feat: add --edit session flag to edit conversation before forking

crates/goose-cli/src/cli.rs

@@ -874,6 +874,15 @@ enum Command {
         )]
         fork: bool,
 
+        /// Open the session's conversation in $EDITOR before starting
+        #[arg(
+            long,
+            requires = "resume",
+            help = "Edit the session conversation in $EDITOR before starting",
+            long_help = "Open the session's conversation in your editor ($VISUAL / $EDITOR / vi) for modification before resuming. When combined with --fork, creates a new session from the edited result."
+        )]
+        edit: bool,
+
         /// Show message history when resuming
         #[arg(
             long,
@@ -1465,6 +1474,7 @@ async fn handle_interactive_session(
     identifier: Option<Identifier>,
     resume: bool,
     fork: bool,
+    edit: bool,
     history: bool,
     session_opts: SessionOptions,
     extension_opts: ExtensionOptions,
@@ -1504,12 +1514,31 @@ async fn handle_interactive_session(
     let goose_mode = Config::global().get_goose_mode().unwrap_or_default();
     let mut session_id = get_or_create_session_id(identifier, resume, false, goose_mode).await?;
 
-    if fork {
-        if let Some(id) = session_id {
+    if edit || fork {
+        if let Some(ref id) = session_id {
             let session_manager = SessionManager::instance();
-            let original = session_manager.get_session(&id, false).await?;
-            let copied = session_manager.copy_session(&id, original.name).await?;
-            session_id = Some(copied.id);
+            let original = session_manager.get_session(id, true).await?;
+
+            let target_id = if fork {
+                let copied = session_manager
+                    .copy_session(id, original.name.clone())
+                    .await?;
+                let copied_id = copied.id.clone();
+                session_id = Some(copied.id);
+                copied_id
+            } else {
+                id.clone()
+            };
+
+            if edit {
+                let conversation = original
+                    .conversation
+                    .ok_or_else(|| anyhow::anyhow!("session has no messages to edit"))?;
+                let edited = crate::session::editor::edit_conversation(&conversation)?;
+                session_manager
+                    .replace_conversation(&target_id, &edited)
+                    .await?;
+            }
         }
     }
 
@@ -2081,6 +2110,7 @@ pub async fn cli() -> anyhow::Result<()> {
             identifier,
             resume,
             fork,
+            edit,
             history,
             session_opts,
             extension_opts,
@@ -2089,6 +2119,7 @@ pub async fn cli() -> anyhow::Result<()> {
                 identifier,
                 resume,
                 fork,
+                edit,
                 history,
                 session_opts,
                 extension_opts,

crates/goose-cli/src/session/editor.rs

@@ -1,7 +1,10 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use goose::config::Config;
+use goose::conversation::message::Message;
+use goose::conversation::Conversation;
 use std::fs;
 use std::io::Read;
+use std::io::Write;
 use std::path::PathBuf;
 use std::process::Command;
 use tempfile::Builder;
@@ -21,9 +24,6 @@ pub fn resolve_editor_command() -> Option<String> {
     )
 }
 
-/// Inner resolution logic, separated for testability.
-/// Checks sources in priority order: config, VISUAL, EDITOR.
-/// Skips empty strings at each level.
 fn resolve_editor_from_sources(
     config_editor: Option<&str>,
     visual: Option<&str>,
@@ -37,6 +37,57 @@ fn resolve_editor_from_sources(
     None
 }
 
+/// Resolve the editor command, falling back to vi (or notepad on Windows).
+pub fn resolve_editor_or_default() -> String {
+    let config = Config::global();
+    let config_editor = config.get_goose_prompt_editor().ok().flatten();
+    let visual = std::env::var("VISUAL").ok();
+    let editor_env = std::env::var("EDITOR").ok();
+    resolve_editor_or_default_from_sources(
+        config_editor.as_deref(),
+        visual.as_deref(),
+        editor_env.as_deref(),
+    )
+}
+
+fn resolve_editor_default() -> String {
+    if cfg!(windows) {
+        "notepad".to_string()
+    } else {
+        "vi".to_string()
+    }
+}
+
+fn resolve_editor_or_default_from_sources(
+    config_editor: Option<&str>,
+    visual: Option<&str>,
+    editor_env: Option<&str>,
+) -> String {
+    resolve_editor_from_sources(config_editor, visual, editor_env)
+        .unwrap_or_else(resolve_editor_default)
+}
+
+/// Open a YAML temp file with the user's editor to edit a conversation.
+/// Returns the edited conversation, or an error if the editor failed or YAML was invalid.
+pub fn edit_conversation(conversation: &Conversation) -> Result<Conversation> {
+    let yaml = serde_yaml::to_string(conversation.messages())?;
+
+    let mut tmp = NamedTempFile::with_suffix(".yaml")?;
+    tmp.write_all(yaml.as_bytes())?;
+    tmp.flush()?;
+
+    let editor = resolve_editor_or_default();
+    let path = tmp.path().to_path_buf();
+
+    launch_editor(&editor, &path).with_context(|| format!("failed to launch editor '{editor}'"))?;
+
+    let edited = std::fs::read_to_string(&path)?;
+    let messages: Vec<Message> =
+        serde_yaml::from_str(&edited).context("invalid YAML — session unchanged")?;
+
+    Ok(Conversation::new_unvalidated(messages))
+}
+
 /// Build the markdown template content for the editor prompt.
 fn build_template(messages: &[&str], prefill: Option<&str>) -> String {
     let mut content = String::from("# Goose Prompt Editor\n\n");
@@ -84,21 +135,36 @@ impl SymlinkCleanup {
 
