diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 00000000..6eb442a1
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,11 @@
+{
+    "name": "Default Linux Universal",
+    "image": "mcr.microsoft.com/devcontainers/javascript-node:22",
+    "features": {
+        "ghcr.io/devcontainer-community/devcontainer-features/bun.sh:1": {}
+    },
+    "runArgs": [
+        "--memory=4g",
+        "--memory-swap=4g"
+    ]
+}
\ No newline at end of file
diff --git a/packages/app/src/components/prompt-input/history.test.ts b/packages/app/src/components/prompt-input/history.test.ts
index 94f24ce9..2159047d 100644
--- a/packages/app/src/components/prompt-input/history.test.ts
+++ b/packages/app/src/components/prompt-input/history.test.ts
@@ -41,6 +41,51 @@ describe("prompt-input history", () => {
     expect(dedupedComments).toBe(commentsOnly)
   })
 
+  const filePrompt = (path: string, selection?: { startLine: number; startChar: number; endLine: number; endChar: number }): Prompt => [
+    { type: "file", path, content: `@${path}`, start: 0, end: path.length + 1, selection },
+  ]
+  const agentPrompt = (name: string): Prompt => [{ type: "agent", name, content: `@${name}`, start: 0, end: name.length + 1 }]
+  const imagePrompt = (id: string): Prompt => [
+    { type: "image", id, filename: "img.png", mime: "image/png", blob: { id, url: `blob:${id}` } },
+  ]
+
+  test("prependHistoryEntry deduplicates file parts only when path and selection match", () => {
+    const selection = { startLine: 1, startChar: 0, endLine: 2, endChar: 3 }
+    const withFile = prependHistoryEntry([], filePrompt("src/a.ts", selection))
+    expect(withFile).toHaveLength(1)
+
+    const sameFile = prependHistoryEntry(withFile, filePrompt("src/a.ts", { ...selection }))
+    expect(sameFile).toBe(withFile)
+
+    const differentPath = prependHistoryEntry(withFile, filePrompt("src/b.ts", selection))
+    expect(differentPath).toHaveLength(2)
+
+    const differentSelection = prependHistoryEntry(withFile, filePrompt("src/a.ts", { ...selection, endChar: 9 }))
+    expect(differentSelection).toHaveLength(2)
+
+    const noSelection = prependHistoryEntry(withFile, filePrompt("src/a.ts", undefined))
+    expect(noSelection).toHaveLength(2)
+  })
+
+  test("prependHistoryEntry deduplicates agent and image parts by identity", () => {
+    const withAgent = prependHistoryEntry([], agentPrompt("reviewer"))
+    expect(prependHistoryEntry(withAgent, agentPrompt("reviewer"))).toBe(withAgent)
+    expect(prependHistoryEntry(withAgent, agentPrompt("other"))).toHaveLength(2)
+
+    const withImage = prependHistoryEntry([], imagePrompt("img-1"))
+    expect(prependHistoryEntry(withImage, imagePrompt("img-1"))).toBe(withImage)
+    expect(prependHistoryEntry(withImage, imagePrompt("img-2"))).toHaveLength(2)
+  })
+
+  test("prependHistoryEntry treats mismatched part types and comment fields as distinct entries", () => {
+    const withText = prependHistoryEntry([], text("hello"))
+    expect(prependHistoryEntry(withText, filePrompt("src/a.ts", undefined))).toHaveLength(2)
+
+    const withComment = prependHistoryEntry([], text("hello"), [comment("c1")])
+    const differentCommentText = prependHistoryEntry(withComment, text("hello"), [comment("c1", "different")])
+    expect(differentCommentText).toHaveLength(2)
+  })
+
   test("navigatePromptHistory restores saved prompt when moving down from newest", () => {
     const entries = [text("third"), text("second"), text("first")]
     const up = navigatePromptHistory({
diff --git a/packages/app/src/components/prompt-input/history.ts b/packages/app/src/components/prompt-input/history.ts
index 79e8abc0..3dff7910 100644
--- a/packages/app/src/components/prompt-input/history.ts
+++ b/packages/app/src/components/prompt-input/history.ts
@@ -112,39 +112,37 @@ function isCommentEqual(commentA: PromptHistoryComment, commentB: PromptHistoryC
   )
 }
 
+type PromptPart = Prompt[number]
+type FilePromptPart = Extract<PromptPart, { type: "file" }>
+
+function isFileSelectionEqual(a: FilePromptPart["selection"], b: FilePromptPart["selection"]) {
+  if (!a && !b) return true
+  if (!a || !b) return false
+  return a.startLine === b.startLine && a.startChar === b.startChar && a.endLine === b.endLine && a.endChar === b.endChar
+}
+
+const PART_COMPARATORS: Record<PromptPart["type"], (a: PromptPart, b: PromptPart) => boolean> = {
+  text: (a, b) => a.type === "text" && b.type === "text" && a.content === b.content,
+  file: (a, b) =>
+    a.type === "file" && b.type === "file" && a.path === b.path && isFileSelectionEqual(a.selection, b.selection),
+  agent: (a, b) => a.type === "agent" && b.type === "agent" && a.name === b.name,
+  image: (a, b) => a.type === "image" && b.type === "image" && a.id === b.id,
+}
+
+function arePromptPartsEqual(partA: PromptPart, partB: PromptPart): boolean {
+  if (partA.type !== partB.type) return false
+  return PART_COMPARATORS[partA.type](partA, partB)
+}
+
 function isPromptEqual(promptA: PromptHistoryStoredEntry, promptB: PromptHistoryStoredEntry) {
   const entryA = normalizePromptHistoryEntry(promptA)
   const entryB = normalizePromptHistoryEntry(promptB)
   if (entryA.prompt.length !== entryB.prompt.length) return false
-  for (let i = 0; i < entryA.prompt.length; i++) {
-    const partA = entryA.prompt[i]
-    const partB = entryB.prompt[i]
-    if (partA.type !== partB.type) return false
-    if (partA.type === "text" && partA.content !== (partB.type === "text" ? partB.content : "")) return false
-    if (partA.type === "file") {
-      if (partA.path !== (partB.type === "file" ? partB.path : "")) return false
-      const a = partA.selection
-      const b = partB.type === "file" ? partB.selection : undefined
-      const sameSelection =
-        (!a && !b) ||
-        (!!a &&
-          !!b &&
-          a.startLine === b.startLine &&
-          a.startChar === b.startChar &&
-          a.endLine === b.endLine &&
-          a.endChar === b.endChar)
-      if (!sameSelection) return false
-    }
-    if (partA.type === "agent" && partA.name !== (partB.type === "agent" ? partB.name : "")) return false
-    if (partA.type === "image" && partA.id !== (partB.type === "image" ? partB.id : "")) return false
-  }
   if (entryA.comments.length !== entryB.comments.length) return false
-  for (let i = 0; i < entryA.comments.length; i++) {
-    const commentA = entryA.comments[i]
-    const commentB = entryB.comments[i]
-    if (!commentA || !commentB || !isCommentEqual(commentA, commentB)) return false
-  }
-  return true
+  return (
+    entryA.prompt.every((part, i) => arePromptPartsEqual(part, entryB.prompt[i])) &&
+    entryA.comments.every((comment, i) => isCommentEqual(comment, entryB.comments[i]))
+  )
 }
 
 type HistoryNavInput = {