From 5580f2f1e90bfd6401707b9ed6b9d31640186e53 Mon Sep 17 00:00:00 2001
From: jm-clius <hanno@status.im>
Date: Thu, 23 Oct 2025 14:36:48 +0100
Subject: [PATCH] fix: more buffer fixes

---
 .../message_channel/repair/buffers.spec.ts    | 28 +++++++++++++------
 .../sds/src/message_channel/repair/buffers.ts |  6 ++--
 .../sds/src/message_channel/repair/repair.ts  | 17 +++++++++++
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/packages/sds/src/message_channel/repair/buffers.spec.ts b/packages/sds/src/message_channel/repair/buffers.spec.ts
index 972c64d73f..484d6118cf 100644
--- a/packages/sds/src/message_channel/repair/buffers.spec.ts
+++ b/packages/sds/src/message_channel/repair/buffers.spec.ts
@@ -38,7 +38,7 @@ describe("OutgoingRepairBuffer", () => {
     expect(items[0].tReq).to.equal(1000); // Should keep original
   });
 
-  it("should evict oldest entry when buffer is full", () => {
+  it("should evict furthest entry when buffer is full", () => {
     const entry1: HistoryEntry = { messageId: "msg1" };
     const entry2: HistoryEntry = { messageId: "msg2" };
     const entry3: HistoryEntry = { messageId: "msg3" };
@@ -47,13 +47,13 @@ describe("OutgoingRepairBuffer", () => {
     buffer.add(entry2, 2000);
     buffer.add(entry1, 1000);
     buffer.add(entry3, 3000);
-    buffer.add(entry4, 1500); // Should evict msg1 (oldest T_req)
+    buffer.add(entry4, 1500); // Should evict msg3 (furthest T_req = 3000)
 
     const items = buffer.getItems();
     expect(items).to.have.lengthOf(3);
-    expect(buffer.has("msg1")).to.be.false; // msg1 should be evicted
+    expect(buffer.has("msg3")).to.be.false; // msg3 should be evicted (furthest T_req)
+    expect(buffer.has("msg1")).to.be.true;
     expect(buffer.has("msg2")).to.be.true;
-    expect(buffer.has("msg3")).to.be.true;
     expect(buffer.has("msg4")).to.be.true;
   });
 
@@ -69,11 +69,23 @@ describe("OutgoingRepairBuffer", () => {
     const eligible = buffer.getEligible(1500, 3);
     expect(eligible).to.have.lengthOf(1);
     expect(eligible[0].messageId).to.equal("msg1");
+  });
 
-    const eligible2 = buffer.getEligible(2500, 3);
-    expect(eligible2).to.have.lengthOf(2);
-    expect(eligible2[0].messageId).to.equal("msg1");
-    expect(eligible2[1].messageId).to.equal("msg2");
+  it("should get multiple eligible entries at later time", () => {
+    const entry1: HistoryEntry = { messageId: "msg1" };
+    const entry2: HistoryEntry = { messageId: "msg2" };
+    const entry3: HistoryEntry = { messageId: "msg3" };
+
+    // Create new buffer for second test since getEligible marks entries as requested
+    const buffer2 = new OutgoingRepairBuffer(3);
+    buffer2.add(entry1, 1000);
+    buffer2.add(entry2, 2000);
+    buffer2.add(entry3, 3000);
+
+    const eligible = buffer2.getEligible(2500, 3);
+    expect(eligible).to.have.lengthOf(2);
+    expect(eligible[0].messageId).to.equal("msg1");
+    expect(eligible[1].messageId).to.equal("msg2");
   });
 
   it("should respect maxRequests limit", () => {
diff --git a/packages/sds/src/message_channel/repair/buffers.ts b/packages/sds/src/message_channel/repair/buffers.ts
index 8f405961d7..9d48c61baf 100644
--- a/packages/sds/src/message_channel/repair/buffers.ts
+++ b/packages/sds/src/message_channel/repair/buffers.ts
@@ -55,10 +55,10 @@ export class OutgoingRepairBuffer {
 
     // Check buffer size limit
     if (this.items.length >= this.maxSize) {
-      // Evict oldest T_req entry (first in sorted array since we want to evict oldest)
-      const evicted = this.items.shift()!;
+      // Evict furthest T_req entry (last in sorted array) to preserve most urgent repairs
+      const evicted = this.items.pop()!;
       log.warn(
-        `Buffer full, evicted oldest entry ${evicted.entry.messageId} with T_req ${evicted.tReq}`
+        `Buffer full, evicted furthest entry ${evicted.entry.messageId} with T_req ${evicted.tReq}`
       );
     }
 
diff --git a/packages/sds/src/message_channel/repair/repair.ts b/packages/sds/src/message_channel/repair/repair.ts
index 79e1e69770..e833015213 100644
--- a/packages/sds/src/message_channel/repair/repair.ts
+++ b/packages/sds/src/message_channel/repair/repair.ts
@@ -315,6 +315,23 @@ export class RepairManager {
    * Update number of response groups (e.g., when participants change)
    */
   public updateResponseGroups(numParticipants: number): void {
+    if (
+      numParticipants < 0 ||
+      !Number.isFinite(numParticipants) ||
+      !Number.isInteger(numParticipants)
+    ) {
+      throw new Error(
+        `Invalid numParticipants: ${numParticipants}. Must be a non-negative integer.`
+      );
+    }
+
+    if (numParticipants > Number.MAX_SAFE_INTEGER) {
+      log.warn(
+        `numParticipants ${numParticipants} exceeds MAX_SAFE_INTEGER, using MAX_SAFE_INTEGER`
+      );
+      numParticipants = Number.MAX_SAFE_INTEGER;
+    }
+
     // Per spec: num_response_groups = max(1, num_participants / 128)
     this.config.numResponseGroups = Math.max(
       1,