diff --git a/api/openapi.json b/api/openapi.json
index d0badfb..2ef0bc1 100644
--- a/api/openapi.json
+++ b/api/openapi.json
@@ -4374,16 +4374,6 @@
                 }
               }
             }
-          },
-          "500": {
-            "description": "Internal Server Error",
-            "content": {
-              "application/problem+json": {
-                "schema": {
-                  "$ref": "#/components/schemas/ProblemDetail"
-                }
-              }
-            }
           }
         }
       }
diff --git a/docs/reference/api-design-v4_0_1.md b/docs/reference/api-design-v4_0_1.md
index a03007d..b7f9f92 100644
--- a/docs/reference/api-design-v4_0_1.md
+++ b/docs/reference/api-design-v4_0_1.md
@@ -88,6 +88,7 @@ GET /api/v1/scans/{scan_id}/events
 - Job statuses: `queued`, `running`, `completed`, `partial`, `failed`, `canceled`.
 - Task statuses: `queued`, `running`, `completed`, `failed`, `skipped`, `blocked`, `canceled`.
 - A ScanResult belongs to one ScanTask, not directly to the ScanJob.
+- A ScanResult carries an optional `trend`: movement against the previous result for the same test, as a `direction` (`improving`, `unchanged`, `declining`), a signed `delta`, and the id of the compared result. It tracks `grade` where the test is graded and total findings where it is not. Computed at read time; null on the first result for a test, or once the predecessor has been purged.
 - Specific causes use stable machine-readable `status_reason` values. Labels, descriptions, localization, and operator guidance stay code-owned.
 - A task timeout produces `failed` with a timeout `status_reason`. A job timeout terminates unfinished work; the job becomes `partial` when usable results exist, otherwise `failed`.
 - `POST /scans/{scan_id}/cancel` records cancellation intent and preserves scan history. `DELETE` is never used to stop execution.
diff --git a/docs/reference/data-model-v4_0_1.md b/docs/reference/data-model-v4_0_1.md
index 52360b5..7549e7e 100644
--- a/docs/reference/data-model-v4_0_1.md
+++ b/docs/reference/data-model-v4_0_1.md
@@ -531,6 +531,7 @@ Constraints:
 - `grade` is used only for Email, Web headers, and Web TLS tasks.
 - Non-graded tasks use severity counts or per-step verdicts in `summary`.
 - No cross-module composite score is stored.
+- The API-level `ScanResult.trend` (`TrendDirection`: `improving`, `unchanged`, `declining`) is computed at read time from the previous comparable result and is not stored. No PostgreSQL enum carries it, like the computed verification status (§4.2).
 
 ### 8.2 `finding`
 
diff --git a/src/nc3_testing_platform/domains/assets/examples.py b/src/nc3_testing_platform/domains/assets/examples.py
index ef63657..d6c2c16 100644
--- a/src/nc3_testing_platform/domains/assets/examples.py
+++ b/src/nc3_testing_platform/domains/assets/examples.py
@@ -32,6 +32,15 @@
 _T0 = datetime(2026, 6, 1, 8, 30, tzinfo=UTC)
 _T1 = datetime(2026, 7, 31, 9, 1, 12, tzinfo=UTC)
 
