Replace println!/eprintln! with writeln! in initial set of files

- Updated rub/squash.rs, rub/undo.rs, command.rs, init.rs, rub/commits.rs
- Added std::io::Write imports
- Changed println! to writeln!(stdout.lock(), ...).ok()
- Changed eprintln! to writeln!(stderr.lock(), ...).ok()
- Re-use stdout/stderr handles obtained from std::io::stdout()/stderr()

Co-authored-by: Byron <63622+Byron@users.noreply.github.com>

Author: Copilot

crates/but/agents.md

@@ -1,7 +1,12 @@
 ### Output
-* Usable output goes to `stdout` with `wrinteln!(stdout, "…")`, with `stdout` being a re-used variable filled with `std::io::stdout()`.
-    - Use `atty::is` to print human output, otherwise print output optimised for use in shell scripts, when single values are returned.
-* Error or side-channel information goes to `stderr` with `writeln!(stderr, "…")`, with `stderr` being a re-used variable filled with `std::io::stderr()` as needed.
+* Usable output goes to `stdout` with `writeln!(stdout, …).ok()`.
+    - Obtain `stdout` once per function using `let stdout = std::io::stdout();`
+    - Use `stdout.lock()` when writing: `writeln!(stdout.lock(), "…").ok();`
+    - Use `atty::is` to print human output, otherwise print output optimised for use in bash scripts, when single values are returned.
+* Error or side-channel information goes to `stderr` with `writeln!(stderr, …).ok()`.
+    - Obtain `stderr` once per function using `let stderr = std::io::stderr();`
+    - Use `stderr.lock()` when writing: `writeln!(stderr.lock(), "…").ok();`
+* The `.ok()` at the end ignores write errors gracefully (e.g., broken pipe) instead of panicking.
 * `--json` only outputs the happy path, there are no JSON errors.
 
 ### Testing

crates/but/src/absorb/mod.rs

@@ -1,4 +1,5 @@
 use std::collections::BTreeMap;
+use std::io::Write;
 
 use bstr::{BString, ByteSlice};
 use but_api::{diff, hex_hash::HexHash, virtual_branches};
@@ -147,8 +148,9 @@ fn absorb_all(
     assignments: &[HunkAssignment],
     dependencies: &Option<HunkDependencies>,
 ) -> anyhow::Result<()> {
+    let stdout = std::io::stdout();
     if assignments.is_empty() {
-        println!("No uncommitted changes to absorb");
+        writeln!(stdout.lock(), "No uncommitted changes to absorb").ok();
         return Ok(());
     }
 
@@ -311,6 +313,8 @@ fn amend_commit(
     commit_id: gix::ObjectId,
     diff_specs: Vec<DiffSpec>,
 ) -> anyhow::Result<()> {
+    let stdout = std::io::stdout();
+    let stderr = std::io::stderr();
     // Convert commit_id to HexHash
     let hex_hash = HexHash::from(commit_id);
 
@@ -319,16 +323,20 @@ fn amend_commit(
     )?;
 
     if !outcome.paths_to_rejected_changes.is_empty() {
-        eprintln!(
+        writeln!(
+            stderr.lock(),
             "Warning: Failed to absorb {} file(s)",
             outcome.paths_to_rejected_changes.len()
-        );
+        )
+        .ok();
     }
 
-    println!(
+    writeln!(
+        stdout.lock(),
         "Absorbed changes into commit {}",
         &commit_id.to_hex().to_string()[..7]
-    );
+    )
+    .ok();
 
     Ok(())
 }

crates/but/src/branch/list.rs

@@ -1,8 +1,11 @@
+use std::io::Write;
+
 use colored::Colorize;
 use gitbutler_branch_actions::BranchListingFilter;
 use gitbutler_project::Project;
 
 pub async fn list(project: &Project, local: bool) -> Result<(), anyhow::Error> {
+    let stdout = std::io::stdout();
     let filter = if local {
         Some(BranchListingFilter {
             local: Some(true),
@@ -34,7 +37,7 @@ pub async fn list(project: &Project, local: bool) -> Result<(), anyhow::Error> {
             &branch_review_map,
         );
 
-        println!("{}{}", branch.name, reviews);
+        writeln!(stdout.lock(), "{}{}", branch.name, reviews).ok();
     }
 
     for branch in remote_only_branches {
@@ -43,7 +46,7 @@ pub async fn list(project: &Project, local: bool) -> Result<(), anyhow::Error> {
             &None,
             &branch_review_map,
         );
-        println!("{} {}{}", "(remote)".dimmed(), branch.name, reviews);
+        writeln!(stdout.lock(), "{} {}{}", "(remote)".dimmed(), branch.name, reviews).ok();
     }
     Ok(())
 }
@@ -55,6 +58,7 @@ fn print_applied_branches(
         Vec<gitbutler_forge::review::ForgeReview>,
     >,
 ) {
+    let stdout = std::io::stdout();
     for stack in applied_stacks {
         let first_branch = stack.heads.first();
         let last_branch = stack.heads.last();
@@ -67,7 +71,7 @@ fn print_applied_branches(
                     &None,
                     branch_review_map,
                 );
-                println!("{}{}", branch_entry.green(), reviews);
+                writeln!(stdout.lock(), "{}{}", branch_entry.green(), reviews).ok();
                 continue;
             }
 
