fix(ghook): stop double-emitting Claude PreToolUse denies [project-#147]

For --cli=claude, narrow the legacy stderr+exit(2) channel to
responses that explicitly set top-level continue:false with a
non-empty stopReason (the HARD_STOP shape). All other responses --
including PreToolUse denies that arrive via
hookSpecificOutput.permissionDecision:"deny" -- now go to stdout
JSON + exit 0, matching the contract the Python ClaudeCodeAdapter
already targets (PRE_TOOL_USE is in
DECISION_STYLES_ALLOWED_TO_CONTINUE_ON_DENY, so the daemon never
adds the second channel itself).

Previously ghook synthesized a second deny channel on top of the
structured one, so Claude rendered every PreToolUse deny twice --
once as a permission denial, once as a "hook blocking error".

Codex/Gemini/Qwen/Droid paths are unchanged; their is_blocked
contract still flows through the legacy tail of
action_from_success_response.

Bumps crates/ghook to 0.4.1; renames the unreleased CHANGELOG
section in place; updates ghook docs version refs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: joshwilhelmi

CHANGELOG.md

@@ -7,7 +7,7 @@ All notable changes to gobby-cli are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [0.4.0] — gobby-hooks
+## [0.4.1] — gobby-hooks
 
 ### Added
 
@@ -22,6 +22,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - **Droid blocking semantics** — droid daemon responses with `continue:false` now exit 2 with the daemon reason while preserving the response JSON on stdout. Other droid block JSON is forwarded on stdout with exit 0 for droid's hook protocol, and daemon transport failures surface as exit 1 stderr diagnostics.
 
+### Fixed
+
+#### gobby-hooks
+
+- **Stop double-emitting Claude PreToolUse denies** — for `--cli=claude`, ghook now narrows the legacy `stderr+exit(2)` channel to daemon responses that explicitly set top-level `continue:false` with a non-empty `stopReason` (the HARD_STOP shape). All other responses — including PreToolUse denies that arrive via `hookSpecificOutput.permissionDecision:"deny"` — are emitted as JSON on stdout with exit 0, matching the structured-channel contract the Python `ClaudeCodeAdapter` already targets. Previously, ghook synthesized a second deny channel on top of the structured one, causing Claude Code to render every PreToolUse deny twice (once as a permission denial, once as a "hook blocking error"). Codex/Gemini/Qwen/Droid paths are unchanged.
+
 ## [0.3.1] — gobby-hooks
 
 ### Added

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "gobby-hooks"
-version = "0.4.0"
+version = "0.4.1"
 edition = "2024"
 rust-version = "1.85"
 authors = ["Josh Wilhelmi <hello@gobby.ai>"]

crates/ghook/Cargo.toml

@@ -323,6 +323,35 @@ fn action_from_success_response(
         return Ok(action_from_droid_success(result, serialized));
     }
 
+    // Claude carries a structured permissionDecision channel; emitting a
+    // second stderr+exit(2) channel on top makes Claude render every
+    // PreToolUse deny twice. Mirror the daemon contract: only the
+    // top-level continue:false + stopReason shape (HARD_STOP) becomes
+    // exit 2. Codex/Gemini/Qwen keep the legacy is_blocked path below.
+    if canonical_source == "claude" {
+        let map = result.as_object();
+        let continue_false =
+            map.and_then(|m| m.get("continue")).and_then(Value::as_bool) == Some(false);
+        let stop_reason = map
+            .and_then(|m| m.get("stopReason"))
+            .and_then(Value::as_str)
+            .filter(|s| !s.is_empty());
+
+        if continue_false && let Some(reason) = stop_reason {
+            return Ok(HookAction {
+                exit_code: 2,
+                stdout_json: None,
+                stderr_message: Some(reason.to_string()),
+            });
+        }
+
+        return Ok(HookAction {
+            exit_code: 0,
+            stdout_json: json_value_is_meaningful(&result).then_some(serialized),
+            stderr_message: None,
+        });
+    }
+
     if is_blocked(&result) {
         if hook_type != "Stop" {
             return Ok(HookAction {
@@ -644,6 +673,48 @@ mod tests {
         );
     }
 
