diff --git a/crates/utopia-server/src/api/sources_cleanup_tests.rs b/crates/utopia-server/src/api/sources_cleanup_tests.rs
new file mode 100644
index 000000000..5a2e7f7bf
--- /dev/null
+++ b/crates/utopia-server/src/api/sources_cleanup_tests.rs
@@ -0,0 +1,300 @@
+//! 墓碑清理之后，派生要跟上（#875）。`DELETE /documents/{id}` 删完一篇就按库的开关重推一遍
+//! （`settle_derivations`：删除、撤销、同步复活共用）；`POST .../missing/cleanup` 一次删一批
+//! 墓碑文档，从前删完却不重推——凭这些文档成立的结论照旧挂着，直到下一轮定时推导。
+//! 同一份夹具两条路各走一遍，单篇删除是对照。
+//!
+//! 连库的测试，没有 `UTOPIA_DATABASE_URL` 就跳过（同 documents_routes_tests）。
+
+use axum::body::{to_bytes, Body};
+use axum::http::{Request, StatusCode};
+use serde_json::{json, Value};
+use std::sync::Arc;
+use tower::ServiceExt;
+use utopia_core::models::RelationAxioms;
+use utopia_store::business_rules::ConditionInput;
+use utopia_store::graph::Validity;
+use uuid::Uuid;
+
+struct Fixture {
+    pool: sqlx::PgPool,
+    app: axum::Router,
+    org: Uuid,
+    kb: Uuid,
+    source: Uuid,
+    token: String,
+    cup: Uuid,
+    location: Uuid,
+    _dir: tempfile::TempDir,
+}
+
+impl Fixture {
+    async fn new() -> anyhow::Result<Option<Self>> {
+        let Some(url) = utopia_store::test_db::url() else {
+            return Ok(None);
+        };
+        let pool = sqlx::PgPool::connect(&url).await?;
+        utopia_store::db::migrate(&pool).await?;
+        let (org, ws, kb, user, source) = (
+            Uuid::now_v7(),
+            Uuid::now_v7(),
+            Uuid::now_v7(),
+            Uuid::now_v7(),
+            Uuid::now_v7(),
+        );
+        // Only locally generated UUIDs are interpolated into fixture SQL.
+        // The base keeps the column default: materialized inference is on (0050).
+        sqlx::raw_sql(&format!(
+            "INSERT INTO organizations(id,name) VALUES ('{org}','cleanup-settle-test');
+             INSERT INTO workspaces(id,org_id,name) VALUES ('{ws}','{org}','cleanup-settle-test');
+             INSERT INTO users(id,org_id,email,display_name,password_hash)
+                 VALUES ('{user}','{org}','{user}@cleanup.test','cleanup-test','unused');
+             INSERT INTO knowledge_bases(id,workspace_id,name) VALUES ('{kb}','{ws}','observations');
+             INSERT INTO kb_members(kb_id,user_id,role) VALUES ('{kb}','{user}','editor');
+             INSERT INTO sources(id,kb_id,kind,name) VALUES ('{source}','{kb}','api','robot-1');"
+        ))
+        .execute(&pool)
+        .await?;
+        let cup = utopia_store::ontology::create_entity_type(
+            &pool,
+            kb,
+            "cup",
+            "Cup",
+            "#7fd0ff",
+            "circle",
+            &[],
+            "",
+        )
+        .await?;
+        let ready = utopia_store::ontology::create_entity_type(
+            &pool,
+            kb,
+            "step_ready",
+            "Step precondition holds",
+            "#7fd0ff",
+            "circle",
+            &[],
+            "",
+        )
+        .await?;
+        let location = utopia_store::ontology::create_relation_type(
+            &pool,
+            kb,
+            "location",
+            "location",
+            "state",
+            RelationAxioms {
+                functional: true,
+                ..Default::default()
+            },
+            "",
+            "attribute",
+            &[cup],
+            &[],
+            Some("text"),
+            None,
+        )
+        .await?;
+        utopia_store::business_rules::create(
+            &pool,
+            kb,
+            "pick cup from desk",
+            "",
+            cup,
+            "typing",
+            Some(ready),
+            None,
+            None,
+            None,
+            &[ConditionInput {
+                group: 0,
+                predicate_id: location,
+                op: "in".into(),
+                operand: Some(json!(["desk"])),