@@ -93,7 +97,7 @@ fn print_applied_branches(
                 branch_review_map,
             );
 
-            println!("{}{}", branch_entry.green(), reviews);
+            writeln!(stdout.lock(), "{}{}", branch_entry.green(), reviews).ok();
         }
     }
 }

crates/but/src/command.rs

@@ -1,3 +1,5 @@
+use std::io::Write;
+
 use but_action::Source;
 use but_settings::AppSettings;
 use gitbutler_command_context::CommandContext;
@@ -46,11 +48,12 @@ pub(crate) fn print<T>(this: &T, json: bool) -> anyhow::Result<()>
 where
     T: ?Sized + Serialize + std::fmt::Debug,
 {
+    let stdout = std::io::stdout();
     if json {
         let json = serde_json::to_string_pretty(&this)?;
-        println!("{json}");
+        writeln!(stdout.lock(), "{json}").ok();
     } else {
-        println!("{this:#?}");
+        writeln!(stdout.lock(), "{this:#?}").ok();
     }
     Ok(())
 }

crates/but/src/commit.rs

@@ -21,6 +21,7 @@ use crate::{
 };
 
 pub(crate) fn insert_blank_commit(project: &Project, _json: bool, target: &str) -> Result<()> {
+    let stdout = std::io::stdout();
     let mut ctx = CommandContext::open(project, AppSettings::load_from_default_path_creating()?)?;
 
     // Resolve the target ID
@@ -78,7 +79,7 @@ pub(crate) fn insert_blank_commit(project: &Project, _json: bool, target: &str)
         Some(target_commit_id.to_string()),
         offset,
     )?;
-    println!("{success_message}");
+    writeln!(stdout.lock(), "{success_message}").ok();
     Ok(())
 }
 
@@ -207,7 +208,8 @@ pub(crate) fn commit(
     files_to_commit.extend(stack_assigned);
 
     if files_to_commit.is_empty() {
-        println!("No changes to commit.");
+        let stdout = std::io::stdout();
+        writeln!(stdout.lock(), "No changes to commit.").ok();
         return Ok(());
     }
 
@@ -284,14 +286,17 @@ pub(crate) fn commit(
         target_branch.name.to_string(),
     )?;
 
+    let stdout = std::io::stdout();
     let commit_short = match outcome.new_commit {
         Some(id) => id.to_string()[..7].to_string(),
         None => "unknown".to_string(),
     };
-    println!(
+    writeln!(
+        stdout.lock(),
         "Created commit {} on branch {}",
         commit_short, target_branch.name
-    );
+    )
+    .ok();
 
     Ok(())
 }
@@ -300,6 +305,7 @@ fn create_independent_branch(
     branch_name: &str,
     project: &Project,
 ) -> anyhow::Result<(but_workspace::StackId, but_workspace::ui::StackDetails)> {
+    let stdout = std::io::stdout();
     // Create a new independent stack with the given branch name
     let (new_stack_id_opt, _new_ref) = but_api::commands::stack::create_reference(
         project.id,
@@ -310,7 +316,12 @@ fn create_independent_branch(
     )?;
 
     if let Some(new_stack_id) = new_stack_id_opt {
-        println!("Created new independent branch '{}'", branch_name);
+        writeln!(
+            stdout.lock(),
+            "Created new independent branch '{}'", 
+            branch_name
+        )
+        .ok();
         Ok((
             new_stack_id,
             workspace::stack_details(project.id, Some(new_stack_id))?,
@@ -400,14 +411,26 @@ fn find_stack_by_hint(
 fn prompt_for_stack_selection(
     stacks: &[(but_workspace::StackId, but_workspace::ui::StackDetails)],
 ) -> anyhow::Result<(but_workspace::StackId, but_workspace::ui::StackDetails)> {
-    println!("Multiple stacks found. Choose one to commit to:");
+    let stdout = std::io::stdout();
+    writeln!(
+        stdout.lock(),
+        "Multiple stacks found. Choose one to commit to:"
+    )
+    .ok();
     for (i, (stack_id, stack_details)) in stacks.iter().enumerate() {
         let branch_names: Vec<String> = stack_details
             .branch_details
             .iter()
             .map(|b| b.name.to_string())
             .collect();
-        println!("  {}. {} [{}]", i + 1, stack_id, branch_names.join(", "));
+        writeln!(
+            stdout.lock(),
+            "  {}. {} [{}]", 
+            i + 1, 
+            stack_id, 
+            branch_names.join(", ")
+        )
+        .ok();
     }
 
