huhamhire · Jul 27, 2026 · Jul 27, 2026 · Jul 27, 2026
@@ -120,7 +120,13 @@ export async function runPlanning(
     deps.stateStore,
     pr.localId,
     // When a Diff selection reference is present, persist it alongside, for the UI to show the "referenced code" collapsed below the bubble.
-    { role: 'user', content: userRequest, referencedContext: deps.referencedContext },
+    // headSha stamps the PR head this turn was made against, so a later turn on a newer commit gets a "code changed" marker in the planning context.
+    {
+      role: 'user',
+      content: userRequest,
+      referencedContext: deps.referencedContext,
+      headSha: pr.sourceRef.sha,
+    },
     now,
   );
 
@@ -161,6 +167,8 @@ export async function runPlanning(
         summarySections: buildSummarySections(),
         userRequest,
         history,
+        // Current PR head, so the planning context can flag a code change since the newest historical turn.
+        currentHeadSha: pr.sourceRef.sha,
         referencedContext: deps.referencedContext,
         maxSteps: deps.maxSteps,
         maxFollowupAsks: deps.maxFollowupAsks,
@@ -172,7 +180,12 @@ export async function runPlanning(
       await appendAgentMessage(
         deps.stateStore,
         pr.localId,
-        { role: 'assistant', content: result.finalText, recommendation: result.recommendation },
+        {
+          role: 'assistant',
+          content: result.finalText,
+          recommendation: result.recommendation,
+          headSha: pr.sourceRef.sha,
+        },
         now,
       );
     }

@@ -265,6 +265,8 @@ export class RunExecutor {
       origin: item.priority,
       // Single-commit review scope persisted with the run: the result card uses it to show a scope badge.
       scope: req.scope,
+      // PR head commit the run runs against: stamped so ChatPane can draw a commit divider when the code changes between runs.
+      headSha: pr.sourceRef.sha,
     });
     // Upgrade the info (startedAt=null at enqueue) to active form + broadcast (via the scheduling layer).
     item.info = { ...item.info, startedAt: run.startedAt };

@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react';
+import { useEffect, useMemo, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import type {
   Finding,
@@ -24,6 +24,7 @@ import { useChatActions } from './hooks/useChatActions';
 import { useChatTimeline } from './hooks/useChatTimeline';
 import { AgentStepRow, ThinkingLive } from './components/AgentStep';
 import { ChatEmpty } from './components/ChatEmpty';
+import { CommitDivider } from './components/CommitDivider';
 import { ChatInputBar } from './components/ChatInputBar';
 import { ConversationMessage } from './components/ConversationMessage';
 import { PlanPanel } from './components/PlanPanel';
@@ -241,12 +242,31 @@ export function ChatPane({
     prLocalId,
   });
 
+  // Commit divider: the PR head SHA the most recent completed run reviewed. When the current PR head has advanced past
+  // it, a single sawtooth divider is shown at the bottom of the timeline marking the new head — signalling prior
+  // reviews are now stale, even if no run has been started against the new code yet. Suppressed while a run is active
+  // (it's already processing the current head). Returns the new head SHA to mark, or null when nothing is stale.
+  const staleHeadSha = useMemo(() => {
+    if (hasMyActive) return null;
+    const head = pr?.sourceRef.sha;
+    if (!head) return null;
+    // Timeline is ascending, so the last run entry carrying a headSha is the most recent completed review.
+    let lastRunHeadSha: string | undefined;
+    for (const entry of timeline) {
+      if (entry.run?.headSha) lastRunHeadSha = entry.run.headSha;
+    }
+    // No baseline run with a recorded head (e.g. only pre-feature runs) → nothing to be stale against.
+    if (!lastRunHeadSha) return null;
+    return head !== lastRunHeadSha ? head : null;
+  }, [timeline, hasMyActive, pr?.sourceRef.sha]);
+
   // Pure UI state: rule preview modal / clear confirm modal / merge confirm modal
   const [showRulePreview, setShowRulePreview] = useState(false);
   const [showClearConfirm, setShowClearConfirm] = useState(false);
   const [showMergeConfirm, setShowMergeConfirm] = useState(false);
 
-  const { runs, error, loadingSession, matchedRules, bodyRef, hasMoreOlder, loadingOlder } = session;
+  const { runs, error, loadingSession, matchedRules, bodyRef, hasMoreOlder, loadingOlder } =
+    session;
 
