diff --git a/.github/size-check/.gitignore b/.github/size-check/.gitignore
new file mode 100644
index 000000000..54de99d36
--- /dev/null
+++ b/.github/size-check/.gitignore
@@ -0,0 +1,4 @@
+# Generated by xcodegen at run time.
+SizeCheck.xcodeproj/
+EmptyApp/Info.plist
+LiveKitApp/Info.plist
diff --git a/.github/size-check/EmptyApp/App.swift b/.github/size-check/EmptyApp/App.swift
new file mode 100644
index 000000000..8a81a742f
--- /dev/null
+++ b/.github/size-check/EmptyApp/App.swift
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2026 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import SwiftUI
+
+@main
+struct EmptyApp: App {
+    var body: some Scene {
+        WindowGroup {
+            Text("Hello, World!")
+        }
+    }
+}
diff --git a/.github/size-check/LiveKitApp/App.swift b/.github/size-check/LiveKitApp/App.swift
new file mode 100644
index 000000000..47f4244e5
--- /dev/null
+++ b/.github/size-check/LiveKitApp/App.swift
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2026 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import LiveKit
+import SwiftUI
+
+// Exercises a representative slice of the public API (connect + publish camera/mic
+// + a video view) so the linker keeps the main code paths.
+@MainActor
+final class CallModel: ObservableObject, RoomDelegate {
+    let room = Room()
+
+    init() {
+        room.add(delegate: self)
+    }
+
+    func connect() async {
+        do {
+            try await room.connect(url: "wss://example.livekit.cloud", token: "dev-token")
+            try await room.localParticipant.setCamera(enabled: true)
+            try await room.localParticipant.setMicrophone(enabled: true)
+        } catch {
+            print("Failed to connect: \(error)")
+        }
+    }
+
+    nonisolated func room(
+        _: Room,
+        participant _: LocalParticipant,
+        didPublishTrack publication: LocalTrackPublication,
+    ) {
+        guard publication.track is VideoTrack else { return }
+        print("Published a video track")
+    }
+}
+
+@main
+struct LiveKitApp: App {
+    @StateObject private var model = CallModel()
+
+    var body: some Scene {
+        WindowGroup {
+            VStack {
+                Text("LiveKit Hello World")
+                if let track = model.room.localParticipant.localVideoTracks.first?.track as? VideoTrack {
+                    SwiftUIVideoView(track)
+                }
+            }
+            .task { await model.connect() }
+        }
+    }
+}
diff --git a/.github/size-check/project.yml b/.github/size-check/project.yml
new file mode 100644
index 000000000..cf4023d64
--- /dev/null
+++ b/.github/size-check/project.yml
@@ -0,0 +1,64 @@
+name: SizeCheck
+options:
+  bundleIdPrefix: io.livekit.sizecheck
+  deploymentTarget:
+    iOS: "26.0"
+  createIntermediateGroups: true
+
+# Local SDK under test = the repo root (this PR's checkout), two levels up.
+packages:
+  LiveKit:
+    path: ../..
+
+settings:
+  base:
+    CODE_SIGNING_ALLOWED: "NO"
+    CODE_SIGNING_REQUIRED: "NO"
+    CODE_SIGN_IDENTITY: ""
+    ENABLE_BITCODE: "NO"
+    SWIFT_OPTIMIZATION_LEVEL: "-O"
+    DEAD_CODE_STRIPPING: "YES"
+
+targets:
+  EmptyApp:
+    type: application
+    platform: iOS
+    sources: [EmptyApp]
+    # xcodegen generates this Info.plist during `generate` (gitignored, not committed).
+    info:
+      path: EmptyApp/Info.plist
+      properties:
+        UILaunchScreen: {}
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: io.livekit.sizecheck.empty
+
+  LiveKitApp:
+    type: application
+    platform: iOS
+    sources: [LiveKitApp]
+    dependencies:
+      - package: LiveKit
+        product: LiveKit
+    info:
+      path: LiveKitApp/Info.plist
+      properties:
+        UILaunchScreen: {}
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: io.livekit.sizecheck.livekit
+        # Per-target link map (unique path) for per-library executable attribution.
