claw-code/PARITY.md

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.