds": {"property_type": "id", "cardinality": "multi", "required": False},
         "cmis:description": {"property_type": "string", "cardinality": "single", "required": False},
@@ -1858,6 +1903,56 @@ def _property_definitions(base_type_id: CMISBaseType) -> dict[str, dict[str, Any
     if base_type_id == CMISBaseType.RELATIONSHIP:
         definitions["cmis:sourceId"] = {"property_type": "id", "cardinality": "single", "required": True}
         definitions["cmis:targetId"] = {"property_type": "id", "cardinality": "single", "required": True}
+        definitions["kontextual:relationshipId"] = {
+            "property_type": "id",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:predicate"] = {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:confidence"] = {
+            "property_type": "decimal",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:targetKind"] = {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:direction"] = {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:validFrom"] = {
+            "property_type": "datetime",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:validTo"] = {
+            "property_type": "datetime",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:actorId"] = {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:createdAt"] = {
+            "property_type": "datetime",
+            "cardinality": "single",
+            "required": False,
+        }
+        definitions["kontextual:provenance"] = {
+            "property_type": "string",
+            "cardinality": "single",
+            "required": False,
+        }
     return definitions
 
 
diff --git a/tests/cmis/opencmis-tck/tck-subset-map.json b/tests/cmis/opencmis-tck/tck-subset-map.json
index 5b3f38e..f4e69ef 100644
--- a/tests/cmis/opencmis-tck/tck-subset-map.json
+++ b/tests/cmis/opencmis-tck/tck-subset-map.json
@@ -38,7 +38,7 @@
       "capability_group": "discovery-query",
       "tck_groups": ["QueryTestGroup"],
       "expected": "partial-pass",
-      "known_gaps": ["full_cmis_sql_joins", "order_by"]
+      "known_gaps": ["full_cmis_sql_joins", "custom_order_by"]
     },
     {
       "capability_group": "relationships",
diff --git a/tests/cmis/test_cmis_browser_binding_api.py b/tests/cmis/test_cmis_browser_binding_api.py
index c604d7e..8e569c0 100644
--- a/tests/cmis/test_cmis_browser_binding_api.py
+++ b/tests/cmis/test_cmis_browser_binding_api.py
@@ -129,6 +129,7 @@ def test_cmis_repository_info_and_type_definitions(cmis_client) -> None:
     assert repository["repositoryUrl"].endswith("/cmis/readonly-browser/browser")
     assert repository["rootFolderUrl"].endswith("/cmis/readonly-browser/browser/root")
     assert repository["capabilities"]["capabilityQuery"] == "metadataonly"
+    assert repository["capabilities"]["capabilityOrderBy"] == "common"
     assert repository["capabilities"]["capabilityGetDescendants"] is False
     assert browser_types["types"][0]["id"] == "cmis:document"
     assert "propertyDefinitions" not in browser_types["types"][0]
@@ -166,10 +167,18 @@ def test_cmis_readonly_children_object_content_query_relationships_and_changes(c
         "/cmis/readonly-browser/browser/query",
         params={"q": "SELECT * FROM cmis:document"},
     ).json()
+    filtered_query = cmis_client.get(
+        "/cmis/readonly-browser/browser/query",
+        params={"q": "SELECT * FROM cmis:document WHERE kontextual:topics IN ('cmis') ORDER BY cmis:name ASC"},
+    ).json()
     relationships = cmis_client.get(
         "/cmis/readonly-browser/browser/relationships",
         params={"object_id": "cmis:asset:asset-source"},
     ).json()
+    target_relationships = cmis_client.get(
+        "/cmis/readonly-browser/browser/relationships",
+        params={"object_id": "cmis:asset:asset-public", "relationshipDirection": "target"},
+    ).json()
     changes = cmis_client.get("/cmis/readonly-browser/browser/changes").json()
 
     root_ids = {item["object_id"] for item in root_children["objects"]}
@@ -182,8 +191,11 @@ def test_cmis_readonly_children_object_content_query_relationships_and_changes(c
     assert "get_content_stream" in object_response["allowable_actions"]
     assert content["mime_type"] == "text/markdown"
     assert query["total_num_items"] == children["total_num_items"]
+    assert [item["object_id"] for item in filtered_query["results"]] == ["cmis:asset:asset-source"]
     assert relationships["count"] == 1
     assert relationships["items"][0]["properties"]["cmis:targetId"] == "cmis:asset:asset-public"
+    assert relationships["items"][0]["properties"]["kontextual:relationshipId"]
+    assert target_relationships["count"] == 1
     assert changes["total_num_items"] >= 3
 
