fix: show cumulative diff in Files Changed panel

packages/app/src/pages/session.tsx

@@ -1969,8 +1969,8 @@ export default function Page() {
           classes={{ button: compact ? "w-full !py-2" : "w-full" }}
           onClick={() => setStore("mobileTab", "changes")}
         >
-          {"Modified Files"}
-        </Tabs.Trigger>
+{"Files Changed"}
+</Tabs.Trigger>
       </Tabs.List>
     </Tabs>
   )

packages/app/src/pages/session/session-side-panel.tsx

@@ -595,7 +595,7 @@ export function SessionSidePanel(props: {
                                 aria-controls={activeTab() === "review" ? reviewTabPanelID : undefined}
                               >
                                 {props.hasReview()
-                                   ? "Modified Files"
+                                   ? "Files Changed"
                                    : language.t("session.tab.review")}
                               </Tabs.Trigger>
                             </Show>
@@ -818,7 +818,7 @@ export function SessionSidePanel(props: {
                             </>
                           }
                         >
-                          {"Modified Files"}
+                          {"Files Changed"}
                         </Show>
                       </Tabs.Trigger>
                       <Tabs.Trigger value="all" class="flex-1" classes={{ button: "w-full" }}>

packages/opencode/src/session/session.ts

@@ -843,7 +843,7 @@ const layer: Layer.Layer<
       // and the last step-finish snapshot hash (session-end ref)
       let from: string | undefined
       let lastStepFinish: string | undefined
-      // Collect all agent-touched files from PatchParts (absolute paths)
+      // Collect all agent-touched files from PatchParts and completed tool parts (absolute paths)
       const agentFilesAbsolute = new Set<string>()
 
       for (const msg of all) {
@@ -857,6 +857,14 @@ const layer: Layer.Layer<
           if (part.type === "patch" && part.files) {
             for (const file of part.files) agentFilesAbsolute.add(file)
           }
+          // In-flight file tracking: also collect files from completed tool parts with filediff metadata
+          if (part.type === "tool") {
+            const toolPart = part as { tool?: string; state?: { status?: string; metadata?: Record<string, unknown> } }
+            if (toolPart.state?.status === "completed") {
+              const filediff = toolPart.state?.metadata?.filediff as { file?: string } | undefined
+              if (filediff?.file) agentFilesAbsolute.add(filediff.file)
+            }
+          }
         }
       }
 
@@ -878,12 +886,28 @@ const layer: Layer.Layer<
           }
 
           const allDiffs = yield* snapshot.diffFull(from, to).pipe(
-            Effect.catchCause(() => Effect.succeed([] as Snapshot.FileDiff[])),
+            Effect.catchCause((cause) =>
+              Effect.gen(function* () {
+                yield* Effect.logWarning("diffFull failed, falling through to per-file fallback", { cause })
+                return [] as Snapshot.FileDiff[]
+              }),
+            ),
           )
           const filtered = allDiffs.filter(
             (d: Snapshot.FileDiff) => d.file && agentFiles.has(d.file) && (d.additions ?? 0) + (d.deletions ?? 0) > 0,
           )
           if (filtered.length > 0) return filtered
+
+          // Fallback A: primary returned empty but from hash exists — per-file git show vs current disk
+          const perFileDiffs = yield* snapshot.diffFromDisk(from, [...agentFiles]).pipe(
+            Effect.catchCause((cause) =>
+              Effect.gen(function* () {
+                yield* Effect.logWarning("diffFromDisk failed, falling through to summary fallback", { cause })
+                return [] as Snapshot.FileDiff[]
+              }),
+            ),
+          )
+          if (perFileDiffs.length > 0) return perFileDiffs
         }
       }
 

packages/opencode/src/snapshot/index.ts

@@ -42,6 +42,7 @@ export interface Interface {
   readonly revert: (patches: Patch[]) => Effect.Effect<void>
   readonly diff: (hash: string) => Effect.Effect<string>
   readonly diffFull: (from: string, to: string) => Effect.Effect<FileDiff[]>
+  readonly diffFromDisk: (ref: string, files: string[]) => Effect.Effect<FileDiff[]>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/Snapshot") {}
@@ -758,14 +759,56 @@ const layer: Layer.Layer<Service, never, FSUtil.Service | AppProcess.Service | C
           )
         })
 