+        LD_GENERATE_MAP_FILE: "YES"
+        LD_MAP_FILE_PATH: "$(TARGET_TEMP_DIR)/LiveKitApp-LinkMap.txt"
+
+schemes:
+  EmptyApp:
+    build:
+      targets: { EmptyApp: all }
+    archive:
+      config: Release
+  LiveKitApp:
+    build:
+      targets: { LiveKitApp: all }
+    archive:
+      config: Release
diff --git a/.github/size-check/size-check.swift b/.github/size-check/size-check.swift
new file mode 100644
index 000000000..62a1f9f51
--- /dev/null
+++ b/.github/size-check/size-check.swift
@@ -0,0 +1,309 @@
+#!/usr/bin/env swift-sh
+
+/*
+ * Copyright 2026 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import ArgumentParser // apple/swift-argument-parser ~> 1.3
+import Files // JohnSundell/Files ~> 4.2
+import Foundation
+import ShellOut // JohnSundell/ShellOut ~> 2.3
+
+// Run via: swiftly run +xcode swift-sh .github/size-check/size-check.swift [--baseline N]
+//
+// Builds an empty iOS app and a LiveKit "hello world" app (via xcodegen),
+// archives both unsigned for the arm64 device slice, and reports the SDK's
+// size impact (uncompressed `.app` delta = benchmark, compressed IPA = info)
+// plus a frameworks-vs-compiled-Swift breakdown. A non-zero `--baseline`
+// enforces a budget: the delta must stay within `baseline * (1 + tolerance%)`.
+
+struct SizeCheck: ParsableCommand {
+    static let configuration = CommandConfiguration(abstract: "Measure the LiveKit SDK's iOS app-size impact.")
+
+    @Option(help: "Directory containing project.yml and the test apps.")
+    var root = ".github/size-check"
+
+    @Option(help: "Budget for the .app delta, in MB. 0 disables the gate.")
+    var baseline = 0.0
+
+    @Option(help: "Allowed growth over the baseline, in percent.")
+    var tolerance = 5.0
+
+    /// Outcome relative to the baseline: at/under it, within tolerance, or over.
+    enum BudgetStatus { case ok, warning, over }
+
+    func run() throws {
+        let project = "\(root)/SizeCheck.xcodeproj"
+        let build = try Folder.temporary.createSubfolder(named: "size-check-\(UUID().uuidString)")
+        defer { try? build.delete() }
+
+        try grouped("xcodegen generate") { try shellOut(to: "xcodegen", arguments: ["generate"], at: root) }
+        try archive("EmptyApp", project: project, build: build)
+        try archive("LiveKitApp", project: project, build: build)
+
+        let report = try buildReport(build: build)
+        emit(report.markdown)
+        FileHandle.standardError.write(Data("app_delta_bytes=\(report.appDelta)\n".utf8))
+        switch report.status {
+        case .ok:
+            break
+        case .warning:
+            print("::warning::LiveKit SDK app-size delta \(mb(report.appDelta)) is above the baseline (still within the +\(Int(tolerance))% tolerance).")
+        case .over:
+            print("::error::LiveKit SDK app-size delta \(mb(report.appDelta)) exceeds the baseline budget — see the job summary.")
+            throw ExitCode.failure
+        }
+    }
+
+    // MARK: - Build steps
+
+    private func archive(_ scheme: String, project: String, build: Folder) throws {
+        try grouped("archive \(scheme)") {
+            do {
+                try shellOut(to: "xcodebuild", arguments: [
+                    "archive",
+                    "-project", project,
+                    "-scheme", scheme,
+                    "-configuration", "Release",
+                    "-destination", "generic/platform=iOS",
+                    "-archivePath", "\(build.path)\(scheme).xcarchive",
+                    "-derivedDataPath", "\(build.path)dd",
+                    "CODE_SIGNING_ALLOWED=NO", "CODE_SIGNING_REQUIRED=NO", "CODE_SIGN_IDENTITY=",
+                ])
+            } catch let error as ShellOutError {
+                print(error.output)
+                throw ValidationError("xcodebuild archive \(scheme) failed")
+            }
+        }
+    }
+
+    private func appPath(_ scheme: String, build: Folder) -> String {
+        "\(build.path)\(scheme).xcarchive/Products/Applications/\(scheme).app"
+    }
+
+    /// IPA = zip of `Payload/<App>.app` (no signing/thinning needed for a size proxy).
