feat: initial implementation of AI Commit Ext VS Code extension

- Add VS Code extension with OpenCode AI integration
- Generate Conventional Commit messages via SCM header button
- Include gitService for staged changes detection
- Include opencodeService for CLI invocation
- Add configuration options for model, includeUnstaged, notifications
- Add button disable during generation with progress indicator
- Add sparkle icon for the action button
- Include package.json, tsconfig, and basic project setup

src/opencodeService.ts

@@ -0,0 +1,128 @@
+import { exec, spawn, ExecException } from "child_process";
+import * as vscode from "vscode";
+import { getGitDiff, getRepositoryRoot } from "./gitService";
+
+export interface GenerateOptions {
+    model?: string;
+}
+
+const DEFAULT_PROMPT = `You are a helpful assistant that generates git commit messages.
+Generate a concise Conventional Commit message (max 72 characters for the subject line).
+Format: <type>(<scope>): <description>
+
+Types: feat, fix, refactor, docs, style, test, chore, perf, ci, build, revert
+
+Only output the commit message, nothing else.`;
+
+export async function isOpenCodeAvailable(): Promise<boolean> {
+    return new Promise((resolve) => {
+        exec("which opencode", (error: ExecException | null) => {
+            resolve(!error);
+        });
+    });
+}
+
+export async function generateCommitMessage(
+    options: GenerateOptions = {},
+): Promise<string> {
+    const opencodeAvailable = await isOpenCodeAvailable();
+    if (!opencodeAvailable) {
+        throw new Error(
+            "OpenCode is not installed. Please install it from https://opencode.ai",
+        );
+    }
+
+    const diff = await getGitDiff();
+    const repoRoot = await getRepositoryRoot();
+
+    const config = vscode.workspace.getConfiguration("aiCommitExt");
+    const model = options.model || config.get<string>("model", "");
+
+    const prompt = `${DEFAULT_PROMPT}
+
+Here are the git changes:
+${diff}
+
+Generate a concise Conventional Commit message for these changes:`;
+
+    return new Promise((resolve, reject) => {
+        const args: string[] = ["run", "--format", "default"];
+
+        if (model) {
+            args.push("--model", model);
+        }
+
+        const proc = spawn("opencode", args, {
+            stdio: ["pipe", "pipe", "pipe"],
+            shell: false,
+            cwd: repoRoot || undefined,
+        });
+
+        let stdout = "";
+        let stderr = "";
+
+        proc.stdout.on("data", (data: Buffer) => {
+            stdout += data.toString();
+        });
+        proc.stderr.on("data", (data: Buffer) => {
+            stderr += data.toString();
+        });
+        proc.stdin?.write(prompt + "\n", (err) => {
+            if (err) {
+                new Error(`OpenCode write error with ${err}`);
+            }
+            proc.stdin?.end();
+        });
+
+        proc.on("close", (code: number | null) => {
+            if (code !== 0) {
+                reject(
+                    new Error(`OpenCode exited with code ${code}: ${stderr}`),
+                );
+                return;
+            }
+
+            const message = parseCommitMessage(stdout);
+            resolve(message);
+        });
+
+        proc.on("error", (err: Error) => {
+            reject(new Error(`Failed to run opencode: ${err.message}`));
+        });
+
+        setTimeout(() => {
+            proc.kill();
+            reject(new Error("OpenCode timed out"));
+        }, 120000);
+    });
+}
+
+function parseCommitMessage(output: string): string {
+    const lines = output.split("\n").filter((line) => line.trim());
+
+    for (const line of lines) {
+        const trimmed = line.trim();
+
+        if (
+            trimmed.includes(":") &&
+            (trimmed.startsWith("feat") ||
+                trimmed.startsWith("fix") ||
+                trimmed.startsWith("refactor") ||
+                trimmed.startsWith("docs") ||
+                trimmed.startsWith("style") ||
+                trimmed.startsWith("test") ||
+                trimmed.startsWith("chore") ||
+                trimmed.startsWith("perf") ||
+                trimmed.startsWith("ci") ||
+                trimmed.startsWith("build") ||
+                trimmed.startsWith("revert"))
+        ) {
+            return trimmed.substring(0, 200);
+        }
+    }
+
+    const cleaned =
+        output.trim().split("\n")[0]?.substring(0, 200) ||
+        "chore: generated commit message";
+    return cleaned;
+}