+    #[test]
+    fn action_from_success_claude_hard_stop_exits_two() {
+        let action = action_from_success_response(
+            "claude",
+            "Stop",
+            r#"{"continue":false,"stopReason":"Daemon halted run"}"#,
+        )
+        .unwrap();
+
+        assert_eq!(
+            action,
+            HookAction {
+                exit_code: 2,
+                stdout_json: None,
+                stderr_message: Some("Daemon halted run".to_string()),
+            }
+        );
+    }
+
+    #[test]
+    fn action_from_success_claude_stop_with_permission_deny_no_exit_two() {
+        let action = action_from_success_response(
+            "claude",
+            "Stop",
+            r#"{"hookSpecificOutput":{"permissionDecision":"deny","permissionDecisionReason":"r"}}"#,
+        )
+        .unwrap();
+
+        assert_eq!(action.exit_code, 0);
+        assert!(action.stdout_json.is_some());
+        assert_eq!(action.stderr_message, None);
+    }
+
+    #[test]
+    fn action_from_success_claude_continue_false_without_reason_does_not_exit_two() {
+        let action =
+            action_from_success_response("claude", "Stop", r#"{"continue":false}"#).unwrap();
+
+        assert_eq!(action.exit_code, 0);
+        assert_eq!(action.stderr_message, None);
+    }
+
     #[test]
     fn action_from_success_treats_droid_continue_false_as_exit_two_with_json() {
         let action = action_from_success_response(

crates/ghook/src/main.rs

@@ -152,8 +152,8 @@ Schema:
 ```json
 {
   "install_method": "github-release",
-  "install_source_url": "https://github.com/GobbyAI/gobby-cli/releases/download/ghook-v0.4.0/ghook-aarch64-apple-darwin.tar.gz",
-  "installed_version": "0.4.0",
+  "install_source_url": "https://github.com/GobbyAI/gobby-cli/releases/download/ghook-v0.4.1/ghook-aarch64-apple-darwin.tar.gz",
+  "installed_version": "0.4.1",
   "installed_at": "2026-04-22T18:30:00Z"
 }
 ```
@@ -318,7 +318,7 @@ Almost always config-only. ghook treats `--type` as opaque. To make a hook criti
 
 ## Versioning
 
-ghook is at `0.4.0`. The envelope `SCHEMA_VERSION` is `1`; the diagnose-output schema is `2`. The three version numbers are independent:
+ghook is at `0.4.1`. The envelope `SCHEMA_VERSION` is `1`; the diagnose-output schema is `2`. The three version numbers are independent:
 
 - **Crate version** bumps for any code change (binary behavior, dependencies, perf, etc.).
 - **Envelope `SCHEMA_VERSION`** bumps only when the inbox envelope shape changes in a way the daemon must explicitly handle.

docs/guides/ghook-development-guide.md

@@ -162,7 +162,7 @@ Unknown `--cli` values fall back to conservative Claude-like dispatch behavior o
 $ ghook --diagnose --cli=claude --type=session-start
 {
   "schema_version": 2,
-  "ghook_version": "0.4.0",
+  "ghook_version": "0.4.1",
   "cli": "claude",
   "hook_type": "session-start",
   "source": "claude",
@@ -182,7 +182,7 @@ $ ghook --diagnose --cli=claude --type=session-start
   },
   "cli_recognized": true,
   "install_method": "github-release",
-  "install_source_url": "https://github.com/GobbyAI/gobby-cli/releases/download/ghook-v0.4.0/ghook-aarch64-apple-darwin.tar.gz"
+  "install_source_url": "https://github.com/GobbyAI/gobby-cli/releases/download/ghook-v0.4.1/ghook-aarch64-apple-darwin.tar.gz"
 }
 ```