+        const diffFromDisk = Effect.fnUntraced(function* (ref: string, files: string[]) {
+          return yield* locked(
+            Effect.gen(function* () {
+              const result: FileDiff[] = []
+              const patchFn = (file: string, before: string, after: string) =>
+                formatPatch(structuredPatch(file, file, before, after, "", "", { context: Number.MAX_SAFE_INTEGER }))
+
+              for (const file of files) {
+                const beforeResult = yield* git([...cfg, ...args(["show", `${ref}:${file}`])])
+                const before = beforeResult.code === 0 ? beforeResult.text : ""
+
+                const diskPath = path.join(state.worktree, file)
+                const after = yield* read(diskPath)
+
+                if (before === after) continue
+
+                // Compute actual line-level additions/deletions from the structured patch
+                const sp = structuredPatch(file, file, before, after, "", "")
+                let adds = 0
+                let dels = 0
+                for (const hunk of sp.hunks) {
+                  for (const line of hunk.lines) {
+                    if (line.startsWith("+")) adds++
+                    else if (line.startsWith("-")) dels++
+                  }
+                }
+
+                const status: "added" | "deleted" | "modified" = before === "" ? "added" : after === "" ? "deleted" : "modified"
+                result.push({
+                  file,
+                  patch: patchFn(file, before, after),
+                  additions: adds,
+                  deletions: dels,
+                  status,
+                })
+              }
+
+              return result
+            }),
+          )
+        })
+
         yield* cleanup().pipe(
           Effect.catchCause((cause) => Effect.logError("cleanup loop failed", { cause: Cause.pretty(cause) })),
           Effect.repeat(Schedule.spaced(Duration.hours(1))),
           Effect.delay(Duration.minutes(1)),
           Effect.forkScoped,
         )
 
-        return { cleanup, track, patch, restore, revert, diff, diffFull }
+        return { cleanup, track, patch, restore, revert, diff, diffFull, diffFromDisk }
       }),
     )
 
@@ -794,6 +837,9 @@ const layer: Layer.Layer<Service, never, FSUtil.Service | AppProcess.Service | C
       diffFull: Effect.fn("Snapshot.diffFull")(function* (from: string, to: string) {
         return yield* InstanceState.useEffect(state, (s) => s.diffFull(from, to))
       }),
+      diffFromDisk: Effect.fn("Snapshot.diffFromDisk")(function* (ref: string, files: string[]) {
+        return yield* InstanceState.useEffect(state, (s) => s.diffFromDisk(ref, files))
+      }),
     })
   }),
 )

packages/tui/src/feature-plugins/sidebar/files.tsx

@@ -24,7 +24,7 @@ function View(props: { api: TuiPluginApi; session_id: string }) {
             <text fg={theme().text}>{open() ? "▼" : "▶"}</text>
           </Show>
           <text fg={theme().text}>
-            <b>Modified Files</b>
+            <b>Files Changed</b>
           </text>
         </box>
         <Show when={list().length <= 2 || open()}>

packages/ui/src/i18n/en.ts

@@ -30,7 +30,7 @@ export const dict: Record<string, string> = {
   "ui.sessionReviewV2.empty.noGit.action": "Create Git repository",
   "ui.sessionReviewV2.empty.noGit.actionLoading": "Creating Git repository...",
   "ui.sessionReviewV2.empty.changes.title": "No file changes yet",
-  "ui.sessionReviewV2.empty.changes.description": "Project changes will appear here",
+  "ui.sessionReviewV2.empty.changes.description": "File changes from current session will appear here",
 
   "ui.sessionReview.openFile": "Open file",
   "ui.sessionReview.selection.line": "line {{line}}",