fix: escape credential.helper path so git-credential-nostr survives spaces

desktop/src-tauri/src/commands/project_git_exec.rs

@@ -185,9 +185,11 @@ fn configure_git_auth(command: &mut Command, auth: &GitAuthConfig, needs_credent
 /// Format a path for git `credential.helper`.
 ///
 /// Git for Windows invokes helpers via MinGW bash, which treats `\` as
-/// escapes. Forward slashes work on every platform git supports.
+/// escapes, so paths are normalized to forward slashes first. The result is
+/// then shell-escaped — see `git_credential_helper_config_value` for why a
+/// naive whole-value quote doesn't work.
 fn credential_helper_config_value(path: &std::path::Path) -> String {
-    path.to_string_lossy().replace('\\', "/")
+    crate::managed_agents::git_credential_helper_config_value(path)
 }
 
 fn apply_git_config(command: &mut Command, entries: &[(&str, String)]) {
@@ -341,6 +343,24 @@ mod tests {
         );
     }
 
+    #[test]
+    fn credential_helper_config_value_escapes_spaces() {
+        let path = std::path::PathBuf::from("/Users/x/My Apps/git-credential-nostr");
+        assert_eq!(
+            credential_helper_config_value(&path),
+            r"/Users/x/My\ Apps/git-credential-nostr",
+        );
+    }
+
+    #[test]
+    fn credential_helper_config_value_escapes_apostrophes() {
+        let path = std::path::PathBuf::from("/Users/o'brien/git-credential-nostr");
+        assert_eq!(
+            credential_helper_config_value(&path),
+            r"/Users/o\'brien/git-credential-nostr",
+        );
+    }
+
     #[test]
     fn git_subcommand_skips_global_config_options() {
         assert_eq!(

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -590,6 +590,29 @@ pub fn resolve_command(command: &str) -> Option<PathBuf> {
     result
 }
 
+/// Escape a path for use as a git `credential.helper` config value.
+///
+/// Git builds the helper command by concatenating the raw `credential.helper`
+/// string with an operation (`get`/`store`/`erase`) and running the result
+/// through `sh -c`, so any shell metacharacter in the path (most commonly a
+/// space) gets word-split and breaks the invocation. Git also detects an
+/// absolute-path helper by checking whether the *unescaped* string starts
+/// with a path separator (or drive letter on Windows) — quoting the value as
+/// a whole hides that leading character and git falls back to treating it as
+/// a bare helper name instead. So each shell-special character is escaped
+/// individually with a backslash, leaving the leading separator intact.
+pub fn git_credential_helper_config_value(path: &std::path::Path) -> String {
+    let normalized = path.to_string_lossy().replace('\\', "/");
+    let mut escaped = String::with_capacity(normalized.len());
+    for ch in normalized.chars() {
+        if !(ch.is_ascii_alphanumeric() || matches!(ch, '-' | '_' | '.' | '/' | ':')) {
+            escaped.push('\\');
+        }
+        escaped.push(ch);
+    }
+    escaped
+}
+
 /// Clear the resolve_command cache so that newly-installed binaries are detected.
 pub fn clear_resolve_cache() {
     let mut guard = resolve_cache().lock().unwrap_or_else(|e| e.into_inner());

desktop/src-tauri/src/managed_agents/runtime.rs

@@ -6,10 +6,10 @@ use super::agent_env::build_buzz_agent_provider_defaults;
 
 use crate::{
     managed_agents::{
-        append_log_marker, known_acp_runtime, login_shell_path, managed_agent_log_path,
-        missing_command_message, normalize_agent_args, open_log_file, resolve_command,
-        spawn_key_refusal, KnownAcpRuntime, ManagedAgentPairRuntime, ManagedAgentRecord,
-        ManagedAgentRuntimeKey, ManagedAgentSummary,
+        append_log_marker, git_credential_helper_config_value, known_acp_runtime, login_shell_path,
+        managed_agent_log_path, missing_command_message, normalize_agent_args, open_log_file,
+        resolve_command, spawn_key_refusal, KnownAcpRuntime, ManagedAgentPairRuntime,
+        ManagedAgentRecord, ManagedAgentRuntimeKey, ManagedAgentSummary,
     },
     util::now_iso,
 };
@@ -835,8 +835,10 @@ pub fn spawn_agent_child(
             "GIT_CONFIG_KEY_0",
             format!("credential.{relay_http_url}/git.helper"),
         );
-        let helper = cred_helper.to_string_lossy().replace('\\', "/");
-        command.env("GIT_CONFIG_VALUE_0", helper);
+        command.env(
+            "GIT_CONFIG_VALUE_0",
+            git_credential_helper_config_value(&cred_helper),
+        );
         command.env(
             "GIT_CONFIG_KEY_1",
             format!("credential.{relay_http_url}/git.useHttpPath"),