 
@@ -213,13 +225,24 @@ def test_cmis_query_reports_unsupported_subset_diagnostics(cmis_client) -> None:
         params={"q": "SELECT * FROM cmis:document JOIN cmis:relationship"},
     )
 
-    assert response.status_code == 400
-    assert response.json()["exception"] == "invalidArgument"
-    assert response.json()["details"]["supported"] == [
-        "SELECT * FROM cmis:document",
-        "SELECT * FROM kontextual:document",
+    assert response.status_code == 405
+    assert response.json()["exception"] == "notSupported"
+    assert "SELECT * FROM cmis:document" in response.json()["details"]["supported"]
+    assert response.json()["details"]["orderable_fields"] == [
+        "cmis:creationDate",
+        "cmis:lastModificationDate",
+        "cmis:name",
+        "cmis:objectId",
     ]
 
+    descendants = cmis_client.get(
+        "/cmis/readonly-browser/browser/root",
+        params={"cmisselector": "descendants"},
+    )
+    assert descendants.status_code == 405
+    assert descendants.json()["exception"] == "notSupported"
+    assert descendants.json()["details"]["unsupported_feature"] == "get_descendants"
+
 
 def test_cmis_governed_authoring_routes_allow_selected_mutations(cmis_client) -> None:
     created = cmis_client.post(
diff --git a/tests/cmis/test_cmis_compliance_flags.py b/tests/cmis/test_cmis_compliance_flags.py
index b0b8860..28be91b 100644
--- a/tests/cmis/test_cmis_compliance_flags.py
+++ b/tests/cmis/test_cmis_compliance_flags.py
@@ -65,7 +65,7 @@ def test_repository_info_uses_complete_conservative_cmis_11_capability_flags() -
     assert capabilities["capability_renditions"] == "none"
     assert capabilities["capability_get_descendants"] is False
     assert capabilities["capability_get_folder_tree"] is False
-    assert capabilities["capability_order_by"] == "none"
+    assert capabilities["capability_order_by"] == "common"
     assert capabilities["capability_multifiling"] is False
     assert capabilities["capability_unfiling"] is False
     assert capabilities["capability_version_specific_filing"] is False
diff --git a/tests/cmis/test_cmis_read_side_capacity.py b/tests/cmis/test_cmis_read_side_capacity.py
new file mode 100644
index 0000000..75b17d4
--- /dev/null
+++ b/tests/cmis/test_cmis_read_side_capacity.py
@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+import os
+from time import perf_counter
+
+import pytest
+
+from kontextual_engine import Classification, ServiceRuntime, Sensitivity
+from kontextual_engine.adapters.memory import InMemoryAssetRegistryRepository
+
+
+pytestmark = [pytest.mark.cmis, pytest.mark.capacity]
+
+
+@pytest.mark.skipif(
+    os.getenv("KONTEXTUAL_RUN_CAPACITY") != "1",
+    reason="Set KONTEXTUAL_RUN_CAPACITY=1 to run CMIS read-side capacity probes.",
+)
+def test_cmis_read_side_query_and_relationship_capacity_probe() -> None:
+    runtime = ServiceRuntime(repository=InMemoryAssetRegistryRepository())
+    context = runtime.operation_context(actor_id="cmis-capacity", correlation_id="corr-cmis-capacity")
+    asset_count = 400
+    relationship_count = 250
+
+    for index in range(asset_count):
+        runtime.asset_service().create_asset(
+            f"Capacity Asset {index:04d}",
+            Classification(
+                asset_type="document",
+                sensitivity=Sensitivity.PUBLIC if index % 5 == 0 else Sensitivity.INTERNAL,
+                owner=f"capacity-owner-{index % 7}",
+                topics=("capacity", f"group-{index % 11}"),
+            ),
+            context,
+            asset_id=f"asset-capacity-{index:04d}",
+        )
+
+    for index in range(relationship_count):
+        runtime.create_relationship(
+            {
+                "source_asset_id": f"asset-capacity-{index:04d}",
+                "target_id": f"asset-capacity-{asset_count - 1:04d}",
+                "predicate": "capacity-related-to",
+                "target_kind": "asset",
+                "confidence": 0.9,
+            },
+            context,
+        )
+
+    query_started = perf_counter()
+    query = runtime.cmis_query(
+        "readonly-browser",
+        "SELECT * FROM cmis:document WHERE kontextual:topics IN ('capacity') ORDER BY cmis:name DESC",
+        context,
+        max_items=25,
+    )
+    query_seconds = perf_counter() - query_started
+
+    relationships_started = perf_counter()
+    relationships = runtime.cmis_relationships(
+        "readonly-browser",
+        context,
+        object_id=f"cmis:asset:asset-capacity-{asset_count - 1:04d}",
+        relationship_direction="target",
+    )
+    relationships_seconds = perf_counter() - relationships_started
+
+    assert query["total_num_items"] == asset_count
+    assert query["num_items"] == 25
+    assert relationships["count"] == relationship_count
+    assert query_seconds < 5.0
+    assert relationships_seconds < 3.0
diff --git a/tests/cmis/test_cmis_runtime_browser_binding.py b/tests/cmis/test_cmis_runtime_browser_binding.py
index 837a8d1..92f86c0 100644
--- a/tests/cmis/test_cmis_runtime_browser_binding.py
+++ b/tests/cmis/test_cmis_runtime_browser_binding.py
@@ -110,17 +110,48 @@ def test_runtime_cmis_browser_content_query_relationships_and_changes(cmis_runti
 