   // Re-review card ↔ original finding card cross-link: scroll to and briefly highlight. The flash class differs by target: run cards use chat-run-flash
   // (fading background, visible on the run card's transparent base); finding cards use chat-finding-flash (an overlay highlight ring — finding cards have
@@ -396,6 +416,9 @@ export function ChatPane({
             <ConversationMessage key={entry.key} message={entry.message} />
           ) : null,
         )}
+        {/* Commit divider: the PR head advanced past the last reviewed commit → mark the new head at the bottom of the
+            run list (prior reviews are stale). Shown even when no run has been started against the new code yet. */}
+        {staleHeadSha && <CommitDivider sha={staleHeadSha} />}
         {/* This PR's queued tasks: placed after running ones, each cancellable individually. The position uses the **global** queue order (the queue is shared across PRs,
             otherwise every PR showing "position 1" would be misleading) — the runId's index in the global waiting array +1. */}
         {myWaiting.map((w) => (

@@ -0,0 +1,28 @@
+import { useTranslation } from 'react-i18next';
+import { CommitIcon } from '../../../common';
+
+/**
+ * Sawtooth "commit divider" shown at the bottom of the run timeline when the PR head has advanced past the commit the
+ * most recent run reviewed (see ChatPane staleHeadSha). It marks the new head — signalling that the reviews above are
+ * now based on stale code — even if no run has been started against the new commit yet. The label is the abbreviated
+ * commit id (the full SHA is in the tooltip), reusing the same chip vocabulary as the single-commit scope badge in
+ * RunResultView.
+ */
+export function CommitDivider({ sha }: { sha: string }) {
+  const { t } = useTranslation();
+  const short = sha.slice(0, 8);
+  const title = t('chatPane.commitDividerTitle', { sha });
+  return (
+    <div className="chat-commit-divider" role="separator" aria-label={title}>
+      <span className="chat-commit-divider__line" aria-hidden="true" />
+      <span
+        className="chat-chip chat-chip-quiet chat-chip-neutral chat-commit-divider__chip"
+        title={title}
+      >
+        <CommitIcon size={12} />
+        {short}
+      </span>
+      <span className="chat-commit-divider__line" aria-hidden="true" />
+    </div>
+  );
+}
@@ -71,6 +71,7 @@
     "codeExistingAria": "Originalcode",
     "codeImprovedAria": "Verbesserter Code",
     "commandNoArgs": "{{cmd}} akzeptiert keine Argumente",
+    "commitDividerTitle": "Code seit der letzten Review geändert — jetzt bei Commit {{sha}}",
     "deleteRunAria": "Löschen",
     "deleteRunTitle": "Diesen Lauf löschen",
     "draftJumpEditTitle": "Im Code bearbeiten",

@@ -71,6 +71,7 @@
     "codeExistingAria": "Original code",
     "codeImprovedAria": "Improved code",
     "commandNoArgs": "{{cmd}} does not accept arguments",
+    "commitDividerTitle": "Code changed since the last review — now at commit {{sha}}",
     "deleteRunAria": "Delete",
     "deleteRunTitle": "Delete this run",
     "draftJumpEditTitle": "Edit in code",

@@ -71,6 +71,7 @@
     "codeExistingAria": "元のコード",
     "codeImprovedAria": "改善後のコード",
     "commandNoArgs": "{{cmd}} は引数を受け付けません",
+    "commitDividerTitle": "前回のレビュー以降にコードが変更されました — 現在はコミット {{sha}}",
     "deleteRunAria": "削除",
     "deleteRunTitle": "この記録を削除",
     "draftJumpEditTitle": "コード内で編集",

@@ -71,6 +71,7 @@
     "codeExistingAria": "原代码",
     "codeImprovedAria": "改进代码",
     "commandNoArgs": "{{cmd}} 不接受参数",
+    "commitDividerTitle": "自上次评审后代码已变更 —— 当前为提交 {{sha}}",
     "deleteRunAria": "删除",
     "deleteRunTitle": "删除此记录",
     "draftJumpEditTitle": "在代码中编辑",

