diff --git a/examples/acp-agent/README.md b/examples/acp-agent/README.md
index 58ba92cd0e..2ca4de690b 100644
--- a/examples/acp-agent/README.md
+++ b/examples/acp-agent/README.md
@@ -6,7 +6,7 @@ The DeepSeek Harness coding agent exposed as an **Agent Client Protocol (ACP)**
 pnpm run demo:acp          # needs DEEPSEEK_API_KEY (repo-root .env or env)
 ```
 
-This example is just a leaf `cordis.yml`: it loads the [`@deepseek-ai/dsh-acp-agent`](../../packages/ui/acp-agent) app (which bundles the [`@deepseek-ai/dsh-agent-core`](../../packages/core/agent-core) spine, JSONL session persistence, and the `@deepseek-ai/dsh-acp` bridge — with **no pre-created agents**, since ACP `session/new` creates them on demand), the swappable DeepSeek and bash backends, and the optional model-facing `subagent`/`subagent_fork`/`todo_write` tool entries. The app package bakes in the no-stdout-logger cluster, so a leaf has no logger entry to get wrong by default — keeping stdout pure for JSON-RPC.
+This example is just a leaf `cordis.yml`: it loads the [`@deepseek-ai/dsh-acp-agent`](../../packages/ui/acp-agent) app (which bundles the [`@deepseek-ai/dsh-agent-core`](../../packages/core/agent-core) spine, JSONL session persistence, and the `@deepseek-ai/dsh-acp` bridge — with **no pre-created agents**, since ACP `session/new` creates them on demand), the swappable DeepSeek, bash, and filesystem backends, and the model-facing `read`/`write`/`edit`/`subagent`/`subagent_fork`/`todo_write` tool entries. The app package bakes in the no-stdout-logger cluster, so a leaf has no logger entry to get wrong by default — keeping stdout pure for JSON-RPC.
 
 ## stdout is the protocol
 
@@ -28,7 +28,7 @@ Add to your Zed `settings.json` under `agent_servers`:
 }
 ```
 
-The editor sets each session's `cwd` to the project it opens; the agent's bash tools run there (see the per-session `cwd` note in `packages/ui/acp`), so launch the server from the harness repo with `pnpm --dir …` and let ACP carry the workspace path per session.
+The editor sets each session's `cwd` to the project it opens; the agent's bash tools run there (see the per-session `cwd` note in `packages/ui/acp`). The filesystem tools in this demo use the local filesystem backend and resolve relative paths from the server launch directory, so launch the server from the harness repo with `pnpm --dir …` when using `read`/`write`/`edit` against this checkout.
 
 ## Snapshot tests (record-once / replay-deterministic)
 
diff --git a/examples/acp-agent/cordis.snapshot.yml b/examples/acp-agent/cordis.snapshot.yml
index f03cc49223..8a6f17d012 100644
--- a/examples/acp-agent/cordis.snapshot.yml
+++ b/examples/acp-agent/cordis.snapshot.yml
@@ -18,7 +18,7 @@
 
 # Local bash executor for agent-core's tool-bash schema.
 # FIXME(config-comments): keep this executor note from implying bash is the
-# whole tool set; subagent and todo_write are loaded below.
+# whole tool set; filesystem, subagent, and todo_write are loaded below.
 - id: bash
   name: '@deepseek-ai/dsh-bash-local'
   config:
@@ -33,12 +33,13 @@
     systemPrompt: |
       You are a coding assistant driven over the Agent Client Protocol.
 
-      Your tools are bash (plus bash_output/bash_kill for background tasks)
-      and subagent. Do ALL file operations through bash: read with
-      cat/sed/head, search with grep, write with heredocs (cat <<'EOF' >
-      file), edit with sed or a rewrite. Each bash call runs in a fresh
-      shell — pass workdir instead of cd. Check the [exit code: N] marker;
-      verify your work. Keep answers brief and factual.
+      Your tools are read/write/edit for file operations, bash (plus
+      bash_output/bash_kill for background tasks), and subagent. Use read to
+      inspect UTF-8 text files, write to create or replace files, and edit for
+      targeted literal replacements. Use bash for shell commands, tests,
+      searches, and operations that are not ordinary file reads or edits. Each
+      bash call runs in a fresh shell — pass workdir instead of cd. Check the
+      [exit code: N] marker; verify your work. Keep answers brief and factual.
 
