fix: 除外した差分に本文の文字数を配分しない

src/git/service.rs

@@ -803,9 +803,15 @@ impl GitService {
                 Some(ignore) => Self::filter_ignored_files(&raw, ignore),
                 None => raw.clone(),
             };
-            let content = Self::summarize_diff(&filtered);
+            let ignored = filtered != raw;
+            // パスと省略通知は一覧に載せるので、本文の予算を使わない。
+            let content = if ignored {
+                String::new()
+            } else {
+                Self::summarize_diff(&filtered)
+            };
             let mut overview = Self::diff_block_overview(block);
-            if filtered != raw {
+            if ignored {
                 overview.push(' ');
                 overview.push_str(IGNORED_CONTENT_NOTICE);
             } else if content != filtered {
@@ -825,12 +831,13 @@ impl GitService {
         let mut sizes = excerpts
             .iter()
             .enumerate()
+            .filter(|(_, excerpt)| !excerpt.content.is_empty())
             .map(|(index, excerpt)| (excerpt.content.chars().count(), index))
             .collect::<Vec<_>>();
         sizes.sort_unstable();
         let mut allocations = vec![0; excerpts.len()];
         // 本文を連結する改行も本文予算に含める。一覧と通知はこの予算の別枠。
-        let mut remaining = MAX_DIFF_CHARS.saturating_sub(excerpts.len().saturating_sub(1));
+        let mut remaining = MAX_DIFF_CHARS.saturating_sub(sizes.len().saturating_sub(1));
         for (position, (size, index)) in sizes.iter().enumerate() {
             let share = remaining / (sizes.len() - position);
             allocations[*index] = (*size).min(share);
@@ -2588,6 +2595,38 @@ index 1234567..abcdefg 100644
         assert!(!result.contains('\u{fffd}'));
     }
 
+    #[rstest::rstest]
+    #[case(false)]
+    #[case(true)]
+    fn test_ignored_excerpts_do_not_spend_body_or_separator_budget(#[case] only_ignored: bool) {
+        let dir = tempfile::tempdir().unwrap();
+        let mut builder = GitignoreBuilder::new(dir.path());
+        builder.add_line(None, "data/").unwrap();
+        let ignore = builder.build().unwrap();
+        // 除外ファイルの区切りだけで予算を使い切る件数も扱う。
+        let count = MAX_DIFF_CHARS + 2;
+        let mut diff = (0..count)
+            .map(|index| {
+                format!(
+                    "diff --git a/data/{index}.txt b/data/{index}.txt\n@@ -0,0 +1 @@\n+hidden\n"
+                )
+            })
+            .collect::<String>();
+        let visible = "diff --git a/visible.txt b/visible.txt\n@@ -0,0 +1 @@\n+visible change";
+        if !only_ignored {
+            diff.push_str(visible);
+        }
+        let filtered = GitService::filter_ignored_files(&diff, &ignore);
+        let result = GitService::truncate_diff_with_source(&filtered, &diff, Some(&ignore));
+        let (overview, body) = result
+            .split_once("body budget 10000 characters]\n\n")
+            .unwrap();
+        assert_eq!(overview.matches(IGNORED_CONTENT_NOTICE).count(), count);
+        assert!(!overview.contains("[body truncated]"));
+        assert!(!body.contains("hidden"));
+        assert_eq!(body, if only_ignored { "" } else { visible });
+    }
+
     #[test]
     fn test_truncate_diff_exactly_at_limit() {
         // 10000文字ちょうどの場合は切り詰めない

tests/cli_integration.rs

@@ -15,6 +15,81 @@ macro_rules! git_sc {
     };
 }
 
+/// 除外対象の数にかかわらず、残った本文だけで予算を分ける。
+#[rstest::rstest]
+#[case(false)]
+#[case(true)]
+#[cfg(unix)]
+fn test_many_ignored_files_do_not_consume_prompt_body_budget(#[case] large_bodies: bool) {
+    let dir = setup_git_repo_with_commit();
+    let path = setup_fake_opencode_path(&dir);
+    std::fs::write(dir.path().join(".git-sc"), "providers = [\"opencode\"]\n").unwrap();
+    std::fs::write(dir.path().join(".git-sc-ignore"), "data/\n").unwrap();
+    std::fs::create_dir(dir.path().join("data")).unwrap();
+    for index in 0..254 {
+        std::fs::write(
+            dir.path()
+                .join(format!("data/record-{index:03}-{}.txt", "x".repeat(60))),
+            "hidden-data-value\n",
+        )
+        .unwrap();
+    }
+    let count = if large_bodies { 1500 } else { 40 };
+    for name in ["first", "second"] {
+        std::fs::write(
+            dir.path().join(format!("{name}.txt")),
+            format!("{name} visible body line\n").repeat(count),
+        )
+        .unwrap();
+    }
+    let staged = std::process::Command::new("git")
+        .args(["add", "data", "first.txt", "second.txt"])
+        .current_dir(dir.path())
+        .output()
+        .unwrap();
+    assert!(staged.status.success());
+    let output = git_sc!()
+        .args(["--dry-run", "--debug", "-p", "opencode"])
+        .env("PATH", &path)
+        .env("HOME", dir.path())
+        .env("XDG_CONFIG_HOME", dir.path())
+        .current_dir(dir.path())
+        .assert()
+        .success()
+        .get_output()
+        .stdout
+        .clone();
+    let output = String::from_utf8(output).unwrap();
+    let changes = output.split_once("<changes>\n").unwrap().1;
+    let changes = changes.split_once("\n</changes>").unwrap().0;
+    let (_, body) = changes
+        .split_once("body budget 10000 characters]\n\n")
+        .unwrap();
+    assert_eq!(changes.matches("[File] ").count(), 256);
+    assert_eq!(
+        changes
+            .matches("[content omitted by .git-sc-ignore]")
+            .count(),
+        254
+    );
+    assert!(!changes.contains("hidden-data-value"));
+    assert!(!body.contains("data/record-"));
+    assert!(body.chars().count() <= 10000);
+    for name in ["first", "second"] {
+        let line = format!("+{name} visible body line");
+        let actual = body.lines().filter(|candidate| *candidate == line).count();
+        if large_bodies {
+            assert!(actual > 0 && actual < count, "{name}: {actual}");
+        } else {
+            assert_eq!(actual, count, "{name}");
+        }
+    }
+    assert_eq!(
+        changes.matches("[body truncated]").count(),
+        if large_bodies { 2 } else { 0 }
+    );
+}
+
 /// 大きな先頭ファイルが後続ファイルを隠さず、実際に送るプロンプトに全体像を残す。
 #[test]
 #[cfg(unix)]