+# The challenge is younger than the proof: its answer window must still be open at
+# the _T1 recheck, or a `pending` sample would carry an unanswerable challenge.
+# VERIFICATION_TOKEN_TTL is env-configurable, so the invariant is asserted rather
+# than assumed — a TTL short enough to close the window fails at import.
+_CHALLENGE_REQUESTED_AT = datetime(2026, 7, 28, 8, 30, tzinfo=UTC)
+assert _CHALLENGE_REQUESTED_AT + VERIFICATION_TOKEN_TTL > _T1
+
+_FEED_REVOKED_AT = datetime(2026, 7, 31, 10, 0, tzinfo=UTC)
+
 _SUBDOMAIN_ASSET_ID = UUID("019ee1a3-0011-7a22-8b33-4c44d5e66f77")
 _CHALLENGE_ID = UUID("019ee1a3-1122-7b33-9c44-5d55e6f77a88")
 _FEED_ID = UUID("019ee1a3-2233-7c44-ad55-6e66f7a88b99")
@@ -82,9 +91,9 @@ def sample_challenge(checked: bool = False) -> VerificationChallenge:
         requested_scope=VerificationScope.ZONE,
         record_name=verification_record_name("example.lu"),
         verification_token="verify-4f7a2c9e1b8d3056",
-        token_expires_at=_T0 + VERIFICATION_TOKEN_TTL,
+        token_expires_at=_CHALLENGE_REQUESTED_AT + VERIFICATION_TOKEN_TTL,
         requested_by_user_id=USER_ID,
-        requested_at=_T0,
+        requested_at=_CHALLENGE_REQUESTED_AT,
         last_recheck_at=_T1 if checked else None,
         failure_code="dns.txt_record_not_found" if checked else None,
     )
@@ -128,6 +137,13 @@ def sample_feed() -> AssetFeed:
     )
 
 
+def revoked_feed() -> AssetFeed:
+    """The feed after revocation, revoked after its last delivery."""
+    feed = sample_feed()
+    feed.revoked_at = _FEED_REVOKED_AT
+    return feed
+
+
 def sample_feed_created() -> AssetFeedCreated:
     """The one response that carries the plaintext token."""
     return AssetFeedCreated(
diff --git a/src/nc3_testing_platform/domains/assets/router.py b/src/nc3_testing_platform/domains/assets/router.py
index f944ba1..b8b0b93 100644
--- a/src/nc3_testing_platform/domains/assets/router.py
+++ b/src/nc3_testing_platform/domains/assets/router.py
@@ -237,9 +237,7 @@ async def revoke_asset_feed(asset_id: ResourceId, feed_id: ResourceId) -> AssetF
     A `POST` rather than a `DELETE`, because revocation is a recorded event and the
     lifecycle survives it.
     """
-    feed = examples.sample_feed()
-    feed.revoked_at = feed.created_at
-    return feed
+    return examples.revoked_feed()
 
 
 @public_feed_router.get(
diff --git a/src/nc3_testing_platform/domains/scans/examples.py b/src/nc3_testing_platform/domains/scans/examples.py
index 3f2f014..ac3c417 100644
--- a/src/nc3_testing_platform/domains/scans/examples.py
+++ b/src/nc3_testing_platform/domains/scans/examples.py
@@ -199,6 +199,17 @@ def sample_job(
     )
 
 
+def canceled_job() -> ScanJob:
+    """The job once cancellation intent has taken effect.
+
+    `canceled` appears in no other sample, and the cancel response is where a
+    client learns the terminal shape it must render.
+    """
+    job = sample_job(status=ScanJobStatus.CANCELED)
+    job.status_reason = "scan.canceled_by_user"
+    return job
+
+
 def sample_job_detail() -> ScanJobDetail:
     """The job/task snapshot a live-progress client fetches before subscribing."""
     return ScanJobDetail(**sample_job().model_dump(), tasks=sample_tasks())
diff --git a/src/nc3_testing_platform/domains/scans/router.py b/src/nc3_testing_platform/domains/scans/router.py
index 940ffe3..021fb9c 100644
--- a/src/nc3_testing_platform/domains/scans/router.py
+++ b/src/nc3_testing_platform/domains/scans/router.py
@@ -275,7 +275,7 @@ async def cancel_scan(scan_id: ResourceId) -> ScanJob:
     safe interruption points; a canceled task cannot later produce an accepted
     successful result.
     """
-    return examples.sample_job()
+    return examples.canceled_job()
 
 
 @router.post(
diff --git a/src/nc3_testing_platform/domains/statements/router.py b/src/nc3_testing_platform/domains/statements/router.py
index 890333a..32d9377 100644
--- a/src/nc3_testing_platform/domains/statements/router.py
+++ b/src/nc3_testing_platform/domains/statements/router.py
@@ -24,7 +24,6 @@
 @router.get(
     "/statements",
     summary="List active statements",
-    responses=problem_responses(500),
 )
 async def list_statements() -> list[Statement]:
     """Statements currently in force.