@@ -102,6 +102,33 @@
   border-bottom: 1px dashed $border-muted;
 }
 
+// "Commit divider": a sawtooth rule inserted into the run timeline where the PR code changed between two runs (see
+// ChatPane commitDividers). A zigzag line flanks a centered commit-id chip, marking the newer commit the runs below it
+// ran against, so history runs on an older revision read as a separate section. The zigzag is a masked SVG tile, so its
+// color follows the theme token ($border-muted) via background-color and it renders correctly in both light and dark.
+$commit-zigzag: url("data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='12'%20height='8'%20viewBox='0%200%2012%208'%3E%3Cpath%20d='M0%206%20L3%202%20L6%206%20L9%202%20L12%206'%20fill='none'%20stroke='black'%20stroke-width='1.4'%20stroke-linejoin='round'/%3E%3C/svg%3E");
+.chat-commit-divider {
+  display: flex;
+  align-items: center;
+  gap: $space-3;
+  margin: $space-6 $space-2 $space-3;
+  user-select: none;
+
+  &__line {
+    flex: 1 1 auto;
+    height: 8px;
+    background-color: $border-muted;
+    opacity: 0.75;
+    -webkit-mask: $commit-zigzag repeat-x center / auto 100%;
+    mask: $commit-zigzag repeat-x center / auto 100%;
+  }
+
+  // Keep the commit-id chip at its intrinsic width; only the flanking zigzag lines flex.
+  &__chip {
+    flex: 0 0 auto;
+  }
+}
+
 // Rule chip matched by the current PR: a row below the actions bar, clicking pops up a body preview
 .chat-rule-chip {
   display: flex;

@@ -8,7 +8,11 @@ import type {
 } from '@meebox/shared';
 import { assembleSystemContext, type AssemblePrMeta } from './prompts.js';
 import type { MemoryNote } from './memory.js';
-import { DEFAULT_STEP_LABELS, DEFAULT_SUMMARY_SECTIONS, type AgentStepLabels } from './orchestrator.js';
+import {
+  DEFAULT_STEP_LABELS,
+  DEFAULT_SUMMARY_SECTIONS,
+  type AgentStepLabels,
+} from './orchestrator.js';
 import { createStepRecorder } from './steps/context.js';
 import {
   buildConversationContext,
@@ -69,6 +73,12 @@ export interface PlanningInput {
    * agent remembers earlier exchanges across rounds; **never** passed through to pr-agent tools (tools only see PR + this round's question).
    */
   history?: AgentMessage[];
+  /**
+   * Current PR head commit SHA. When it differs from the newest historical message's headSha (or between historical
+   * turns), buildConversationContext injects a "code changed to commit X" marker so the agent knows earlier discussion
+   * may reference outdated code. Context awareness only — never passed through to pr-agent tools.
+   */
+  currentHeadSha?: string;
   /**
    * Code reference selected by the user in the diff (self-describing block). Injected into this round's planning context so the agent knows which code the user is looking at;
    * **never** passed through to pr-agent tools (same constraint as history). Omitted = no selection reference this round.
@@ -130,7 +140,7 @@ export async function runPlanningAgent(
 
   // Inject prior multi-turn conversation into the planning context (trimmed by budget) so the agent remembers exchanges across rounds; only for the planning LLM's reference,
   // never passed through to pr-agent tools.
-  const convo = buildConversationContext(input.history ?? []);
+  const convo = buildConversationContext(input.history ?? [], input.currentHeadSha);
   const ctx: PlanStepCtx = {
     deps,
     input,
@@ -149,7 +159,13 @@ export async function runPlanningAgent(
   for (let i = 0; i < maxSteps; i++) {
     const outcome = await planCycleStep.run(ctx);
     if (outcome.kind === 'aborted') {
-      return { steps: rec.steps, finalText: '', tokenUsage: rec.usage, memories, terminationReason: 'aborted' };
+      return {
+        steps: rec.steps,
+        finalText: '',
+        tokenUsage: rec.usage,
+        memories,
+        terminationReason: 'aborted',
+      };
     }
     if (outcome.kind === 'final') {
       return {
@@ -162,5 +178,11 @@ export async function runPlanningAgent(
     }
   }
 
-  return { steps: rec.steps, finalText: '', tokenUsage: rec.usage, memories, terminationReason: 'max_steps' };
+  return {
+    steps: rec.steps,
+    finalText: '',
+    tokenUsage: rec.usage,
+    memories,
+    terminationReason: 'max_steps',
+  };
 }
@@ -105,18 +105,49 @@ export function normalizePlan(raw: PlannerAction['plan']): AgentTodoItem[] {
   return out;
 }
 
