diff --git a/docs/acp-feature-support.md b/docs/acp-feature-support.md
new file mode 100644
index 0000000000..a0e1dd26cd
--- /dev/null
+++ b/docs/acp-feature-support.md
@@ -0,0 +1,163 @@
+# ACP feature support checklist
+
+A structured inventory of [Agent Client Protocol](https://agentclientprotocol.com) (ACP) features and where the harness's ACP bridge ([`@deepseek-ai/dsh-acp`](../packages/acp/README.md)) stands on each. The bridge exposes the harness agent as an ACP **server** (the agent side of an editor↔agent connection), so "supported" below means *the bridge implements the agent's half* — answering an agent method, advertising a capability, or calling a client method.
+
+## Scope
+
+This tracks the **stable** ACP v1 surface (schema `1.14.0`, `schema/v1/schema.json`) PLUS the **unstable/draft** features that the two reference adapters — [`claude-agent-acp`](https://github.com/zed-industries/claude-code-acp) (Claude Code) and [`codex-acp`](https://github.com/zed-industries/codex-acp) (OpenAI Codex) — actually ship. A purely-unstable feature that neither reference adapter uses is omitted (see [Out of scope](#out-of-scope)).
+
+Legend: ✅ supported · ⚠️ partial / fallback · ❌ not yet · — n/a. The **Stable** column marks whether the feature is in the released v1 schema (S) or only the unstable schema (U). The **Claude** / **Codex** columns record whether each reference adapter ships it, as a maturity signal.
+
+## At a glance
+
+The bridge implements the **core prompt-turn loop** for N concurrent sessions: initialize, session new/load, prompt, cancel, streamed assistant/thought chunks, tool-call rendering (including Zed terminal cards), and resumable session replay. The largest **unbuilt** areas are the **permission gate** (`session/request_permission`), the client **filesystem** and **terminal** method families, **MCP passthrough**, **session modes / config options / model selection**, **slash commands**, and **agent plans** — all of which both reference adapters ship. See [Gap summary](#gap-summary).
+
+## 1. Agent methods (client → agent)
+
+| Method | Stable | Bridge | Claude | Codex | Notes |
+|---|---|---|---|---|---|
+| `initialize` | S | ✅ | ✅ | ✅ | Negotiates `PROTOCOL_VERSION`; advertises `loadSession` + baseline prompt caps. Snapshots the Zed `_meta.terminal_output` client cap. |
+| `authenticate` | S | ⚠️ | ✅ | ✅ | No-op stub; the bridge advertises no `authMethods`, so there is nothing to authenticate. |
+| `logout` | S | ❌ | ✅ | ✅ | Gated by `agentCapabilities.auth.logout`; not advertised. |
+| `session/new` | S | ✅ | ✅ | ✅ | Maps to `agents.create`; requires an absolute `cwd` (becomes the session workspace); rejects non-empty `additionalDirectories` / `mcpServers`. |
+| `session/load` | S | ✅ | ✅ | ✅ | Maps to `agents.resume` + full event-log replay; validates persisted `cwd` before constructing the agent. |
+| `session/resume` | S | ❌ | ✅ | ✅ | Reconnect WITHOUT replay; gated by `sessionCapabilities.resume`. Not advertised. |
+| `session/close` | S | ⚠️ | ✅ | ✅ | No explicit `session/close` handler; the bridge tears a session down on client disconnect / disposal, not on demand per session. |
+| `session/prompt` | S | ✅ | ✅ | ✅ | Maps to `agent.send`; one in-flight prompt per session; settles on the owning turn's end. |
+| `session/cancel` | S | ✅ | ✅ | ✅ | Queue-aware `agent.cancel`; settles the in-flight prompt `cancelled`, scoped to the one session. |
+| `session/set_mode` | S | ❌ | ✅ | ✅ | Session modes not modeled (see [§6 Modes](#6-session-modes--config-options--models)). |
+| `session/set_config_option` | S | ❌ | ✅ | ✅ | Config options not modeled. |
+| model selection | S | ❌ | ✅ | ✅ | No distinct stable `session/set_model` — model is the `model`-category `session/set_config_option`. The bridge fixes the model per-bridge via config; no runtime switch. Codex still uses the legacy `unstable_setSessionModel` ext method. |
+| `session/list` | S | ❌ | ✅ | ✅ | Gated by `sessionCapabilities.list`. The harness HAS `sessionPersistence.list()` (used internally for load-cwd validation) but does not expose it over ACP. |
+| `session/delete` | S | ❌ | ✅ | ✅ | Gated by `sessionCapabilities.delete`. |
+| `session/fork` | U | ❌ | ✅ | ❌ | Claude ships `unstable_forkSession`; Codex does not. |
+
+## 2. Client methods the agent CALLS (agent → client)
+
+These are capabilities the bridge would *drive* on the editor. The harness runs tools in-process (its own `dsh-bash` executor, direct file I/O), so it does not yet delegate to the editor for any of these.
