# PARITY Gap Analysis Date: 2026-04-01 Scope compared: - Upstream TypeScript: `/home/bellman/Workspace/claude-code/src/` - Rust port: `rust/crates/` Method: - Read-only comparison only. - No upstream source was copied into this repo. - This is a focused feature-gap report for `tools`, `hooks`, `plugins`, `skills`, `cli`, `assistant`, and `services`. ## Executive summary The Rust port has a solid core for: - basic prompt/REPL flow - session/runtime state - Anthropic API/OAuth plumbing - a compact MVP tool registry - CLAUDE.md discovery - MCP config parsing/bootstrap primitives But it is still materially behind the TypeScript implementation in six major areas: 1. **Tools surface area** is much smaller. 2. **Hook execution** is largely missing; Rust mostly loads hook config but does not run a TS-style PreToolUse/PostToolUse pipeline. 3. **Plugins** are effectively absent in Rust. 4. **Skills** are only partially implemented in Rust via direct `SKILL.md` loading; there is no comparable skills command/discovery/registration surface. 5. **CLI** breadth is much narrower in Rust. 6. **Assistant/tool orchestration** lacks the richer streaming concurrency, hook integration, and orchestration behavior present in TS. 7. **Services** in Rust cover API/auth/runtime basics, but many higher-level TS services are missing. ## Critical bug status on this branch Targeted critical items requested by the user: - **Prompt mode tools enabled**: fixed in `rust/crates/rusty-claude-cli/src/main.rs:75-82` - **Default permission mode = danger-full-access**: fixed in `rust/crates/rusty-claude-cli/src/args.rs:12-16`, `rust/crates/rusty-claude-cli/src/main.rs:348-353`, and starter config `rust/crates/rusty-claude-cli/src/init.rs:4-9` - **Tool input `{}` prefix bug**: fixed/guarded in streaming vs non-stream paths at `rust/crates/rusty-claude-cli/src/main.rs:2211-2256` - **Unlimited max_iterations**: already present at `rust/crates/runtime/src/conversation.rs:143-148` with `usize::MAX` initialization at `rust/crates/runtime/src/conversation.rs:119` Build/test/manual verification is tracked separately below and must pass before the branch is considered done. --- ## 1) tools/ ### Upstream TS has - Large per-tool module surface under `src/tools/`, including agent/task tools, AskUserQuestion, MCP tools, plan/worktree tools, REPL, schedule/task tools, synthetic output, brief/upload, and more. - Evidence: - `src/tools/AgentTool/AgentTool.tsx` - `src/tools/AskUserQuestionTool/AskUserQuestionTool.tsx` - `src/tools/ListMcpResourcesTool/ListMcpResourcesTool.ts` - `src/tools/ReadMcpResourceTool/ReadMcpResourceTool.ts` - `src/tools/EnterPlanModeTool/EnterPlanModeTool.ts` - `src/tools/ExitPlanModeTool/ExitPlanModeV2Tool.ts` - `src/tools/EnterWorktreeTool/EnterWorktreeTool.ts` - `src/tools/ExitWorktreeTool/ExitWorktreeTool.ts` - `src/tools/RemoteTriggerTool/RemoteTriggerTool.ts` - `src/tools/ScheduleCronTool/*` - `src/tools/TaskCreateTool/*`, `TaskGetTool/*`, `TaskListTool/*`, `TaskOutputTool/*` ### Rust currently has - A single MVP registry in `rust/crates/tools/src/lib.rs:53-371`. - Implemented tools include `bash`, `read_file`, `write_file`, `edit_file`, `glob_search`, `grep_search`, `WebFetch`, `WebSearch`, `TodoWrite`, `Skill`, `Agent`, `ToolSearch`, `NotebookEdit`, `Sleep`, `SendUserMessage`, `Config`, `StructuredOutput`, `REPL`, `PowerShell`. ### Missing or broken in Rust - **Missing large chunks of the upstream tool catalog**: I did not find Rust equivalents for AskUserQuestion, MCP resource listing/reading tools, plan/worktree entry/exit tools, task management tools, remote trigger, synthetic output, or schedule/cron tools. - **Tool decomposition is much coarser**: TS isolates tool-specific validation/security/UI behavior per tool module; Rust centralizes almost everything in one file (`rust/crates/tools/src/lib.rs`). - **Likely parity impact**: lower fidelity tool prompting, weaker per-tool behavior specialization, and fewer native tool choices exposed to the model. --- ## 2) hooks/ ### Upstream TS has - A full permission and tool-hook system with **PermissionRequest**, **PreToolUse**, **PostToolUse**, and failure/cancellation handling. - Evidence: - `src/hooks/toolPermission/PermissionContext.ts:25,222` - `src/hooks/toolPermission/handlers/coordinatorHandler.ts:32-38` - `src/hooks/toolPermission/handlers/interactiveHandler.ts:412-429` - `src/services/tools/toolHooks.ts:39,435` - `src/services/tools/toolExecution.ts:800,1074,1483` - `src/commands/hooks/index.ts:5-8` ### Rust currently has - Hook data is **loaded/merged from config** and visible in reports: - `rust/crates/runtime/src/config.rs:786-797,829-838` - `rust/crates/rusty-claude-cli/src/main.rs:1665-1669` - The system prompt acknowledges user-configured hooks: - `rust/crates/runtime/src/prompt.rs:452-459` ### Missing or broken in Rust - **No comparable hook execution pipeline found** in the Rust runtime conversation/tool execution path. - `rust/crates/runtime/src/conversation.rs:151-208` goes straight from assistant tool_use -> permission check -> tool execute -> tool_result, without TS-style PreToolUse/PostToolUse processing. - I did **not** find Rust counterparts to TS files like `toolHooks.ts` or `PermissionContext.ts` that execute hook callbacks and alter/block tool behavior. - Result: Rust appears to support **hook configuration visibility**, but not full **hook behavior parity**. --- ## 3) plugins/ ### Upstream TS has - Built-in and bundled plugin registration plus CLI/service support for validate/list/install/uninstall/enable/disable/update flows. - Evidence: - `src/plugins/builtinPlugins.ts:7-17,149-150` - `src/plugins/bundled/index.ts:7-22` - `src/cli/handlers/plugins.ts:51,101,157,668` - `src/services/plugins/pluginOperations.ts:16,54,306,435,713` - `src/services/plugins/pluginCliCommands.ts:7,36` ### Rust currently has - I did **not** find a dedicated plugin crate/module/handler under `rust/crates/`. - The Rust crate layout is only `api`, `commands`, `compat-harness`, `runtime`, `rusty-claude-cli`, and `tools`. ### Missing or broken in Rust - **Plugin loading/install/update/validation is missing.** - **No plugin CLI surface found** comparable to `claude plugin ...`. - **No plugin runtime refresh/reconciliation layer found**. - This is one of the largest parity gaps. --- ## 4) skills/ ### Upstream TS has - Bundled skills registry and loader integration, plus a `skills` command. - Evidence: - `src/commands/skills/index.ts:6` - `src/skills/bundledSkills.ts:44,99,107,114` - `src/skills/loadSkillsDir.ts:65` - `src/skills/mcpSkillBuilders.ts:4-21,40` ### Rust currently has - A `Skill` tool that loads local `SKILL.md` files directly: - `rust/crates/tools/src/lib.rs:1244-1255` - `rust/crates/tools/src/lib.rs:1288-1323` - CLAUDE.md / instruction discovery exists in runtime prompt loading: - `rust/crates/runtime/src/prompt.rs:203-208` ### Missing or broken in Rust - **No Rust `/skills` slash command** in `rust/crates/commands/src/lib.rs:41-166`. - **No visible bundled-skill registry equivalent** to TS `bundledSkills.ts` / `loadSkillsDir.ts` / `mcpSkillBuilders.ts`. - Current Rust skill support is closer to **direct file loading** than full upstream **skill discovery/registration/command integration**. --- ## 5) cli/ ### Upstream TS has - Broad CLI handler and transport surface. - Evidence: - `src/cli/handlers/agents.ts:2-32` - `src/cli/handlers/auth.ts` - `src/cli/handlers/autoMode.ts:24,35,73` - `src/cli/handlers/plugins.ts:2-3,101,157,668` - `src/cli/remoteIO.ts:25-35,118-127` - `src/cli/transports/SSETransport.ts` - `src/cli/transports/WebSocketTransport.ts` - `src/cli/transports/HybridTransport.ts` - `src/cli/transports/SerialBatchEventUploader.ts` - `src/cli/transports/WorkerStateUploader.ts` ### Rust currently has - Minimal top-level subcommands in `rust/crates/rusty-claude-cli/src/args.rs:29-39` and `rust/crates/rusty-claude-cli/src/main.rs:67-90,242-261`. - Slash command surface is 15 commands total in `rust/crates/commands/src/lib.rs:41-166,389`. ### Missing or broken in Rust - **Missing major CLI subcommand families**: agents, plugins, mcp management, auto-mode tooling, and many other TS commands. - **Missing remote/transport stack