+    private func makeIPA(_ scheme: String, build: Folder) throws -> String {
+        let payload = try build.createSubfolderIfNeeded(withName: "Payload")
+        try payload.empty()
+        try Folder(path: appPath(scheme, build: build)).copy(to: payload)
+        let ipa = "\(build.path)\(scheme).ipa"
+        try? FileManager.default.removeItem(atPath: ipa)
+        try shellOut(to: "zip", arguments: ["-qr", "-X", ipa, "Payload"], at: build.path)
+        return ipa
+    }
+
+    // MARK: - Report
+
+    private struct Report {
+        let markdown: String
+        let appDelta: Int
+        let status: BudgetStatus
+    }
+
+    private struct Metrics {
+        let emptyApp, livekitApp, emptyIPA, livekitIPA: Int
+        let appDelta, ipaDelta, exec: Int
+        let frameworks: [(name: String, bytes: Int)]
+        let attribution: [(label: String, bytes: Int)]
+        let baselineBytes, limit: Int
+        let status: BudgetStatus
+    }
+
+    private func buildReport(build: Folder) throws -> Report {
+        let emptyApp = appPath("EmptyApp", build: build)
+        let livekitApp = appPath("LiveKitApp", build: build)
+        let emptyIPA = try makeIPA("EmptyApp", build: build)
+        let livekitIPA = try makeIPA("LiveKitApp", build: build)
+
+        let appDelta = bundleBytes(livekitApp) - bundleBytes(emptyApp)
+        let baselineBytes = Int(baseline * 1_048_576)
+        let limit = Int(Double(baselineBytes) * (1 + tolerance / 100))
+        let metrics = Metrics(
+            emptyApp: bundleBytes(emptyApp),
+            livekitApp: bundleBytes(livekitApp),
+            emptyIPA: fileBytes(emptyIPA),
+            livekitIPA: fileBytes(livekitIPA),
+            appDelta: appDelta,
+            ipaDelta: fileBytes(livekitIPA) - fileBytes(emptyIPA),
+            exec: fileBytes("\(livekitApp)/LiveKitApp") - fileBytes("\(emptyApp)/EmptyApp"),
+            frameworks: frameworkBinaries(in: livekitApp),
+            attribution: linkMapAttribution(buildPath: build.path),
+            baselineBytes: baselineBytes,
+            limit: limit,
+            status: budgetStatus(appDelta: appDelta, baselineBytes: baselineBytes, limit: limit),
+        )
+        return Report(markdown: render(metrics), appDelta: appDelta, status: metrics.status)
+    }
+
+    private func budgetStatus(appDelta: Int, baselineBytes: Int, limit: Int) -> BudgetStatus {
+        guard baselineBytes > 0 else { return .ok }
+        if appDelta > limit { return .over }
+        if appDelta > baselineBytes { return .warning }
+        return .ok
+    }
+
+    private func render(_ m: Metrics) -> String {
+        var md = ""
+        func line(_ string: String = "") { md += string + "\n" }
+
+        line("## 📦 LiveKit SDK — iOS app size impact")
+        line()
+        line("**Adds `\(mb(m.appDelta))` uncompressed / `\(mb(m.ipaDelta))` compressed** to an iOS app "
+            + "(arm64 device slice, Release, unsigned).")