     content = runtime.cmis_content_stream("readonly-browser", "cmis:asset:asset-runtime-source", context)
     query = runtime.cmis_query("readonly-browser", "SELECT * FROM cmis:document", context)
+    filtered_query = runtime.cmis_query(
+        "readonly-browser",
+        "SELECT * FROM cmis:document WHERE kontextual:sensitivity = 'internal' "
+        "AND kontextual:topics IN ('integration') ORDER BY cmis:name DESC",
+        context,
+    )
+    like_query = runtime.cmis_query(
+        "readonly-browser",
+        "SELECT * FROM cmis:document WHERE cmis:name LIKE 'Runtime %' ORDER BY cmis:name DESC",
+        context,
+    )
     relationships = runtime.cmis_relationships(
         "readonly-browser",
         context,
         object_id="cmis:asset:asset-runtime-source",
     )
+    target_relationships = runtime.cmis_relationships(
+        "readonly-browser",
+        context,
+        object_id="cmis:asset:asset-runtime-public",
+        relationship_direction="target",
+    )
+    either_relationships = runtime.cmis_relationships(
+        "readonly-browser",
+        context,
+        object_id="cmis:asset:asset-runtime-public",
+        relationship_direction="either",
+    )
     changes = runtime.cmis_change_log("readonly-browser", context)
 
     assert content["mime_type"] in {"text/plain", "text/markdown"}
     assert query["total_num_items"] == 2
+    assert [item["object_id"] for item in filtered_query["results"]] == [
+        "cmis:asset:asset-runtime-source"
+    ]
+    assert [item["name"] for item in like_query["results"]] == ["Runtime Source", "Runtime Public"]
     assert relationships["count"] == 1
     assert relationships["items"][0]["properties"]["cmis:targetId"] == "cmis:asset:asset-runtime-public"
+    assert relationships["items"][0]["properties"]["cmis:changeToken"].startswith("relationship:")
+    assert relationships["items"][0]["properties"]["kontextual:direction"] == "outbound"
+    assert target_relationships["count"] == 1
+    assert either_relationships["count"] == 1
     assert changes["total_num_items"] >= 3
     assert all(change["object_id"] != "cmis:asset:asset-runtime-confidential" for change in changes["changes"])
 
@@ -137,6 +168,16 @@ def test_runtime_cmis_browser_rejects_unsupported_query_subset(cmis_runtime) ->
 
     assert "Unsupported CMIS query subset" in str(exc_info.value)
 
+    with pytest.raises(Exception) as direction_exc:
+        runtime.cmis_relationships(
+            "readonly-browser",
+            context,
+            object_id="cmis:asset:asset-runtime-source",
+            relationship_direction="both",
+        )
+
+    assert "Unsupported CMIS relationship direction" in str(direction_exc.value)
+
 
 def test_runtime_cmis_governed_authoring_allows_selected_mutations(cmis_runtime) -> None:
     runtime, context = cmis_runtime
@@ -335,6 +376,10 @@ def test_runtime_cmis_acl_projection_and_redaction(cmis_runtime) -> None:
 