+
+| Method | Stable | Bridge | Claude | Codex | Notes |
+|---|---|---|---|---|---|
+| `session/update` | S | ✅ | ✅ | ✅ | The bridge's primary output channel (see [§4](#4-sessionupdate-variants)). |
+| `session/request_permission` | S | ❌ | ✅ | ✅ | **The biggest gap.** Tools run with the executor's full authority; no user authorization round-trip. The `agent→sessionId` reverse map is already in place to route a future permission request. Tracked `TODO(rfc010-permission-gate)`. |
+| `fs/read_text_file` | S | ❌ | ✅ | ❌ | The harness reads files directly (it does not see the editor's unsaved buffer state). Claude delegates; Codex does not. |
+| `fs/write_text_file` | S | ❌ | ✅ | ❌ | Same — direct writes, no editor delegation. |
+| `terminal/create` | S | ❌ | ❌ | ❌ | Neither reference adapter drives the client terminal API either — both, like the bridge, render shell output as tool-call content + a `_meta` channel (see [§5 Terminal](#terminal-rendering)). |
+| `terminal/output` | S | ❌ | ❌ | ❌ | As above. |
+| `terminal/wait_for_exit` | S | ❌ | ❌ | ❌ | As above. |
+| `terminal/kill` | S | ❌ | ❌ | ❌ | As above. |
+| `terminal/release` | S | ❌ | ❌ | ❌ | As above. |
+| `elicitation/create` · `elicitation/complete` | U | ❌ | ✅ | ✅ | Structured user-input forms; both adapters use the `unstable_*` elicitation methods (mostly to surface MCP server elicitations). |
+
+## 3. Capabilities
+
+### 3a. `agentCapabilities` (advertised by the bridge)
+
+| Capability | Stable | Bridge | Claude | Codex | Notes |
+|---|---|---|---|---|---|
+| `loadSession` | S | ✅ | ✅ | ✅ | Advertised `true`; backs `session/load`. |
+| `promptCapabilities.image` | S | ❌ | ✅ | ✅ | Bridge advertises `image: false`; image prompt blocks are rejected. |
+| `promptCapabilities.audio` | S | ❌ | ❌ | ❌ | `audio: false`; neither adapter accepts audio either. |
+| `promptCapabilities.embeddedContext` | S | ❌ | ✅ | ✅ | `embeddedContext: false`; embedded `resource` blocks rejected. |
+| `mcpCapabilities.{http,sse}` | S | ❌ | ✅ | ⚠️ | No MCP passthrough; `mcpServers` is rejected. Claude advertises http+sse, Codex http only. |
+| `sessionCapabilities.*` | S | ❌ | ✅ | ✅ | None advertised (list/delete/resume/close/additionalDirectories/fork all off). |
+| `auth.logout` | S | ❌ | ✅ | ✅ | Not advertised. |
+| `authMethods[]` | S | ⚠️ | ✅ | ✅ | Advertised as empty (no auth required to reach the model). |
+| `agentInfo` (name/version) | S | ✅ | ✅ | ✅ | From `agentName` / `agentVersion` config. |
+| `_meta` custom caps | S | ❌ | ✅ | — | E.g. Claude's `claudeCode.promptQueueing`. The bridge advertises no custom `_meta`. |
+
+### 3b. `clientCapabilities` (consumed by the bridge)
+
+| Capability | Stable | Bridge | Notes |
+|---|---|---|---|
+| `fs.{readTextFile,writeTextFile}` | S | ❌ | Not consulted (the bridge never calls `fs/*`). |
+| `terminal` | S | ❌ | Not consulted; the bridge keys terminal rendering off the Zed `_meta.terminal_output` cap instead. |
+| `_meta.terminal_output` (Zed) | S (`_meta`) | ✅ | Snapshotted per session at create/load; gates terminal-card rendering. |
+
+## 4. `session/update` variants
+
+| `sessionUpdate` | Stable | Bridge | Claude | Codex | Notes |
+|---|---|---|---|---|---|