parity**: I did not find Rust equivalents to TS remote structured IO / SSE / websocket / CCR transport layers. - **Slash command breadth is much narrower** than TS command inventory under `src/commands/`. - **Prompt-mode parity bug** was present and is now fixed for this branch’s prompt path. --- ## 6) assistant/ ### Upstream TS has - Rich tool orchestration and streaming execution behavior, including concurrency/cancellation/fallback logic. - Evidence: - `src/services/tools/StreamingToolExecutor.ts:35-214` - `src/services/tools/toolExecution.ts:455-569,800-918,1483` - `src/services/tools/toolOrchestration.ts:134-167` - `src/assistant/sessionHistory.ts` ### Rust currently has - A straightforward agentic loop in `rust/crates/runtime/src/conversation.rs:130-214`. - Streaming API adaptation in `rust/crates/rusty-claude-cli/src/main.rs:1998-2058`. - Tool-use block assembly and non-stream fallback handling in `rust/crates/rusty-claude-cli/src/main.rs:2211-2256`. ### Missing or broken in Rust - **No TS-style streaming tool executor** with sibling cancellation / fallback discard semantics. - **No integrated PreToolUse/PostToolUse hook participation** in assistant execution. - **No comparable orchestration layer for richer tool event semantics** found. - Historically broken parity items in prompt mode were: - prompt tool enablement (`main.rs:75-82`) — now fixed on this branch - streamed `{}` tool-input prefix behavior (`main.rs:2211-2256`) — now fixed/guarded on this branch --- ## 7) services/ ### Upstream TS has - Very broad service layer, including API, analytics, compact/session memory, prompt suggestions, plugin services, MCP service helpers, LSP management, policy limits, team memory sync, notifier/tips, etc. - Evidence: - `src/services/api/client.ts`, `src/services/api/claude.ts`, `src/services/api/withRetry.ts` - `src/services/oauth/client.ts`, `src/services/oauth/index.ts` - `src/services/mcp/*` - `src/services/plugins/*` - `src/services/lsp/*` - `src/services/compact/*` - `src/services/SessionMemory/*` - `src/services/PromptSuggestion/*` - `src/services/analytics/*` - `src/services/teamMemorySync/*` ### Rust currently has - Core service equivalents for: - API client + SSE: `rust/crates/api/src/client.rs`, `rust/crates/api/src/sse.rs`, `rust/crates/api/src/types.rs` - OAuth: `rust/crates/runtime/src/oauth.rs` - MCP config/bootstrap primitives: `rust/crates/runtime/src/mcp.rs`, `rust/crates/runtime/src/mcp_client.rs`, `rust/crates/runtime/src/mcp_stdio.rs`, `rust/crates/runtime/src/config.rs` - prompt/context loading: `rust/crates/runtime/src/prompt.rs` - session compaction/runtime usage: `rust/crates/runtime/src/compact.rs`, `rust/crates/runtime/src/usage.rs` ### Missing or broken in Rust - **Missing many higher-level services**: analytics, plugin services, prompt suggestion, team memory sync, richer LSP service management, notifier/tips ecosystem, and much of the surrounding product/service scaffolding. - Rust is closer to a **runtime/API core** than a full parity implementation of the TS service layer. --- ## Highest-priority parity gaps after the critical bug fixes 1. **Hook execution parity** - Config exists, execution does not appear to. - This affects permissions, tool interception, and continuation behavior. 2. **Plugin system parity** - Entire install/load/manage surface appears missing. 3. **CLI breadth parity** - Missing many upstream command families and remote transports. 4. **Tool surface parity** - MVP tool registry exists, but a large number of upstream tool types are absent. 5. **Assistant orchestration parity** - Core loop exists, but advanced streaming/execution behaviors from TS are missing. ## Recommended next work after current critical fixes 1. Finish build/test/manual verification of the critical bug patch. 2. Implement **hook execution** before broadening the tool surface further. 3. Decide whether **plugins** are in-scope for parity; if yes, this likely needs dedicated design work, not a small patch. 4. Expand the CLI/tool matrix deliberately rather than adding one-off commands without shared orchestration support.