Fix diff viewer: fetch PR .diff instead of relying on per-file patch; bump to 1.4

This Gitea instance never returns a 'patch' field from /pulls/{n}/files (the
field is absent for all files, regardless of size), so the diff viewer always
fell back to 'Diff too large to preview'. Now DiffView fetches the PR's .diff
endpoint (plain-text unified diff), extracts the hunks for the selected file,
and renders them colour-coded. Bump to 1.4.

GiteaPR.xcodeproj/project.pbxproj

@@ -187,7 +187,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 4;
+				CURRENT_PROJECT_VERSION = 5;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -197,7 +197,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.3;
+				MARKETING_VERSION = 1.4;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;
@@ -211,7 +211,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 4;
+				CURRENT_PROJECT_VERSION = 5;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -221,7 +221,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.3;
+				MARKETING_VERSION = 1.4;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;

GiteaPR/Detail/DiffView.swift

@@ -2,32 +2,79 @@ import SwiftUI
 
 /// Read-only unified diff viewer for a single changed file.
 ///
-/// Parses a Gitea unified diff patch into line hunks so added/deleted lines can
-/// be colour-coded. Gitea only returns `patch` for small diffs; large files
-/// fall back to a raw text view.
+/// This Gitea instance does NOT return a per-file `patch` from
+/// `/pulls/{n}/files` (the field is absent), so the diff is fetched from the
+/// PR's `.diff` endpoint and the hunks belonging to this file are extracted.
+/// Added/deleted lines are colour-coded.
 struct DiffView: View {
+    let repo: Repository
+    let prNumber: Int
     let file: ChangedFile
+    @State private var lines: [DiffLine] = []
+    @State private var isLoading = true
+    @State private var errorMessage: String?
 
     var body: some View {
         Group {
-            if let patch = file.patch, !patch.isEmpty {
+            if isLoading {
+                ProgressView("Loading diff…")
+            } else if let errorMessage {
+                ContentUnavailableView(
+                    "Couldn't load diff",
+                    systemImage: "doc.text",
+                    description: Text(errorMessage))
+            } else {
                 ScrollView([.horizontal, .vertical]) {
                     LazyVStack(alignment: .leading, spacing: 0) {
-                        ForEach(parse(patch)) { line in
+                        ForEach(lines) { line in
                             diffLine(line)
                         }
                     }
                     .font(.caption.monospaced())
                 }
-            } else {
-                ContentUnavailableView(
-                    "Diff too large to preview",
-                    systemImage: "doc.text",
-                    description: Text("Gitea didn't return a patch for this file."))
             }
         }
         .navigationTitle(file.filename)
         .navigationBarTitleDisplayMode(.inline)
+        .task { await load() }
+    }
+
+    private func load() async {
+        isLoading = true
+        errorMessage = nil
+        defer { isLoading = false }
+        guard let client = SettingsStore.shared.client() else {
+            errorMessage = "Not configured."
+            return
+        }
+        do {
+            let full = try await client.diff(owner: repo.owner.login,
+                                             repo: repo.name,
+                                             number: prNumber)
+            let patch = extractSection(named: file.filename, from: full)
+            lines = parse(patch.isEmpty ? full : patch)
+            if lines.isEmpty {
+                errorMessage = "No diff content for this file."
+            }
+        } catch {
+            errorMessage = error.localizedDescription
+        }
+    }
+
+    /// Extract the unified-diff block for `filename` from a multi-file diff.
+    /// Falls back to the whole diff if the header can't be matched.
+    private func extractSection(named filename: String, from diff: String) -> String {
+        let marker = "+++ b/\(filename)"
+        guard let idx = diff.range(of: marker)?.upperBound else {
+            return ""
+        }
+        let tail = String(diff[idx...])
+        // Find the next "diff --git " after this file's header to delimit it.
+        let rest = tail.dropFirst(marker.count)
+        if let next = rest.range(of: "\ndiff --git ") {
+            return String(tail[..<next.lowerBound])
+        }
+        return tail
     }
 
     private func diffLine(_ line: DiffLine) -> some View {

GiteaPR/Detail/Tabs.swift

@@ -106,7 +106,7 @@ struct FilesTab: View {
                 }
             }
             .navigationDestination(for: ChangedFile.self) { file in
-                DiffView(file: file)
+                DiffView(repo: vm.repo, prNumber: vm.prNumber, file: file)
             }
         }
     }

GiteaPR/Networking/GiteaClient.swift

@@ -118,6 +118,18 @@ struct GiteaClient {
         _ = try await request(path, method: "POST")
     }
 
+    /// Raw unified diff for a PR as plain text (from the `.diff` endpoint).
+    /// This Gitea instance does NOT return `patch` per file in
+    /// `/pulls/{n}/files` (the field is absent), so the diff must come from
+    /// here. The response is `text/plain`, not JSON.
+    func diff(owner: String, repo: String, number: Int) async throws -> String {
+        let data = try await request("repos/\(owner)/\(repo)/pulls/\(number).diff")
+        guard let text = String(data: data, encoding: .utf8) else {
+            throw APIError.invalidResponse
+        }
+        return text
+    }
+
     // MARK: - User
 
     /// Current authenticated user (for the "Test connection" button and