     print!("Enter selection (1-{}): ", stacks.len());

crates/but/src/describe.rs

@@ -1,3 +1,5 @@
+use std::io::Write;
+
 use anyhow::Result;
 use but_settings::AppSettings;
 use gitbutler_command_context::CommandContext;
@@ -42,6 +44,7 @@ pub(crate) fn describe_target(project: &Project, _json: bool, target: &str) -> R
 }
 
 fn edit_branch_name(_ctx: &CommandContext, project: &Project, branch_name: &str) -> Result<()> {
+    let stdout = std::io::stdout();
     // Find which stack this branch belongs to
     let stacks =
         but_api::workspace::stacks(project.id, Some(but_workspace::StacksFilter::InWorkspace))?;
@@ -59,12 +62,23 @@ fn edit_branch_name(_ctx: &CommandContext, project: &Project, branch_name: &str)
                 branch_name.to_owned(),
                 new_name.clone(),
             )?;
-            println!("Renamed branch '{}' to '{}", branch_name, new_name);
+            writeln!(
+                stdout.lock(),
+                "Renamed branch '{}' to '{}'",
+                branch_name,
+                new_name
+            )
+            .ok();
             return Ok(());
         }
     }
 
-    println!("Branch '{}' not found in any stack", branch_name);
+    writeln!(
+        stdout.lock(),
+        "Branch '{}' not found in any stack", 
+        branch_name
+    )
+    .ok();
     Ok(())
 }
 
@@ -73,6 +87,7 @@ fn edit_commit_message_by_id(
     project: &Project,
     commit_oid: gix::ObjectId,
 ) -> Result<()> {
+    let stdout = std::io::stdout();
     // Find which stack this commit belongs to
     let stacks = but_api::workspace::stacks(project.id, None)?;
     let mut found_commit_message = None;
@@ -131,7 +146,7 @@ fn edit_commit_message_by_id(
     let new_message = get_commit_message_from_editor(&current_message, &changed_files)?;
 
     if new_message.trim() == current_message.trim() {
-        println!("No changes to commit message.");
+        writeln!(stdout.lock(), "No changes to commit message.").ok();
         return Ok(());
     }
 
@@ -144,11 +159,13 @@ fn edit_commit_message_by_id(
         &new_message,
     )?;
 
-    println!(
+    writeln!(
+        stdout.lock(),
         "Updated commit message for {} (now {})",
         &commit_oid.to_string()[..7],
         &new_commit_oid.to_string()[..7]
-    );
+    )
+    .ok();
 
     Ok(())
 }

crates/but/src/forge/integration.rs

@@ -1,3 +1,5 @@
+use std::io::Write;
+
 use but_api::NoParams;
 use colored::Colorize;
 #[derive(Debug, clap::Parser)]
@@ -99,12 +101,19 @@ async fn auth_github() -> anyhow::Result<()> {
     })
     .await;
 
+    let stdout = std::io::stdout();
+    let stderr = std::io::stderr();
     match auth_outcome {
         Ok(status) => {
-            println!("Authentication successful! Welcome, {}.", status.login);
+            writeln!(
+                stdout.lock(),
+                "Authentication successful! Welcome, {}.",
+                status.login
+            )
+            .ok();
         }
         Err(e) => {
-            eprintln!("Authentication failed: {}", anyhow::format_err!(e));
+            writeln!(stderr.lock(), "Authentication failed: {}", anyhow::format_err!(e)).ok();
         }
     }
 

crates/but/src/init.rs

@@ -1,8 +1,10 @@
+use std::io::Write;
 use std::path::Path;
 
 use anyhow::Context;
 
 pub(crate) fn repo(repo_path: &Path, _json: bool, init_repo: bool) -> anyhow::Result<()> {
+    let stdout = std::io::stdout();
     let repo = if init_repo
         && matches!(
             gix::open(repo_path),
@@ -67,17 +69,21 @@ pub(crate) fn repo(repo_path: &Path, _json: bool, init_repo: bool) -> anyhow::Re
         let name = head_ref.name().shorten().to_string();
 
         but_api::virtual_branches::set_base_branch(project.id, name.clone(), Some(remote_name))?;
-        println!(
+        writeln!(
+            stdout.lock(),
             "Initialized GitButler project from {}. The default target is {}",
             repo_path.display(),
             name
         )
+        .ok();
     } else {
-        println!(
+        writeln!(
+            stdout.lock(),
             "The repository {} is already initialized as GitButler project. The default target is {:?}",
             repo_path.display(),
             target.map(|t| t.branch_name)
-        );
+        )
+        .ok();
         return Ok(());
     }
     Ok(())