diff --git a/docs/electron-observation.md b/docs/electron-observation.md
index 63e1fcdc79..2ebfcc5025 100644
--- a/docs/electron-observation.md
+++ b/docs/electron-observation.md
@@ -182,6 +182,15 @@ If cleanup cannot be verified, the error retains collected observations in
 `details.partial_observation` and marks their application cleanup `unverified`.
 Cleanup uncertainty does not authorize signaling unrelated processes.
 
+On Linux, Chromium-based processes can overwrite the initial environment memory
+exposed through `/proc/<pid>/environ`. The environment may be readable while
+`REA_PROCESS_RUN_ID` is absent, even if the application still sees it through
+`process.env`. REA reports the missing marker and leaves lineage ownership and
+cleanup unverified; the PID, executable, or parent relationship cannot replace
+that ownership proof. This limitation can affect owned Electron captures on
+native Linux as well as WSL. It does not establish that all Electron versions or
+Linux environments behave the same way.
+
 Main-process IPC recording keeps original-function removal for `on` and `once`
 registrations and records a fired `once` callback once. Native Node.js owns
 `once` registration, firing and callable dispatch as well as removal order and
diff --git a/src/process/ProcessOwnership.lineage.test.ts b/src/process/ProcessOwnership.lineage.test.ts
index ba13724062..5a07a0f88c 100644
--- a/src/process/ProcessOwnership.lineage.test.ts
+++ b/src/process/ProcessOwnership.lineage.test.ts
@@ -43,6 +43,52 @@ const nativeIdentity = (
   },
 });
 
+it.each(
+  [false, true].flatMap((native) =>
+    ([undefined, "foreign"] as const).map((runId) => ({ native, runId })),
+  ),
+)(
+  "keeps missing ownership distinct from an observed foreign token, native=$native, runId=$runId",
+  async ({ native, runId }) => {
+    const signalGroup = vi.fn();
+    const host: ProcessOwnershipHost = {
+      platform: "linux",
+      listProcesses: async () => [launcher],
+      environment: async () =>
+        runId === undefined ? {} : { REA_PROCESS_RUN_ID: runId },
+      ...(native
+        ? {
+            processIdentities: async (rows: readonly ProcessTableEntry[]) =>
+              new Map(rows.map((row) => [row.pid, nativeIdentity(row)])),
+          }
+        : {}),
+      signalGroup,
+    };
+    const ownership = {
+      runId: "owned",
+      leaderPid: launcher.pid,
+      processGroupId: launcher.processGroupId,
+      expectedParentPid: launcher.parentPid,
+      expectedCommand: launcher.command,
+    };
+    await expect(
+      observeOwnedProcessLineage(ownership, host),
+    ).resolves.toMatchObject({
+      status: "unavailable",
+      reason:
+        runId === undefined
+          ? "REA_PROCESS_RUN_ID was absent from the readable environment for PID 100; process lineage ownership remains unverified"
+          : "process lineage contains an unowned or PID-reused process",
+    });
+    await expect(
+      cleanupOwnedProcessGroup(ownership, host),
+    ).resolves.toMatchObject({
+      cleaned: false,
+    });
+    expect(signalGroup).not.toHaveBeenCalled();
+  },
+);
+
 it.each(
   (["parent", "group", "command"] as const).flatMap((mismatch) =>
     (
diff --git a/src/process/ProcessOwnershipObservation.ts b/src/process/ProcessOwnershipObservation.ts
index 11aac8dee2..d3b43c36c9 100644
--- a/src/process/ProcessOwnershipObservation.ts
+++ b/src/process/ProcessOwnershipObservation.ts
@@ -275,7 +275,7 @@ export const observeOwnedProcessLineage = async (
       if (observation.runId !== ownership.runId)
         return unavailableLineage(
           ownership,
-          "process lineage contains an unowned or PID-reused process",
+          lineageTokenMismatchReason(member.pid, observation.runId),
         );
       if (member.pid !== launcher.pid) verifiedDescendants.push(member);
       const seeded = examinedRefresh.get(member.pid);
@@ -476,7 +476,7 @@ const observeNativeOwnedProcessLineage = async (
     if (fact.token.runId !== ownership.runId)
       return unavailableLineage(
         ownership,
-        "process lineage contains an unowned or PID-reused process",
+        lineageTokenMismatchReason(member.pid, fact.token.runId),
       );
     const nativeMember = processWithNativeRelation(
       fact.process,
@@ -585,7 +585,7 @@ const classifyIdentitylessLineageRefresh = async (
     if (observation.runId !== ownership.runId)
       return {
         status: "unavailable",
-        reason: "process lineage contains an unowned or PID-reused process",
+        reason: lineageTokenMismatchReason(launcherPid, observation.runId),
       };
   }
   const identityFailure = launcherIdentityFailure(refreshedLauncher, ownership);
@@ -621,7 +621,7 @@ const classifyIdentitylessLineageRefresh = async (
         if (inTree.has(process.pid))
           return {
             status: "unavailable",
-            reason: "process lineage contains an unowned or PID-reused process",
+            reason: lineageTokenMismatchReason(process.pid, observation.runId),
           };
         continue;
       }
@@ -679,6 +679,14 @@ const processWithNativeRelation = (
       }
     : undefined;
 
+const lineageTokenMismatchReason = (
+  pid: number,
+  observedRunId: string | undefined,
+): string =>
+  observedRunId === undefined
+    ? `REA_PROCESS_RUN_ID was absent from the readable environment for PID ${String(pid)}; process lineage ownership remains unverified`
+    : "process lineage contains an unowned or PID-reused process";
+
 const unavailableLineage = (
   ownership: OwnedProcessGroup,
   reason: string,