+        line()
+        line("| Metric | Empty | LiveKit | Delta (SDK cost) |")
+        line("|---|--:|--:|--:|")
+        line("| `.app` (uncompressed — benchmark) | \(mb(m.emptyApp)) | \(mb(m.livekitApp)) | **+\(mb(m.appDelta))** |")
+        line("| IPA (zip — download, info) | \(mb(m.emptyIPA)) | \(mb(m.livekitIPA)) | +\(mb(m.ipaDelta)) |")
+        line()
+        line("### Where it goes")
+        line()
+        line("| Contributor | Size | Kind |")
+        line("|---|--:|---|")
+        line("| **Binary frameworks** | **\(mb(m.frameworks.reduce(0) { $0 + $1.bytes }))** | dynamic `.framework` |")
+        for framework in m.frameworks {
+            line("| &nbsp;&nbsp;\(framework.name) | \(mb(framework.bytes)) | prebuilt |")
+        }
+        line("| **Compiled Swift/ObjC** (in executable) | **\(mb(m.exec))** | statically linked |")
+        for entry in m.attribution where entry.bytes >= 4096 {
+            line("| &nbsp;&nbsp;\(entry.label) | \(mb(entry.bytes)) | |")
+        }
+        line()
+        if m.baselineBytes > 0 {
+            let verdict = switch m.status {
+            case .ok: "✅ within baseline"
+            case .warning: "⚠️ above baseline, within +\(Int(tolerance))% tolerance"
+            case .over: "❌ over budget"
+            }
+            line("**Budget:** baseline \(mb(m.baselineBytes)) · +\(Int(tolerance))% → \(mb(m.limit)) · "
+                + "measured **\(mb(m.appDelta))** — \(verdict)")
+            line()
+        }
+        line("<sub>Benchmark = uncompressed `.app` delta. Frameworks are included whole "
+            + "(not dead-stripped); compiled Swift scales with usage. Generated by `.github/size-check`.</sub>")
+        return md
+    }
+
+    // MARK: - Measurement helpers
+
+    private func fileBytes(_ path: String) -> Int {
+        ((try? FileManager.default.attributesOfItem(atPath: path))?[.size] as? Int) ?? 0
+    }
+
+    private func bundleBytes(_ path: String) -> Int {
+        guard let folder = try? Folder(path: path) else { return 0 }
+        return folder.files.recursive.reduce(0) { $0 + fileBytes($1.path) }
+    }
+
+    private func frameworkBinaries(in app: String) -> [(name: String, bytes: Int)] {
+        guard let frameworks = try? Folder(path: app).subfolder(named: "Frameworks") else { return [] }
+        return frameworks.subfolders
+            .filter { $0.name.hasSuffix(".framework") }
+            .compactMap { sub -> (String, Int)? in
+                let name = String(sub.name.dropLast(".framework".count))
+                guard let binary = try? sub.file(named: name) else { return nil }
+                return (name, fileBytes(binary.path))
+            }
+            .sorted { $0.1 > $1.1 }
+    }
+
+    private func library(forObjectPath path: String) -> String {
+        let buckets: [(suffix: String, label: String)] = [
+            ("/App.o", "App (hello-world)"),
+            ("/LiveKit.o", "LiveKit (SDK Swift)"),
+            ("/SwiftProtobuf.o", "SwiftProtobuf"),
+            ("/LiveKitUniFFI.o", "LiveKitUniFFI bindings"),
+            ("/LKObjCHelpers.o", "LKObjCHelpers"),
+        ]
+        for bucket in buckets where path.hasSuffix(bucket.suffix) {
+            return bucket.label
+        }
+        if path == "linker synthesized" { return "Swift metadata (linker)" }
+        return "other (runtime/shims)"
+    }
+
+    /// Sum live-symbol bytes per object file from the `ld -map`, bucketed by library.
+    private func linkMapAttribution(buildPath: String) -> [(label: String, bytes: Int)] {
+        guard let dd = try? Folder(path: "\(buildPath)dd"),
+              let map = dd.files.recursive.first(where: { $0.name == "LiveKitApp-LinkMap.txt" }),
+              let content = try? map.readAsString()
+        else { return [] }
+
+        var files: [Int: String] = [:]
+        var sizes: [Int: Int] = [:]
+        var section = ""
+        for line in content.components(separatedBy: .newlines) {
+            if let header = mapSection(of: line) {
+                section = header
+            } else if section == "objects" {
+                parseObjectLine(line, into: &files)
+            } else if section == "symbols" {
+                parseSymbolLine(line, into: &sizes)
+            }
+        }
+        var aggregate: [String: Int] = [:]
+        for (idx, size) in sizes {
+            aggregate[library(forObjectPath: files[idx] ?? "?"), default: 0] += size
+        }
+        return aggregate.filter { $0.value > 0 }.sorted { $0.value > $1.value }.map { (label: $0.key, bytes: $0.value) }
+    }
+
+    /// The section a `# ...` header line begins, or nil for a non-header line.
