feat(cli): add JSON output to rub, stage, amend, and squash handlers

Commands that previously only produced human-readable output (rub,
stage, amend, move, squash) now emit structured JSON when --json is
used. This makes the 'result' field in --status-after JSON responses
meaningful instead of null.

- stage/assign: {"ok": true}
- amend: {"ok": true, "newCommitId": "..."}
- squash: {"ok": true, "newCommitId": "...", "squashedCount": N}
- move: {"ok": true}

Author: krlvi

crates/but/src/command/legacy/rub/amend.rs

@@ -26,15 +26,21 @@ pub(crate) fn uncommitted_to_commit(
         .collect();
 
     let mut guard = ctx.exclusive_worktree_access();
-    let new_commit = amend_diff_specs(ctx, diff_specs, stack_id, *oid, guard.write_permission())?
-        .new_commit
-        .map(|c| {
-            let s = c.to_string();
-            format!("{}{}", s[..2].blue().underline(), s[2..7].blue())
-        })
-        .unwrap_or_default();
+    let outcome = amend_diff_specs(ctx, diff_specs, stack_id, *oid, guard.write_permission())?;
     if let Some(out) = out.for_human() {
+        let new_commit = outcome
+            .new_commit
+            .map(|c| {
+                let s = c.to_string();
+                format!("{}{}", s[..2].blue().underline(), s[2..7].blue())
+            })
+            .unwrap_or_default();
         writeln!(out, "Amended {} → {}", description, new_commit)?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({
+            "ok": true,
+            "newCommitId": outcome.new_commit.map(|c| c.to_string()),
+        }))?;
     }
     Ok(())
 }
@@ -52,15 +58,15 @@ pub(crate) fn assignments_to_commit(
         .map(|assignment| assignment.into())
         .collect();
     let mut guard = ctx.exclusive_worktree_access();
-    let new_commit = amend_diff_specs(ctx, diff_specs, stack_id, *oid, guard.write_permission())?
-        .new_commit
-        .map(|c| {
-            let s = c.to_string();
-            format!("{}{}", s[..2].blue().underline(), s[2..7].blue())
-        })
-        .unwrap_or_default();
-
+    let outcome = amend_diff_specs(ctx, diff_specs, stack_id, *oid, guard.write_permission())?;
     if let Some(out) = out.for_human() {
+        let new_commit = outcome
+            .new_commit
+            .map(|c| {
+                let s = c.to_string();
+                format!("{}{}", s[..2].blue().underline(), s[2..7].blue())
+            })
+            .unwrap_or_default();
         if let Some(branch_name) = branch_name {
             writeln!(
                 out,
@@ -71,6 +77,11 @@ pub(crate) fn assignments_to_commit(
         } else {
             writeln!(out, "Amended unassigned files → {new_commit}")?;
         }
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({
+            "ok": true,
+            "newCommitId": outcome.new_commit.map(|c| c.to_string()),
+        }))?;
     }
     Ok(())
 }

crates/but/src/command/legacy/rub/assign.rs

@@ -22,6 +22,8 @@ pub(crate) fn assign_uncommitted_to_branch(
     do_assignments(ctx, reqs, out)?;
     if let Some(out) = out.for_human() {
         writeln!(out, "Staged {} → {}.", description, format!("[{branch_name}]").green())?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }
@@ -53,6 +55,8 @@ pub(crate) fn assign_uncommitted_to_stack(
             description,
             format!("[{}]", stack_id).green()
         )?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }
@@ -72,6 +76,8 @@ pub(crate) fn unassign_uncommitted(
     do_assignments(ctx, reqs, out)?;
     if let Some(out) = out.for_human() {
         writeln!(out, "Unstaged {description}")?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }
@@ -163,6 +169,8 @@ fn assign_all_inner(
                     .unwrap_or_else(|| "unstaged".to_string().bold())
             )?;
         }
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }

crates/but/src/command/legacy/rub/commits.rs

@@ -34,6 +34,8 @@ pub fn commited_file_to_another_commit(
 
     if let Some(out) = out.for_human() {
         writeln!(out, "Moved files between commits!")?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
 
     Ok(())
@@ -73,6 +75,8 @@ pub fn uncommit_file(
 
     if let Some(out) = out.for_human() {
         writeln!(out, "Uncommitted changes")?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
 
     Ok(())

crates/but/src/command/legacy/rub/move.rs

@@ -249,6 +249,16 @@ fn move_to_commit(
                 "     {} Reposition to the desired location (use the new commit ID from step 1)",
                 "↳".cyan()
             )?;
+        } else if let Some(out) = out.for_json() {
+            out.write_value(serde_json::json!({
+                "ok": false,
+                "error": "cross_stack_position",
+                "hint": format!(
+                    "Move to branch first with 'but move {} {}', then reposition",
+                    &source_oid.to_string()[..7],
+                    target_stack_head_branch
+                ),
+            }))?;
         }
 