+            }],
+        )
+        .await?;
+        let dir = tempfile::tempdir()?;
+        let cfg = utopia_core::config::AppConfig {
+            data_dir: dir.path().to_string_lossy().into_owned(),
+            ..Default::default()
+        };
+        let search = Arc::new(utopia_search::SearchIndex::open(
+            &dir.path().join("search"),
+        )?);
+        let state = crate::state::AppState::new(pool.clone(), &cfg, search, "test-only".into());
+        let token = crate::auth::issue_token(&state, user)?;
+        let app = super::super::router(state.clone(), &cfg);
+        Ok(Some(Self {
+            pool,
+            app,
+            org,
+            kb,
+            source,
+            token,
+            cup,
+            location,
+            _dir: dir,
+        }))
+    }
+
+    /// 一样东西、一份挂在来源下的文档、一条以那份文档为唯一证据的读数「在桌上」
+    async fn reading(&self, name: &str) -> anyhow::Result<(Uuid, Uuid, Uuid)> {
+        let (doc, chunk, thing) = (Uuid::now_v7(), Uuid::now_v7(), Uuid::now_v7());
+        sqlx::query(
+            "INSERT INTO documents (id, kb_id, source_id, filename, sha256, external_key, status)
+             VALUES ($1, $2, $3, $4, $5, $6, 'ready')",
+        )
+        .bind(doc)
+        .bind(self.kb)
+        .bind(self.source)
+        .bind(format!("{name}.json"))
+        .bind(format!("sha-{doc}"))
+        .bind(format!("api:{name}"))
+        .execute(&self.pool)
+        .await?;
+        sqlx::query(
+            "INSERT INTO chunks (id, kb_id, document_id, seq, text) VALUES ($1, $2, $3, 0, $4)",
+        )
+        .bind(chunk)
+        .bind(self.kb)
+        .bind(doc)
+        .bind(format!("{name} is on desk"))
+        .execute(&self.pool)
+        .await?;
+        sqlx::query(
+            "INSERT INTO entities (id, kb_id, type_id, canonical_name) VALUES ($1, $2, $3, $4)",
+        )
+        .bind(thing)
+        .bind(self.kb)
+        .bind(self.cup)
+        .bind(name)
+        .execute(&self.pool)
+        .await?;
+        let (fact, _) = utopia_store::graph::insert_value_fact(
+            &self.pool,
+            self.kb,
+            thing,
+            Some(self.location),
+            &json!({ "value": "desk" }),
+            Validity::default().attested(Some("2026-09-23T08:00:00Z".parse()?)),
+            1.0,
+        )
+        .await?;
+        utopia_store::graph::add_evidence(&self.pool, fact, chunk, None, Some("is on")).await?;
+        Ok((doc, thing, fact))
+    }
+
+    async fn call(&self, method: &str, uri: &str) -> anyhow::Result<(StatusCode, Value)> {
+        let response = self
+            .app
+            .clone()
+            .oneshot(
+                Request::builder()
+                    .method(method)
+                    .uri(uri)
+                    .header("Authorization", format!("Bearer {}", self.token))
+                    .body(Body::empty())?,
+            )
+            .await?;
+        let status = response.status();
+        let bytes = to_bytes(response.into_body(), 1 << 20).await?;
+        Ok((
+            status,
+            serde_json::from_slice(&bytes).unwrap_or(Value::Null),
+        ))
+    }
+
+    /// 这样东西此刻还挂着规则的结论吗
+    async fn concluded(&self, thing: Uuid) -> anyhow::Result<bool> {
+        let (n,): (i64,) = sqlx::query_as(
+            "SELECT count(*) FROM derived_facts WHERE subject_id = $1 AND invalidated_at IS NULL",
+        )
+        .bind(thing)
+        .fetch_one(&self.pool)
+        .await?;
+        Ok(n > 0)
+    }
+
+    async fn conclusion_ids(&self, thing: Uuid) -> anyhow::Result<Vec<Uuid>> {
+        Ok(sqlx::query_scalar(
+            "SELECT id FROM derived_facts WHERE subject_id = $1 AND invalidated_at IS NULL ORDER BY id",
+        )
+        .bind(thing)
+        .fetch_all(&self.pool)
+        .await?)
