feat: Add ++difffold option to GinBuffer

Add ++difffold option to enable automatic folding for file sections in
unified diff output. Auto-enable in show action for better navigation
of multi-file diffs.

Changes:
- Add ++difffold option parsing in buffer command
- Initialize difffold when ++difffold is present
- Auto-enable ++difffold in show action
- Update documentation with ++difffold usage examples

Author: lambdalisue

denops/gin/action/show.ts

@@ -61,6 +61,7 @@ async function doShow(
       `++opener=${opener}`,
       ...(emojify ? [`++emojify`] : []),
       `++diffjump=${x.commit}`,
+      `++difffold`,
       "show",
       x.commit,
     ]);

denops/gin/command/buffer/command.ts

@@ -12,6 +12,7 @@ export type ExecOptions = {
   opener?: string;
   emojify?: boolean;
   diffjump?: string;
+  difffold?: boolean;
   filetype?: string;
   cmdarg?: string;
   mods?: string;
@@ -36,6 +37,7 @@ export async function exec(
       monochrome: unnullish(options.monochrome, (v) => v ? "" : undefined),
       emojify: unnullish(options.emojify, (v) => v ? "" : undefined),
       diffjump: options.diffjump,
+      difffold: unnullish(options.difffold, (v) => v ? "" : undefined),
       filetype: options.filetype ?? "gin-buffer",
     },
     fragment: `${args.join(" ")}$`,

denops/gin/command/buffer/edit.ts

@@ -17,6 +17,7 @@ import {
 } from "../../util/ansi_escape_code.ts";
 import { execute } from "../../git/executor.ts";
 import { init as initDiffJump } from "../../feat/diffjump/jump.ts";
+import { init as initDiffFold } from "../../feat/difffold/fold.ts";
 
 export async function edit(
   denops: Denops,
@@ -50,11 +51,16 @@ export async function edit(
     emojify: "emojify" in (params ?? {}),
   });
 
-  // Initialize diff jump functionality if ++jump option is present
+  // Initialize diff jump functionality if ++diffjump option is present
   const jumpCommitish = params?.diffjump;
   if (jumpCommitish !== undefined) {
     await initDiffJump(denops, bufnr, "buffer");
   }
+
+  // Initialize diff fold functionality if ++difffold option is present
+  if ("difffold" in (params ?? {})) {
+    await initDiffFold(denops, bufnr);
+  }
 }
 
 export type ExecOptions = {

denops/gin/command/buffer/main.ts

@@ -98,6 +98,7 @@ async function command(
     "opener",
     "emojify",
     "diffjump",
+    "difffold",
     "filetype",
     ...builtinOpts,
   ]);
@@ -108,6 +109,7 @@ async function command(
     opener: opts.opener,
     emojify: unnullish(opts.emojify, () => true),
     diffjump: opts.diffjump,
+    difffold: unnullish(opts.difffold, () => true),
     filetype: opts.filetype,
     cmdarg: formatOpts(opts, builtinOpts).join(" "),
     mods,

doc/gin.txt

@@ -151,6 +151,15 @@ COMMANDS					*gin-commands*
 		:GinBuffer ++diffjump show HEAD
 		:GinBuffer ++diffjump=abc123 show abc123
 		:GinBuffer ++diffjump log -p -1
+<
+	++difffold
+		Enable automatic folding for file sections in unified diff
+		output. Each file in the diff will be folded separately,
+		making it easier to navigate large diffs with multiple files.
+		For example:
+>
+		:GinBuffer ++difffold show HEAD
+		:GinBuffer ++diffjump ++difffold log -p -1
 <
 	++filetype={filetype}
 		Specifies the filetype to set for the buffer. Defaults to