+    private func mapSection(of line: String) -> String? {
+        if line.hasPrefix("# Object files:") { return "objects" }
+        if line.hasPrefix("# Symbols:") { return "symbols" }
+        if line.hasPrefix("# Sections:") || line.hasPrefix("# Dead Stripped") { return "" }
+        return nil
+    }
+
+    /// `[  N] /path/to/File.o`
+    private func parseObjectLine(_ line: String, into files: inout [Int: String]) {
+        guard line.hasPrefix("["), let close = line.firstIndex(of: "]"),
+              let idx = Int(line[line.index(after: line.startIndex) ..< close].trimmingCharacters(in: .whitespaces))
+        else { return }
+        files[idx] = line[line.index(after: close)...].trimmingCharacters(in: .whitespaces)
+    }
+
+    /// `0xADDR 0xSIZE [  N] name`
+    private func parseSymbolLine(_ line: String, into sizes: inout [Int: Int]) {
+        guard let open = line.firstIndex(of: "["), let close = line.firstIndex(of: "]"), open < close,
+              let idx = Int(line[line.index(after: open) ..< close].trimmingCharacters(in: .whitespaces))
+        else { return }
+        let fields = line[..<open].split(separator: " ", omittingEmptySubsequences: true)
+        guard fields.count >= 2 else { return }
+        let hex = fields[1].hasPrefix("0x") ? String(fields[1].dropFirst(2)) : String(fields[1])
+        guard let size = Int(hex, radix: 16) else { return }
+        sizes[idx, default: 0] += size
+    }
+
+    private func mb(_ bytes: Int) -> String { String(format: "%.2f MB", Double(bytes) / 1_048_576) }
+
+    // MARK: - Output
+
+    private func grouped(_ title: String, _ body: () throws -> Void) throws {
+        print("::group::\(title)")
+        defer { print("::endgroup::") }
+        try body()
+    }
+
+    private func emit(_ markdown: String) {
+        print(markdown, terminator: "")
+        if let summary = ProcessInfo.processInfo.environment["GITHUB_STEP_SUMMARY"] {
+            try? File(path: summary).append(markdown)
+        }
+    }
+}
+
+SizeCheck.main()
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 3d7c655ed..06701265a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -198,6 +198,37 @@ jobs:
           name: docs
           path: docs.zip
           retention-days: 1
+  app-size:
+    name: App Size
+    runs-on: macos-26
+    timeout-minutes: 30
+    env:
+      # Budget for the SDK's uncompressed .app delta, in MB. Bump deliberately
+      # when a size increase is intended (see the job summary for the measured value).
+      SIZE_BASELINE_MB: "17.5"
+      SIZE_TOLERANCE_PCT: "5"
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: latest-stable
+
+      - name: Install tools
+        run: |
+          brew install xcodegen swiftly swift-sh
+          swiftly init --quiet-shell-followup --skip-install -y
+
+      # Archives an empty app + a LiveKit app (unsigned, arm64 device slice) and
+      # writes the size breakdown to the job summary, failing if over budget.
+      - name: Measure app size
+        run: |
+          swiftly run +xcode swift-sh .github/size-check/size-check.swift \
+            --baseline "$SIZE_BASELINE_MB" \
+            --tolerance "$SIZE_TOLERANCE_PCT"
+
   check-protocol:
     name: Check Protocol
     runs-on: macos-26
@@ -228,6 +259,7 @@ jobs:
           else
             echo "Working tree is clean - all Swift protobuf files are up to date"
           fi
+
   check-changes:
     name: Check Changes
     if: github.event_name == 'pull_request'