+    }
+
+    async fn cleanup(self) -> anyhow::Result<()> {
+        // 库先走：删除记录（document_deletions）随库级联，它记着删的人，人要留到最后
+        sqlx::query("DELETE FROM knowledge_bases WHERE id = $1")
+            .bind(self.kb)
+            .execute(&self.pool)
+            .await?;
+        sqlx::query("DELETE FROM organizations WHERE id = $1")
+            .bind(self.org)
+            .execute(&self.pool)
+            .await?;
+        self.pool.close().await;
+        Ok(())
+    }
+}
+
+#[tokio::test]
+async fn a_cleanup_retires_what_its_documents_concluded() -> anyhow::Result<()> {
+    let Some(f) = Fixture::new().await? else {
+        return Ok(());
+    };
+    let run = async {
+        let (deleted, by_delete, _) = f.reading("cup-1").await?;
+        let (_, by_cleanup, reading) = f.reading("cup-2").await?;
+        let (_, unrelated, _) = f.reading("cup-3").await?;
+        utopia_store::reasoning::materialize(&f.pool, f.kb).await?;
+        assert!(f.concluded(by_delete).await? && f.concluded(by_cleanup).await?);
+        let cleanup_before = f.conclusion_ids(by_cleanup).await?;
+        let unrelated_before = f.conclusion_ids(unrelated).await?;
+        assert_eq!(unrelated_before.len(), 1);
+
+        // 对照：删一篇，删完即按开关重推
+        let (status, body) = f
+            .call("DELETE", &format!("/api/v1/documents/{deleted}"))
+            .await?;
+        assert_eq!(status, StatusCode::OK, "{body}");
+        assert!(
+            !f.concluded(by_delete).await?,
+            "a single delete settles the derivations"
+        );
+        assert_eq!(f.conclusion_ids(by_cleanup).await?, cleanup_before);
+        assert_eq!(f.conclusion_ids(unrelated).await?, unrelated_before);
+
+        // 墓碑 + 清理：同一件事按批做
+        utopia_store::documents::mark_missing_keys(&f.pool, f.source, &["api:cup-2".into()])
+            .await?;
+        let (status, body) = f
+            .call(
+                "POST",
+                &format!("/api/v1/kbs/{}/sources/{}/missing/cleanup", f.kb, f.source),
+            )
+            .await?;
+        assert_eq!(status, StatusCode::OK, "{body}");
+        assert_eq!(body["deleted"], json!(1));
+        let (gone,): (bool,) =
+            sqlx::query_as("SELECT invalidated_at IS NOT NULL FROM facts WHERE id = $1")
+                .bind(reading)
+                .fetch_one(&f.pool)
+                .await?;
+        assert!(gone, "the reading's only evidence was deleted");
+        assert!(
+            !f.concluded(by_cleanup).await?,
+            "the conclusion that reading supported must be retired as after a single delete"
+        );
+        assert_eq!(
+            f.conclusion_ids(unrelated).await?,
+            unrelated_before,
+            "cleanup must preserve the pre-existing unrelated conclusion row"
+        );
+        anyhow::Ok(())
+    }
+    .await;
+    f.cleanup().await?;
+    run
+}
diff --git a/crates/utopia-server/src/api/sources_routes.rs b/crates/utopia-server/src/api/sources_routes.rs
index 105600cc0..fd2725c58 100644
--- a/crates/utopia-server/src/api/sources_routes.rs
+++ b/crates/utopia-server/src/api/sources_routes.rs
@@ -280,10 +280,19 @@ pub async fn cleanup_missing(
             .map_err(|e| utopia_core::AppError::Other(e.into()))?
             .map_err(utopia_core::AppError::Other)?;
     }
+    // 与单篇删除同一个收尾：前提没了，派生当场跟上，而不是挂到下一轮定时推导（#875）。
+    // 一批只推一遍
+    if !ids.is_empty() {
+        super::documents_routes::settle_derivations(&state, kb_id).await?;
+    }
     state.emit_source(kb_id);
     Ok(Json(json!({ "deleted": ids.len() })))
 }
 
+#[cfg(test)]
+#[path = "sources_cleanup_tests.rs"]
+mod cleanup_tests;
+
 pub async fn delete(
     State(state): State<AppState>,
     AuthUser(user): AuthUser,