feat: add render-md json input flow

tests/cli_parse_tests.rs

@@ -16,13 +16,7 @@ fn parse_fetch_default_format() {
 
 #[test]
 fn parse_render_md_requires_input() {
-    let cli = Cli::try_parse_from([
-        "gitea-pr-review",
-        "render-md",
-        "--in",
-        "sample.json",
-    ])
-    .unwrap();
+    let cli = Cli::try_parse_from(["gitea-pr-review", "render-md", "--in", "sample.json"]).unwrap();
 
     match cli.command {
         Commands::RenderMd(args) => {

tests/e2e_smoke_tests.rs

@@ -0,0 +1,94 @@
+use assert_cmd::Command;
+use tempfile::NamedTempFile;
+
+#[test]
+fn render_md_reads_json_and_outputs_markdown_to_stdout() {
+    let input = NamedTempFile::new().unwrap();
+    std::fs::write(
+        input.path(),
+        r#"{
+  "meta": {
+    "repo": "org/repo",
+    "pr_index": 1,
+    "title": "t",
+    "state": "open",
+    "author": "a",
+    "base_branch": "main",
+    "head_branch": "f",
+    "created_at": "2026-04-08T10:00:00Z",
+    "updated_at": "2026-04-08T11:00:00Z",
+    "merged_at": null
+  },
+  "commits": [],
+  "diff_stat": {
+    "files_changed": 0,
+    "additions": 0,
+    "deletions": 0,
+    "files": []
+  },
+  "reviews": [],
+  "threads": []
+}"#,
+    )
+    .unwrap();
+
+    let mut cmd = Command::cargo_bin("gitea-pr-review").unwrap();
+    let assert = cmd
+        .args(["render-md", "--in", input.path().to_str().unwrap()])
+        .assert()
+        .success();
+
+    let stdout = String::from_utf8(assert.get_output().stdout.clone()).unwrap();
+    assert!(stdout.contains("# org/repo `#1` t"));
+    assert!(stdout.contains("## Metadata"));
+}
+
+#[test]
+fn render_md_writes_to_out_file_when_requested() {
+    let input = NamedTempFile::new().unwrap();
+    std::fs::write(
+        input.path(),
+        r#"{
+  "meta": {
+    "repo": "org/repo",
+    "pr_index": 2,
+    "title": "t2",
+    "state": "open",
+    "author": "a",
+    "base_branch": "main",
+    "head_branch": "f",
+    "created_at": "2026-04-08T10:00:00Z",
+    "updated_at": "2026-04-08T11:00:00Z",
+    "merged_at": null
+  },
+  "commits": [],
+  "diff_stat": {
+    "files_changed": 0,
+    "additions": 0,
+    "deletions": 0,
+    "files": []
+  },
+  "reviews": [],
+  "threads": []
+}"#,
+    )
+    .unwrap();
+
+    let output = NamedTempFile::new().unwrap();
+
+    Command::cargo_bin("gitea-pr-review")
+        .unwrap()
+        .args([
+            "render-md",
+            "--in",
+            input.path().to_str().unwrap(),
+            "--out",
+            output.path().to_str().unwrap(),
+        ])
+        .assert()
+        .success();
+
+    let written = std::fs::read_to_string(output.path()).unwrap();
+    assert!(written.contains("# org/repo `#2` t2"));
+    assert!(written.contains("## Metadata"));
+}

tests/render_json_tests.rs

@@ -1,4 +1,6 @@
-use gitea_pr_review::model::{CommentItem, CommentThread, DiffStat, FileStat, PrMeta, PrReviewDocument};
+use gitea_pr_review::model::{
+    CommentItem, CommentThread, DiffStat, FileStat, PrMeta, PrReviewDocument,
+};
 
 #[test]
 fn model_json_roundtrip() {