 impl Drop for SymlinkCleanup {
     fn drop(&mut self) {
-        // Always try to clean up the symlink, ignoring any errors
         let _ = std::fs::remove_file(&self.symlink_path);
     }
 }
 
+/// Split an editor command into program and arguments.
+///
+/// Uses shell-word splitting only when the command contains quotes, so values like
+/// `"/Applications/Sublime Text.app/.../subl" -w` work. Unquoted commands are split on
+/// whitespace to avoid shlex stripping backslashes from Windows paths like
+/// `C:\Windows\System32\notepad.exe`.
+fn split_editor_command(editor_cmd: &str) -> Result<Vec<String>> {
+    if editor_cmd.contains(['"', '\'']) {
+        shlex::split(editor_cmd).ok_or_else(|| {
+            anyhow::anyhow!("Invalid editor command: unmatched quotes in '{editor_cmd}'")
+        })
+    } else {
+        Ok(editor_cmd.split_whitespace().map(String::from).collect())
+    }
+}
+
 /// Launch editor and wait for completion
 fn launch_editor(editor_cmd: &str, file_path: &PathBuf) -> Result<()> {
     use std::process::Stdio;
 
-    let parts: Vec<&str> = editor_cmd.split_whitespace().collect();
+    let parts = split_editor_command(editor_cmd)?;
     if parts.is_empty() {
         return Err(anyhow::anyhow!("Empty editor command"));
     }
 
-    let mut cmd = Command::new(parts[0]);
+    let mut cmd = Command::new(&parts[0]);
     if let Ok(cwd) = std::env::current_dir() {
         cmd.current_dir(cwd);
     }
@@ -414,64 +480,72 @@ with multiple lines.
         );
     }
 
-    // --- resolve_editor_from_sources tests ---
-
     #[test]
-    fn test_resolve_editor_returns_config_when_set() {
-        let result = resolve_editor_from_sources(Some("code"), Some("vim"), Some("nano"));
-        assert_eq!(result.as_deref(), Some("code"));
-    }
+    fn test_resolve_editor_resolution_priority() {
+        assert_eq!(
+            resolve_editor_from_sources(Some("config-val"), Some("visual-val"), Some("editor-val")),
+            Some("config-val".to_string())
+        );
 
-    #[test]
-    fn test_resolve_editor_falls_back_to_visual() {
-        let result = resolve_editor_from_sources(None, Some("vim"), Some("nano"));
-        assert_eq!(result.as_deref(), Some("vim"));
-    }
+        assert_eq!(
+            resolve_editor_from_sources(Some(""), Some("visual-val"), Some("editor-val")),
+            Some("visual-val".to_string())
+        );
 
-    #[test]
-    fn test_resolve_editor_falls_back_to_editor_env() {
-        let result = resolve_editor_from_sources(None, None, Some("nano"));
-        assert_eq!(result.as_deref(), Some("nano"));
-    }
+        assert_eq!(
+            resolve_editor_from_sources(None, Some(""), Some("editor-val")),
+            Some("editor-val".to_string())
+        );
 
-    #[test]
-    fn test_resolve_editor_returns_none_when_nothing_set() {
-        let result = resolve_editor_from_sources(None, None, None);
-        assert_eq!(result, None);
-    }
+        assert_eq!(resolve_editor_from_sources(None, None, None), None);
+        assert_eq!(
+            resolve_editor_from_sources(Some(""), Some(""), Some("")),
+            None
+        );
 
-    #[test]
-    fn test_resolve_editor_skips_empty_config() {
-        let result = resolve_editor_from_sources(Some(""), Some("vim"), None);
-        assert_eq!(result.as_deref(), Some("vim"));
+        let default_val = resolve_editor_default();
+        assert_eq!(
+            resolve_editor_or_default_from_sources(None, None, None),
+            default_val
+        );
+        assert_eq!(
+            resolve_editor_or_default_from_sources(Some(""), Some(""), Some("")),
+            default_val
+        );
     }
 