+| `agent_message_chunk` | S | ✅ | ✅ | ✅ | From `assistant/chunk` text-delta. |
+| `agent_thought_chunk` | S | ✅ | ✅ | ✅ | From `assistant/chunk` reasoning-delta. |
+| `user_message_chunk` | S | ✅ | ✅ | ✅ | Emitted during `session/load` replay to reconstruct the user side. |
+| `tool_call` | S | ✅ | ✅ | ✅ | Tool-owned presentation (`presentCall`); see [§5](#5-tool-call-rendering). |
+| `tool_call_update` | S | ✅ | ✅ | ✅ | From `tool/result` via `presentResult`. |
+| `plan` | S | ❌ | ✅ | ⚠️ | No agent plan emitted. Claude emits real plan entries; Codex renders plan as plain message text. |
+| `available_commands_update` | S | ❌ | ✅ | ✅ | No slash commands advertised. |
+| `current_mode_update` | S | ❌ | ✅ | ✅ | No session modes. |
+| `config_option_update` | S | ❌ | ✅ | ✅ | No config options. |
+| `usage_update` | S | ❌ | ✅ | ✅ | Token/cost reporting not surfaced (the harness HAS usage events internally). |
+| `session_info_update` | S | ❌ | ⚠️ | ⚠️ | Session title/metadata not pushed. |
+
+## 5. Tool-call rendering
+
+Tool-call presentation is **owned by each tool** (`presentCall` / `presentResult` on the `dsh-tools` definition), not special-cased in the bridge — see the [terminal-and-tool-rendering RFC](rfc/implemented/2026-06-18-acp-terminal-and-tool-rendering.md).
+
+| Feature | Stable | Bridge | Claude | Codex | Notes |
+|---|---|---|---|---|---|
+| `ToolCallKind` mapping | S | ✅ | ✅ | ✅ | `execute`/`read`/`edit`/`other` inferred from the tool; richer mapping possible. |
+| `ToolCallStatus` | S | ✅ | ✅ | ✅ | `in_progress` → `completed`/`failed`. |
+| `content` blocks | S | ✅ | ✅ | ✅ | Text content; the description renders above the card. |
+| `diff` content | S | ❌ | ✅ | ✅ | No structured diff rendering for edits (would need a diffing edit tool + presenter). |
+| `terminal` content | S | ✅ | ✅ | ✅ | Via the Zed `_meta` terminal convention (see below), not the spec `terminal/*` sub-protocol. |
+| `locations` (follow-along) | S | ❌ | ✅ | ✅ | No file-location hints emitted. |
+| `rawInput` | S | ✅ | ⚠️ | ✅ | Parsed tool args surfaced as `rawInput`. |
+| `rawOutput` | S | ❌ | ⚠️ | ✅ | Not emitted. |
+
+### Terminal rendering
+
+⚠️ Implemented via the **Zed `_meta` convention** (`terminal_info` / `terminal_output` / `terminal_exit`), gated on the client advertising `_meta.terminal_output` — NOT the spec's `terminal/create` sub-protocol (which would make the editor execute the command, bypassing `dsh-bash`'s sandbox / env-scrub / ownership / cwd). Both reference adapters take the same `_meta` approach. Live incremental streaming (`terminal_output_delta`, which Codex negotiates) is a follow-up — the bridge currently sends the full captured output once on the result.
+
+## 6. Session modes / config options / models
+
+❌ None modeled. Both reference adapters ship modes (Claude: a "plan" auto-mode; Codex: read-only / agent / agent-full-access mapping to its approval+sandbox policy), the newer config-option surface, and runtime model selection. The harness fixes the model per-bridge via `AcpConfig.model`. These are coupled to the unbuilt **permission gate** (a mode often selects an approval policy), so they are natural follow-ups to it.
