T3 Code 9-Provider Adapter Deep-Dive: JSON-RPC, ACP, Connect-RPC, SSE & SQLite (2026)

This document provides the wire-level engineering reference for all 9 provider drivers in pingdotgg/t3code (~/dev/t3code, commit 80455376f01f19c10a06dc08b0629486c017bf79). It documents the transport protocols, Orchestration v2 adapters (ClaudeAdapterV2.ts, CodexAdapterV2.ts, AntigravityAdapterV2.ts), session engines, permission mappers, Claude’s ENABLE_TOOL_SEARCH=auto 10x prompt-cache write mitigation, Antigravity’s Connect-RPC CSRF harvesting and IPv6 reachability diagnostics, Cursor’s SQLite hex-blob transcript DAG reader, OpenCode’s dual 1.x/2.x runtime support, and Muse’s parallel git worktree fan-out.

1. Provider Driver Matrix (packages/provider-* & apps/server/src/orchestration-v2/Adapters/)

Driver ID	Primary Packages & V2 Adapter Paths	Wire Transport & Framing	Native Rollback / Checkpoint
codex	packages/effect-codex-app-server, apps/server/src/provider/Drivers/CodexDriver.ts, apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts	JSON-RPC 2.0 bidirectional over stdio (codex app-server)	Yes (thread/rollback RPC with numTurns)
claude	apps/server/src/provider/Drivers/ClaudeDriver.ts, apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts	@anthropic-ai/claude-agent-sdk query() async generator + control stream	Yes (Query.rewindFiles(userMessageId))
acp-registry	packages/effect-acp, packages/provider-acp, packages/provider-acp-registry	@agentclientprotocol/sdk (ndJsonStream over stdio)	Via T3 Git checkpoints (refs/t3/checkpoints/)
antigravity	apps/server/src/provider/Drivers/AntigravityDriver.ts, apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.ts, AntigravityLanguageServer.ts, AntigravityAcpSupport.ts, AntigravityAuth.ts	Connect-RPC over local HTTP/2 TLS (127.0.0.1:<httpsPort>) + CSRF token	Trajectory step truncation
cursor	packages/provider-cursor (CursorAcpExtension.ts, CursorTranscriptReader.ts)	cursor-agent acp stdio + direct SQLite read (~/.cursor/chats/<hash>/<session>/store.db)	Via T3 Git checkpoints
grok	packages/provider-grok (GrokCliClient.ts, GrokXaiApiDriver.ts)	Dual engine: grok CLI subprocess OR direct https://api.x.ai/v1/responses SSE + 9 local tools	Via T3 Git checkpoints
opencode	packages/provider-opencode (OpenCodeClient.ts, OpenCode2Client.ts)	Gen 1 (opencode serve HTTP + SSE /event) OR Gen 2 (opencode app-server JSON-RPC)	Gen 1 /session/:id/revert / Gen 2
muse	packages/provider-muse (MuseDriver.ts, MuseWorktreePool.ts)	Multi-variant fan-out (1..4 parallel git worktree instances) wrapping claude/codex/opencode	Per-variant worktree branch reset
pi	packages/provider-pi (PiRpcClient.ts)	@mariozechner/pi-coding-agent (pi --mode rpc --no-session NDJSON stdio)	Via T3 Git checkpoints

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2. Codex Driver (packages/effect-codex-app-server & CodexAdapterV2.ts)

• Process Lifecycle & Protocol: Spawns codex app-server over stdio using JSON-RPC 2.0 (CodexAppServerClient.ts).
• Client-to-Server Requests: initialize, thread/start, thread/resume, thread/fork, thread/rollback ({ threadId, numTurns }), thread/compact/start, turn/start, turn/steer, turn/interrupt, review/start, command/exec, account/rateLimits/read.
• Server-to-Client Requests (Interactive Gates):
  • item/commandExecution/requestApproval → OrchestrationV2RuntimeRequest (kind: "command").
  • item/fileChange/requestApproval → OrchestrationV2RuntimeRequest (kind: "file-change").
  • item/tool/requestUserInput → OrchestrationV2RuntimeRequest (kind: "user_input").
  • item/tool/call → OrchestrationV2RuntimeRequest (kind: "dynamic_tool_call").
  • mcpServer/elicitation/request → OrchestrationV2RuntimeRequest (kind: "mcp-elicitation").

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3. Claude, ACP Registry & Antigravity Drivers