         bail!("Cannot move commit to specific position in another stack");
@@ -311,14 +321,16 @@ fn move_to_branch(
                 let cmd = format!("but move {} <target-commit> [--after]", &source_str[..7]);
                 writeln!(out, "  {}", cmd.green())?;
             }
+        } else if let Some(out) = out.for_json() {
+            out.write_value(serde_json::json!({"ok": true}))?;
         }
     } else {
         // Different stack - use move_commit API
         if let Some(illegal_move) =
             gitbutler_branch_actions::move_commit(ctx, target_stack_id, source_oid.to_git2(), source_stack_id)?
         {
             if let Some(out) = out.for_human() {
-                match illegal_move {
+                match &illegal_move {
                     gitbutler_branch_actions::MoveCommitIllegalAction::DependsOnCommits(deps) => {
                         writeln!(
                             out,
@@ -343,6 +355,24 @@ fn move_to_branch(
                         )?;
                     }
                 }
+            } else if let Some(out) = out.for_json() {
+                let (reason, deps) = match &illegal_move {
+                    gitbutler_branch_actions::MoveCommitIllegalAction::DependsOnCommits(deps) => {
+                        ("depends_on_commits", Some(deps.clone()))
+                    }
+                    gitbutler_branch_actions::MoveCommitIllegalAction::HasDependentChanges(deps) => {
+                        ("has_dependent_changes", Some(deps.clone()))
+                    }
+                    gitbutler_branch_actions::MoveCommitIllegalAction::HasDependentUncommittedChanges => {
+                        ("has_dependent_uncommitted_changes", None)
+                    }
+                };
+                out.write_value(serde_json::json!({
+                    "ok": false,
+                    "error": "illegal_move",
+                    "reason": reason,
+                    "dependencies": deps,
+                }))?;
             }
             bail!("Illegal move");
         }
@@ -371,6 +401,8 @@ fn move_to_branch(
                 let cmd = format!("but move {} <target-commit> [--after]", &source_str[..7]);
                 writeln!(out, "  {}", cmd.green())?;
             }
+        } else if let Some(out) = out.for_json() {
+            out.write_value(serde_json::json!({"ok": true}))?;
         }
     }
 
@@ -415,6 +447,8 @@ fn move_within_stack(
     if git2_source_oid == git2_target_oid {
         if let Some(out) = out.for_human() {
             writeln!(out, "Source and target are the same commit. Nothing to do.")?;
+        } else if let Some(out) = out.for_json() {
+            out.write_value(serde_json::json!({"ok": true}))?;
         }
         return Ok(());
     }
@@ -457,6 +491,8 @@ fn move_within_stack(
             position_desc,
             target_oid.to_string()[..7].blue()
         )?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
 
     Ok(())

crates/but/src/command/legacy/rub/move_commit.rs

@@ -34,7 +34,7 @@ pub(crate) fn to_branch(
         gitbutler_branch_actions::move_commit(ctx, target_stack_id, oid.to_git2(), source_stack_id)?
     {
         if let Some(out) = out.for_human() {
-            match illegal_move {
+            match &illegal_move {
                 gitbutler_branch_actions::MoveCommitIllegalAction::DependsOnCommits(deps) => {
                     writeln!(
                         out,
@@ -58,6 +58,24 @@ pub(crate) fn to_branch(
                     )
                 }
             }?;
+        } else if let Some(out) = out.for_json() {
+            let (reason, deps) = match &illegal_move {
+                gitbutler_branch_actions::MoveCommitIllegalAction::DependsOnCommits(deps) => {
+                    ("depends_on_commits", Some(deps.clone()))
+                }
+                gitbutler_branch_actions::MoveCommitIllegalAction::HasDependentChanges(deps) => {
+                    ("has_dependent_changes", Some(deps.clone()))
+                }
+                gitbutler_branch_actions::MoveCommitIllegalAction::HasDependentUncommittedChanges => {
+                    ("has_dependent_uncommitted_changes", None)
+                }
+            };
+            out.write_value(serde_json::json!({
+                "ok": false,
+                "error": "illegal_move",
+                "reason": reason,
+                "dependencies": deps,
+            }))?;
         }
         bail!("Illegal move")
     }
@@ -68,6 +86,8 @@ pub(crate) fn to_branch(
             oid.to_string()[..7].blue(),
             format!("[{branch_name}]").green()
         )?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }

crates/but/src/command/legacy/rub/squash.rs

@@ -256,6 +256,12 @@ fn squash_commits_internal(
                 final_commit_oid.to_gix().to_string()[..7].blue()
             )?
         }
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({
+            "ok": true,
+            "newCommitId": final_commit_oid.to_gix().to_string(),
+            "squashedCount": source_oids.len(),
+        }))?;
     }
     Ok(())
 }

crates/but/src/command/legacy/rub/undo.rs

@@ -10,6 +10,8 @@ pub(crate) fn commit(ctx: &mut Context, oid: &ObjectId, out: &mut OutputChannel)
     gitbutler_branch_actions::undo_commit(ctx, stack_id_by_commit_id(ctx, oid)?, oid.to_git2())?;
     if let Some(out) = out.for_human() {
         writeln!(out, "Uncommitted {}", oid.to_string()[..7].blue())?;
+    } else if let Some(out) = out.for_json() {
+        out.write_value(serde_json::json!({"ok": true}))?;
     }
     Ok(())
 }