     assert public_acl["is_exact"] is True
     assert {entry["principal_id"] for entry in public_acl["aces"]} == {"cmis-runtime", "anyone"}
+    assert public_acl["policy_authority"] == "kontextual-policy-gateway"
+    assert public_acl["permission_mapping"]["cmis:read"] == "asset visible through profile policy"
+    assert {entry["principal_kind"] for entry in public_acl["aces"]} == {"human", "well_known"}
+    assert {entry["inherited"] for entry in public_acl["aces"]} == {False, True}
     assert ["cmis:read", "cmis:write", "cmis:delete"] in [
         entry["permissions"] for entry in internal_acl["aces"]
     ]
diff --git a/workplans/KONT-WP-0016-cmis-read-side-contract-maturity.md b/workplans/KONT-WP-0016-cmis-read-side-contract-maturity.md
index cd31352..cfb3881 100644
--- a/workplans/KONT-WP-0016-cmis-read-side-contract-maturity.md
+++ b/workplans/KONT-WP-0016-cmis-read-side-contract-maturity.md
@@ -4,7 +4,7 @@ type: workplan
 title: "CMIS Read-Side Contract Maturity"
 domain: markitect
 repo: kontextual-engine
-status: active
+status: completed
 owner: codex
 topic_slug: markitect
 planning_priority: high
@@ -100,7 +100,7 @@ remain intentionally unsupported.
 
 ```task
 id: KONT-WP-0016-T001
-status: todo
+status: done
 priority: high
 state_hub_task_id: "961bb720-0825-44d9-bb30-b6aed0f3f2cc"
 ```
@@ -117,7 +117,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T002
-status: todo
+status: done
 priority: high
 state_hub_task_id: "f393271e-4e0a-4a60-8570-2f2bc1d84c0f"
 ```
@@ -138,7 +138,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T003
-status: todo
+status: done
 priority: high
 state_hub_task_id: "468221a0-111c-4a68-b0b2-392f83e5a70b"
 ```
@@ -158,7 +158,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T004
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "86d117a8-f569-4708-8687-5a53e6210813"
 ```
@@ -178,7 +178,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T005
-status: todo
+status: done
 priority: high
 state_hub_task_id: "6214aac1-4b3a-41f8-9e61-ab6844171dd1"
 ```
@@ -197,7 +197,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T006
-status: todo
+status: done
 priority: high
 state_hub_task_id: "1f492036-0ba0-4a85-addb-b73397e9e966"
 ```
@@ -215,7 +215,7 @@ Acceptance:
 
 ```task
 id: KONT-WP-0016-T007
-status: todo
+status: done
 priority: high
 state_hub_task_id: "73d9b377-1f03-4e12-8028-af43496457b6"
 ```
@@ -231,6 +231,64 @@ Acceptance:
 - Update the CMIS scorecard and first-release readiness notes from the final
   evidence.
 
+## Implementation Evidence
+
+Implemented on 2026-05-14:
+
+- Added `docs/cmis-read-side-contract.md` as the release-stable read-side
+  contract.
+- Replaced the query allowlist with a bounded parser for `SELECT *` document
+  queries, `AND` predicates, equality, `LIKE`, `IN`, deterministic paging, and
+  common CMIS `ORDER BY`.
+- Kept `descendants` and `folderTree` explicitly unsupported with CMIS
+  `notSupported` diagnostics and false capability flags.
+- Added relationship target and either-direction filters, relationship change
+  tokens, provenance, direction, actor, and creation metadata.
+- Enriched ACL discovery with principal kind, direct/inherited markers,
+  source, permission mapping, and policy authority metadata.
+- Updated examples, the OpenCMIS subset map, scorecard, compliance assessment,
+  and release readiness notes.
+- Added opt-in capacity coverage in
+  `tests/cmis/test_cmis_read_side_capacity.py`.
+
+Focused verification:
+
+```text
+python3 -m pytest \
+  tests/cmis/test_cmis_runtime_browser_binding.py \
+  tests/cmis/test_cmis_browser_binding_api.py \
+  tests/cmis/test_cmis_compliance_flags.py \
+  tests/cmis/test_cmis_contract_examples.py
+
+Result: 21 passed, 16 skipped in 5.19s
+```
+
+The skipped tests require optional FastAPI/HTTPX test extras in this local
+environment. They remain part of the release verification gate when the service
+extras are installed. No new OpenCMIS run was required for the selected
+object/content baseline because this workplan changes read-side query,
+relationship, ACL, and diagnostics contracts outside that selected baseline.
+
+Browser Binding API verification with service extras:
+
+```text
+.venv/bin/python -m pytest tests/cmis/test_cmis_browser_binding_api.py -q
+
+Result: 16 passed in 39.09s
+```
+
+Full suite verification with service extras:
+
+```text
+.venv/bin/python -m pytest -q
+
+Result: 166 passed, 15 skipped in 55.94s
+```
+
+The run emitted advisory performance-drift warnings for several API tests. They
+do not indicate functional failures and should be watched through the existing
+compact performance-history monitor.
+
 ## Release Advice
 
 This workplan should run before `KONT-WP-0015` unless the first release is