-/** Take the most recent rounds, each length-capped, and trim newest-to-oldest by total budget (drop earlier over-budget messages), returning text in ascending time order. */
-export function buildConversationContext(history: readonly AgentMessage[]): string {
-  const lines: string[] = [];
+/** Boundary marker injected into the conversation context where the PR head commit changed, so the planning agent knows
+ * messages above it were made against older code (soft awareness — no history is dropped). Internal prompt artifact → English. */
+function commitChangeMarker(sha: string): string {
+  return `[--- PR code updated to commit ${sha.slice(0, 8)} at this point; messages below are based on the new code, earlier ones may reference outdated code ---]`;
+}
+
+/**
+ * Take the most recent rounds, each length-capped, and trim newest-to-oldest by total budget (drop earlier over-budget
+ * messages), returning text in ascending time order. Where a message's `headSha` differs from the previous kept
+ * message's, a {@link commitChangeMarker} is interleaved so the agent perceives the code changed between those turns;
+ * a trailing marker is added when `currentHeadSha` (this turn's head) has advanced past the newest kept message.
+ * Messages without a recorded headSha (predating the field) never produce a marker.
+ */
+export function buildConversationContext(
+  history: readonly AgentMessage[],
+  currentHeadSha?: string,
+): string {
+  // First pass, newest→oldest: keep the messages that fit the budget.
+  const kept: AgentMessage[] = [];
   let budget = HISTORY_BUDGET_CHARS;
   for (let i = history.length - 1; i >= 0; i--) {
     const m = history[i]!;
     const line = `${m.role === 'user' ? 'User' : 'Assistant'}: ${clamp(m.content, HISTORY_MESSAGE_MAX)}`;
     if (line.length + 1 > budget) break; // budget exhausted: trim the earlier conversation entirely
     budget -= line.length + 1;
-    lines.push(line);
+    kept.push(m);
+  }
+  kept.reverse(); // ascending time order
+  // Second pass, ascending: render each message, inserting a commit-change marker at head-commit boundaries.
+  const lines: string[] = [];
+  let prevSha: string | undefined;
+  for (const m of kept) {
+    if (m.headSha && prevSha && m.headSha !== prevSha) lines.push(commitChangeMarker(m.headSha));
+    if (m.headSha) prevSha = m.headSha;
+    lines.push(
+      `${m.role === 'user' ? 'User' : 'Assistant'}: ${clamp(m.content, HISTORY_MESSAGE_MAX)}`,
+    );
+  }
+  // Trailing marker: the current turn's code has advanced past the newest historical message.
+  if (currentHeadSha && prevSha && currentHeadSha !== prevSha) {
+    lines.push(commitChangeMarker(currentHeadSha));
   }
-  return lines.reverse().join('\n');
+  return lines.join('\n');
 }
 
 /** Planning ReAct protocol: body is externalized in resources/prompts/protocol.md, the three section titles (localized per language) are injected via placeholders. */

@@ -61,6 +61,8 @@ export interface StartReviewRunInput {
   origin?: ReviewRun['origin'];
   /** Single-commit review scope (parent..sha); omitted = full PR scope. Persisted for the result card's scope badge. */
   scope?: ReviewRun['scope'];
+  /** PR head commit SHA the run runs against (pr.sourceRef.sha); persisted so ChatPane can draw a commit divider between runs across a code change. */
+  headSha?: string;
 }
 
 /** Write the initial running state; callers must start before invoking pr-agent. */
@@ -81,6 +83,7 @@ export async function startReviewRun(
     referencedFinding: input.referencedFinding,
     origin: input.origin,
     scope: input.scope,
+    headSha: input.headSha,
     status: 'running',
     startedAt: at.toISOString(),
   };

@@ -82,6 +82,13 @@ export interface AgentMessage {
    * not set when there is no selection / for assistant messages. (Finding references go through the /ask run card, not this field.)
    */
   referencedContext?: string;
+  /**
+   * PR head commit SHA (`pr.sourceRef.sha`) at the time this turn was recorded. Used by the planning agent's context
+   * assembly (buildConversationContext) to inject a "code changed to commit X" marker between turns whose head differs,
+   * so the agent perceives that earlier discussion may reference outdated code — without dropping any history. Messages
+   * predating this field are undefined and simply produce no marker.
+   */
+  headSha?: string;
   /** Creation time (ISO), used for timeline ordering. */
   at: string;
 }

@@ -314,6 +314,13 @@ export interface ReviewRun {
    * Default = whole-PR scope. The result card shows a scope badge accordingly.
    */
   scope?: ReviewRunCommitScope;
+  /**
+   * PR head commit SHA (`pr.sourceRef.sha`) the run was executed against, stamped at start. Used only for the ChatPane
+   * "commit divider": when two consecutive runs have differing headSha, the code changed between them, and a sawtooth
+   * divider marking the newer commit is inserted between the older (history) runs and the newer ones. Historical runs
+   * predating this field are undefined → no divider is drawn for them (compared only between two defined, differing SHAs).
+   */
+  headSha?: string;
   /** The pr-agent version obtained at probe time (CLI first line / the pr-agent version found by the embedded runtime) */
   prAgentVersion: string;
   strategy: PrAgentStrategy;