       Use the subagent tool to delegate a focused, self-contained subtask to
       a fresh child agent (it works in its own context and returns only its
@@ -85,3 +86,16 @@
 # replayed todo_write tool call resolves to a real tool during snapshot replay.
 - id: tool-todo
   name: '@deepseek-ai/dsh-tool-todo'
+
+# Filesystem capability stack — identical to cordis.yml's wiring, so replayed
+# read/write/edit tool calls resolve to the real tools during snapshot replay.
+- id: fs-local
+  name: '@deepseek-ai/dsh-fs-local'
+  config:
+    cwd: !!js process.cwd()
+
+- id: fs-policy
+  name: '@deepseek-ai/dsh-fs-policy'
+
+- id: tool-fs
+  name: '@deepseek-ai/dsh-tool-fs'
diff --git a/examples/acp-agent/cordis.yml b/examples/acp-agent/cordis.yml
index 31d4d5429a..35c3176f34 100644
--- a/examples/acp-agent/cordis.yml
+++ b/examples/acp-agent/cordis.yml
@@ -1,8 +1,9 @@
 # The acp-agent plugin tree: the ACP server. Also the snapshot RECORD config
 # (the dsh-acp-agent bin selects it for DSH_SNAPSHOT=record): a real llm-deepseek
 # run whose persisted log the snapshot harness harvests. The swappable DeepSeek
-# adapter and local bash executor, the ACP server app (@deepseek-ai/dsh-acp-agent),
-# and the optional model-facing subagent/todo tools loaded below.
+# adapter, local bash/filesystem executors, the ACP server app
+# (@deepseek-ai/dsh-acp-agent), and the optional model-facing fs/subagent/todo
+# tools loaded below.
 #
 # CRITICAL: this tree loads NO stdout logger and NO hmr — stdout is reserved for
 # the ACP JSON-RPC protocol (see packages/ui/acp). That guarantee is now a
@@ -24,7 +25,7 @@
 
 # Local bash executor for agent-core's tool-bash schema.
 # FIXME(config-comments): keep this executor note from implying bash is the
-# whole tool set; subagent and todo_write are loaded below.
+# whole tool set; filesystem, subagent, and todo_write are loaded below.
 - id: bash
   name: '@deepseek-ai/dsh-bash-local'
   config:
@@ -41,12 +42,13 @@
     systemPrompt: |
       You are a coding assistant driven over the Agent Client Protocol.
 
-      Your tools are bash (plus bash_output/bash_kill for background tasks)
-      and subagent. Do ALL file operations through bash: read with
-      cat/sed/head, search with grep, write with heredocs (cat <<'EOF' >
-      file), edit with sed or a rewrite. Each bash call runs in a fresh
-      shell — pass workdir instead of cd. Check the [exit code: N] marker;
-      verify your work. Keep answers brief and factual.
+      Your tools are read/write/edit for file operations, bash (plus
+      bash_output/bash_kill for background tasks), and subagent. Use read to
+      inspect UTF-8 text files, write to create or replace files, and edit for
+      targeted literal replacements. Use bash for shell commands, tests,
+      searches, and operations that are not ordinary file reads or edits. Each
+      bash call runs in a fresh shell — pass workdir instead of cd. Check the
+      [exit code: N] marker; verify your work. Keep answers brief and factual.
 
       Use the subagent tool to delegate a focused, self-contained subtask to
       a fresh child agent (it works in its own context and returns only its
@@ -95,3 +97,18 @@
 # session log (todo/write), surfaced to the ACP client as a `plan` update.
 - id: tool-todo
   name: '@deepseek-ai/dsh-tool-todo'
+
+# Filesystem capability stack: local provider, read-before-write/edit policy
+# gate, then the model-facing read/write/edit tools. Relative filesystem paths
+# resolve from the server launch cwd; the documented Zed setup launches this
+# demo from the harness checkout with `pnpm --dir`.
+- id: fs-local
+  name: '@deepseek-ai/dsh-fs-local'
+  config:
+    cwd: !!js process.cwd()
+
+- id: fs-policy
+  name: '@deepseek-ai/dsh-fs-policy'
+
+- id: tool-fs
+  name: '@deepseek-ai/dsh-tool-fs'