3.1 Claude Agent SDK (ClaudeAdapterV2.ts & ClaudeDriver.ts)

• SDK Execution: Invokes query({ prompt: promptInputQueue, options }) from @anthropic-ai/claude-agent-sdk.
• Critical ENABLE_TOOL_SEARCH=auto 10x Prompt-Cache Write Fix (ClaudeAdapterV2.ts:66-105, 1295-1356, commit 24c80f34):
  • Claude Code’s default ENABLE_TOOL_SEARCH=auto (or auto:N where 0 < N < 100) sends all MCP tool schemas inline whenever they fit under N% of a 1M context window, causing ~10x prompt-cache write billing per session.
  • claudeToolSearchOverride inspects .claude/settings.local.json (at both the main git checkout root and worktree cwd), .claude/settings.json, <claudeHome>/settings.json, and environment.ENABLE_TOOL_SEARCH. Whenever the effective setting is unset or auto / auto:N (0 < N < 100), T3 overrides effectiveQuerySettings.env.ENABLE_TOOL_SEARCH = "true" (preserving explicit false/0 or auto:0/auto:100).
• Background Task Settlement (t3_background_wait, commit 91ea0e18): Injects CLAUDE_BACKGROUND_WAIT_INSTRUCTIONS and marks OrchestrationV2PendingBackgroundTask.awaited = true so background tasks only hold turn settlement when explicitly awaited by the agent.
• Effort & Thinking Resolution (resolveEffort): Maps low / medium / high / xhigh / max / "ultrathink" (maxThinkingTokens) onto SDKOptions.effort and thinking.

3.2 ACP Registry (packages/provider-acp & packages/provider-acp-registry)

• Protocol Engine (AcpSessionEngine.ts): Uses @agentclientprotocol/sdk (ClientSideConnection, ndJsonStream, PROTOCOL_VERSION).
• 13 Curated Profiles (packages/provider-acp-registry/src/server/adapter.ts): claude-acp, github-copilot-cli (or local copilot binary), cursor, devin, factory-droid, gemini, goose, junie, kimi, kiro, mistral-vibe, opencode, qwen-code.
• Mistral Vibe Extension (adapter.ts:86-129): registerMistralVibeAcpExtensions handles _session/retrying notifications and rate-limit error code MISTRAL_VIBE_RATE_LIMITED = -31001.

3.3 Antigravity Language Server (AntigravityAdapterV2.ts, AntigravityLanguageServer.ts, AntigravityAcpSupport.ts, AntigravityAuth.ts)

• Connect-RPC over Local HTTP/2 TLS (AntigravityLanguageServer.ts): Spawns language_server_<platform> with --csrf_token <uuid> --random_port, discovers listening HTTPS/HTTP/extension ports via lsof / ss / netstat, and calls /exa.language_server_pb.LanguageServerService/{GetUserStatus, StartCascade, SendUserCascadeMessage, StreamCascadeReactiveUpdates, HandleCascadeUserInteraction, RevertToCascadeStep, CancelCascadeInvocation}.
• CSRF Header Harvesting: Intercepts the language server’s callback to the local --extension_server_port HTTP listener to capture any rotated x-codeium-csrf-token.
• RuntimeMode Mapping (AntigravityAcpSupport.ts:83-93): Maps "full-access" → "yolo", "auto-accept-edits" → "auto_edit", and both "auto" and "approval-required" → "default".
• IPv6 Google OAuth Reachability Diagnostic (AntigravityAuth.ts:36-41, commit 28878555): Emits NO_RESPONSE_HINT_MS = 30_000 ("Antigravity has not reached Google after 30 seconds. Check this machine's network connection. Broken IPv6 is a common cause.") when bundled Python lacks Happy Eyeballs IPv4 fallback.

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4. Cursor, Grok, OpenCode, Muse & Pi Drivers

4.1 Cursor Driver (packages/provider-cursor)

• ACP Extension (CursorAcpExtension.ts): Handles cursor/ask_question, cursor/create_plan, cursor/update_todos, and cursor/task.
• SQLite Hex-Blob Transcript Reader (CursorTranscriptReader.ts): Opens ~/.cursor/chats/md5(workspacePath)/<sessionId>/store.db (meta table hex-encoded JSON + blobs table protobuf/JSON DAG nodes) to recover full message and tool history when resuming native Cursor sessions.

4.2 Grok Driver (packages/provider-grok)

• Dual Engine: GrokCliClient.ts wraps the @vibe-kit/grok-cli subprocess; GrokXaiApiDriver.ts speaks directly to https://api.x.ai/v1/responses (SSE) and executes 9 local workspace tools (bash, read_file, write_file, edit_file, list_directory, glob, grep, web_search, x_search).

4.3 OpenCode 1.x & 2.x (packages/provider-opencode)

• OpenCode 1.x (OpenCodeClient.ts): Spawns opencode serve --hostname 127.0.0.1 --port <port>, consuming GET /event SSE (message.part.updated, permission.asked, question.asked) and dispatching POST /session/:id/prompt_async.
• OpenCode 2.x (OpenCode2Client.ts): Connects to opencode app-server over JSON-RPC (session.create, turn.start, turn.steer, request.respond).

4.4 Muse Multi-Variant Worktree Orchestrator (packages/provider-muse) & Pi Driver (packages/provider-pi)

• Muse (MuseDriver.ts, MuseWorktreePool.ts): Provisions variantCount (1..4) isolated git worktrees under <worktreesDir>/muse/<threadId>/variant-<i+1>, dispatches the prompt in parallel across inner providers (claude, codex, opencode), and exposes an adopt_variant tool to cherry-pick or reset the parent workspace to the winning variant’s branch.
• Pi (PiRpcClient.ts): Spawns pi --mode rpc --no-session (@mariozechner/pi-coding-agent) over NDJSON stdio (prompt, steer, abort, set_model, set_thinking_level, extension_ui_response).