+
+## 7. Content blocks
+
+| Block | Stable | In prompts | In updates | Notes |
+|---|---|---|---|---|
+| `text` | S | ✅ | ✅ | Baseline. |
+| `resource_link` | S | ✅ | ⚠️ | Accepted in prompts and rendered into text (`acpPromptToText`); not emitted as a structured update block. |
+| `image` | S | ❌ | ❌ | Rejected in prompts (`promptCapabilities.image: false`). |
+| `audio` | S | ❌ | ❌ | Rejected. |
+| `resource` (embedded) | S | ❌ | ❌ | Rejected (`embeddedContext: false`). |
+
+The bridge rejects unsupported prompt blocks rather than silently dropping them (`promptHasUnsupportedContent`), per the "explicit over implicit" convention.
+
+## 8. Cross-cutting
+
+| Feature | Stable | Bridge | Notes |
+|---|---|---|---|
+| `StopReason` mapping | S | ✅ | `turnEndToStopReason` is total over harness turn-end reasons → `end_turn`/`max_tokens`/`cancelled`. |
+| Multi-session (N per connection) | S | ✅ | Strict per-session demux; concurrent streams never interleave. See the [multi-session RFC](rfc/proposed/2026-06-14-acp-multi-session.md). |
+| Disconnect / disposal teardown | S | ✅ | Quiesces every live session on client disconnect or Cordis disposal. |
+| `_meta` extensibility | S | ⚠️ | Consumed (Zed terminal cap) and emitted (terminal `_meta`); no other custom extensions. |
+| Background-task ownership isolation | — | ✅ | `bash_output`/`bash_kill` reject another session's task via an opaque owner token. |
+| stdout-is-the-protocol guarantee | S | ✅ | The bridge runs in an example with no stdout logger. |
+
+## Gap summary
+
+Ranked by how commonly the reference adapters ship them and how much UX they unlock:
+
+1. **Permission gate** — `session/request_permission` + permission options. Tracked `TODO(rfc010-permission-gate)`; the reverse map is already wired. Foundational, and a prerequisite for modes.
+2. **Session lifecycle** — `session/list` + `session/delete` (the persistence layer already lists), then `session/resume` / `session/close`.
+3. **Modes / config options / model selection** — coupled to the permission gate.
+4. **Agent plan** (`sessionUpdate: 'plan'`) — surface the loop's plan as structured entries.
+5. **Slash commands** (`available_commands_update`).
+6. **MCP passthrough** (`mcpServers` on `session/new` + `mcpCapabilities`).
+7. **Richer prompt content** — image / embedded `resource` blocks (needs a multimodal model path).
+8. **Diff + location tool rendering** — `diff` content and `locations` for edit tools.
+9. **Usage reporting** (`usage_update`) — the harness already has the internal usage events.
+10. **Editor filesystem delegation** (`fs/read_text_file` / `fs/write_text_file`) — lets the agent see unsaved buffers; lower priority since the harness has direct disk access.
+
+## Out of scope
+
+Unstable/draft ACP features that **neither** reference adapter ships are not tracked above: `providers/*` (LLM provider selection), `mcp/connect`·`mcp/message`·`mcp/disconnect` (client-side MCP passthrough), `nes/*` (Next Edit Suggestion), `document/did*` (LSP-style document sync), the v2 plan model (`plan_update` / `plan_removed`), boolean config options, `$/cancel_request`, and the draft Streamable-HTTP transport. They can be added if a target editor adopts them.
+
+## Sources
+
+- Stable spec: `schema/v1/schema.json` (schema `1.14.0`) and `docs/protocol/v1/*.mdx` in the [agent-client-protocol](https://github.com/agentclientprotocol/agent-client-protocol) repo.
+- Reference adapters: [`claude-agent-acp`](https://github.com/zed-industries/claude-code-acp) and [`codex-acp`](https://github.com/zed-industries/codex-acp).
+- Bridge: [`packages/acp/README.md`](../packages/acp/README.md), [`packages/acp/src/index.ts`](../packages/acp/src/index.ts), and the ACP RFCs under [`docs/rfc/`](rfc/README.md).
+</content>