     #[test]
-    fn test_resolve_editor_skips_empty_visual() {
-        let result = resolve_editor_from_sources(None, Some(""), Some("nano"));
-        assert_eq!(result.as_deref(), Some("nano"));
-    }
+    fn test_split_editor_command() {
+        assert_eq!(
+            split_editor_command("code --wait").unwrap(),
+            vec!["code", "--wait"]
+        );
 
-    #[test]
-    fn test_resolve_editor_skips_all_empty() {
-        let result = resolve_editor_from_sources(Some(""), Some(""), Some(""));
-        assert_eq!(result, None);
-    }
+        assert_eq!(
+            split_editor_command(
+                r#""/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" -w"#
+            )
+            .unwrap(),
+            vec![
+                "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl",
+                "-w"
+            ]
+        );
 
-    #[test]
-    fn test_resolve_editor_skips_empty_config_and_visual() {
-        let result = resolve_editor_from_sources(Some(""), Some(""), Some("emacs"));
-        assert_eq!(result.as_deref(), Some("emacs"));
+        assert_eq!(
+            split_editor_command(r"C:\Windows\System32\notepad.exe").unwrap(),
+            vec![r"C:\Windows\System32\notepad.exe"]
+        );
+
+        assert!(split_editor_command(r#"code --wait "unclosed"#).is_err());
     }
 
     // --- build_template edge case tests ---
 
     #[test]
     fn test_build_template_empty_prefill_string() {
         let content = build_template(&["## User: Hello"], Some(""));
-        // Empty prefill should not appear in content
         assert!(content.contains("# Your prompt:\n\n#"));
-        // Should go directly to conversation context
         assert!(content.contains("# Recent conversation for context"));
     }
 
@@ -498,19 +572,15 @@ with multiple lines.
         assert!(prefill_pos < context_pos);
     }
 
-    // --- extract_user_input with prefilled content tests ---
-
     #[test]
     fn test_extract_user_input_with_prefill_kept() {
-        // Simulates a user who opened the editor with prefill and kept it unchanged
         let content = build_template(&["## User: Hello"], Some("fix the login bug"));
         let result = extract_user_input(&content);
         assert_eq!(result, "fix the login bug");
     }
 
     #[test]
     fn test_extract_user_input_with_prefill_edited() {
-        // Simulates a user who edited the prefill text
         let mut content = build_template(&["## User: Hello"], Some("fix the login bug"));
         content = content.replace(
             "fix the login bug",
@@ -522,7 +592,6 @@ with multiple lines.
 
     #[test]
     fn test_extract_user_input_prefill_replaced() {
-        // Simulates a user who deleted the prefill and wrote something new
         let mut content = build_template(&["## User: Hello"], Some("fix the login bug"));
         content = content.replace("fix the login bug\n", "completely different prompt\n");
         let result = extract_user_input(&content);
@@ -531,7 +600,6 @@ with multiple lines.
 
     #[test]
     fn test_extract_user_input_prefill_cleared() {
-        // Simulates a user who deleted the prefill and left nothing
         let mut content = build_template(&["## User: Hello"], Some("fix the login bug"));
         content = content.replace("fix the login bug\n", "");
         let result = extract_user_input(&content);

crates/goose-cli/src/session/mod.rs

@@ -1,6 +1,6 @@
 mod builder;
 mod completion;
-mod editor;
+pub mod editor;
 mod elicitation;
 mod export;
 mod input;

documentation/docs/guides/goose-cli-commands.md

@@ -206,6 +206,7 @@ Start or resume interactive chat sessions.
 - **`-n, --name <name>`**: Give the session a name
 - **`--path <path>`**: Legacy parameter for specifying session by file path
 - **`-r, --resume`**: Resume a previous session
+- **`--edit`**: Open the session's conversation in your editor (`$VISUAL` / `$EDITOR` / `vi`) as YAML. Edit, trim, or rewrite messages, then save and close to continue the session with the edited conversation. Must be used with `--resume`. Can be combined with `--fork` to create a new session from the edited result.
 - **`--fork`**: Create a new duplicate session with copied history. Must be used with `--resume`. Provide `--name` or `--session-id` to fork a specific session. Otherwise, forks the most recent session.
 - **`--history`**: Show previous messages when resuming a session
 - **`--container <container_id>`**: Run extensions inside a [Docker container](/docs/tutorials/goose-in-docker#running-extensions-in-docker-containers).
@@ -235,6 +236,12 @@ goose session --resume --fork --name my-project
 # Fork the most recent session and show message history
 goose session --resume --fork --history
 
+# Edit a session's conversation in your editor
+goose session --resume --session-id 20251108_2 --edit
+
+# Edit and fork — create a new session from the edited conversation
+goose session --resume --session-id 20251108_2 --fork --edit --history
+
 # Start with extensions
 goose session --with-extension "npx -y @modelcontextprotocol/server-memory"
 goose session --with-builtin developer