docs: rename the agent kit block to sandbox

Rename the spec.yaml agent: block to sandbox: and its field paths
(agent.image, agent.aiFilename, agent.entrypoint) to sandbox.*. Update
the "Agent block" reference heading and its #agent-block anchor to
"Sandbox block"/#sandbox-block, repoint cross-links, and rename the
tutorial's "Write the agent block" section.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dvdksn

content/manuals/ai/sandboxes/customize/_index.md

@@ -45,7 +45,7 @@ agent runs in. Use kits for things that vary per agent or per team:
 shared linter config, project-specific install steps, credential
 injection for a service the agent talks to.
 
-Templates and kits work together. A sandbox kit's `agent.image` field
+Templates and kits work together. A sandbox kit's `sandbox.image` field
 points at a template: the template provides the base environment, the
 kit layers config, secrets, and runtime behavior on top. A team can ship
 one heavy template and several thin kits without rebuilding the image

content/manuals/ai/sandboxes/customize/build-an-agent.md

@@ -65,9 +65,9 @@ substitutes the real key on outbound requests to the API host, so the
 secret never enters the sandbox. A later section walks through the
 specific command for storing the key.
 
-## Write the agent block
+## Write the sandbox block
 
-The `agent:` block tells the sandbox how to launch Amp when the user
+The `sandbox:` block tells the sandbox how to launch Amp when the user
 attaches.
 
 ```yaml {title="amp/spec.yaml"}
@@ -77,7 +77,7 @@ name: amp
 displayName: Amp
 description: The frontier coding agent.
 
-agent:
+sandbox:
   image: "docker/sandbox-templates:shell-docker"
   aiFilename: AGENTS.md
   entrypoint:
@@ -181,7 +181,7 @@ name: amp
 displayName: Amp
 description: The frontier coding agent.
 
-agent:
+sandbox:
   image: "docker/sandbox-templates:shell-docker"
   aiFilename: AGENTS.md
   entrypoint:

content/manuals/ai/sandboxes/customize/kit-examples.md

@@ -266,7 +266,7 @@ name: claude-safe
 displayName: Claude Code (with approval prompts)
 description: Claude Code without --dangerously-skip-permissions
 
-agent:
+sandbox:
   image: "docker/sandbox-templates:claude-code-docker"
   aiFilename: CLAUDE.md
   entrypoint:

content/manuals/ai/sandboxes/customize/kit-reference.md

@@ -1,7 +1,7 @@
 ---
 title: Kit spec reference
 linkTitle: Spec reference
-description: Field-by-field reference for a kit's spec.yaml — credentials, network rules, environment, commands, files, agent context, and the agent block.
+description: Field-by-field reference for a kit's spec.yaml — credentials, network rules, environment, commands, files, agent context, and the sandbox block.
 keywords: sandboxes, sbx, kits, spec.yaml, reference, schema, fields
 weight: 22
 ---
@@ -45,8 +45,8 @@ description: <text>
 | `displayName`   | No       | Human-readable name.                                                       |
 | `description`   | No       | Short description.                                                         |
 
-The sections below apply to both kinds. Sandbox kits also declare an
-[`agent:` block](#agent-block).
+The sections below apply to both kinds. Sandbox kits also declare a
+[`sandbox:` block](#sandbox-block).
 
 ## Credentials
 
@@ -275,7 +275,7 @@ Top-level field. Available in both mixin and sandbox kits. Markdown
 appended to the agent's memory file at sandbox creation. The agent reads
 this content at startup. Write it as instructions or notes the agent
 should follow when working in the sandbox. Applied only when the active
-sandbox kit sets [`agent.aiFilename`](#agent-block).
+sandbox kit sets [`sandbox.aiFilename`](#sandbox-block).
 
 The file is written to the parent of the workspace path inside the
 sandbox, not to the workspace itself. For a workspace mounted at
@@ -293,25 +293,25 @@ across files instead of being concatenated into the main one:
   `<!-- sbx:kits-section start -->` and `<!-- sbx:kits-section end -->`
   markers so it can be regenerated when kits are added or removed.
 
-## Agent block
+## Sandbox block
 
 Required for `kind: sandbox`.
 
 ```yaml
-agent:
+sandbox:
   image: <image-ref>
   aiFilename: <filename>
   entrypoint:
     run: [<argv>, ...]
     args: [<arg>, ...]
 ```
 
-| Field                   | Required | Description                                                                                                 |
-| ----------------------- | -------- | ----------------------------------------------------------------------------------------------------------- |
-| `agent.image`           | Yes      | Docker image reference. See [Base image requirements](#base-image-requirements).                            |
-| `agent.aiFilename`      | No       | Memory filename (for example, `AGENTS.md`). Appends top-level [`agentContext`](#agent-context) at creation. |
-| `agent.entrypoint.run`  | No       | Command and args as a string array. Replaces the image's entrypoint.                                        |
-| `agent.entrypoint.args` | No       | Args appended to the image's existing entrypoint.                                                           |
+| Field                     | Required | Description                                                                                                 |
+| ------------------------- | -------- | ----------------------------------------------------------------------------------------------------------- |
+| `sandbox.image`           | Yes      | Docker image reference. See [Base image requirements](#base-image-requirements).                            |
+| `sandbox.aiFilename`      | No       | Memory filename (for example, `AGENTS.md`). Appends top-level [`agentContext`](#agent-context) at creation. |
+| `sandbox.entrypoint.run`  | No       | Command and args as a string array. Replaces the image's entrypoint.                                        |
+| `sandbox.entrypoint.args` | No       | Args appended to the image's existing entrypoint.                                                           |
 
 ### Base image requirements
 

content/manuals/ai/sandboxes/customize/kits.md

@@ -209,7 +209,7 @@ agentContext: |
 ```
 
 Both mixin and sandbox kits can declare `agentContext:`. The content is written
-only when the active sandbox kit sets [`agent.aiFilename`](kit-reference.md#agent-block),
+only when the active sandbox kit sets [`sandbox.aiFilename`](kit-reference.md#sandbox-block),
 which determines the memory file's name.
 
 When more than one loaded kit declares an `agentContext:` block, each kit's
@@ -231,11 +231,11 @@ See [`agentContext`](kit-reference.md#agent-context) in the spec reference for t
 
 ### Define an agent
 
-Sandbox kits declare an `agent:` block with the image the agent runs in and
+Sandbox kits declare a `sandbox:` block with the image the agent runs in and
 the command the user attaches to when they launch the sandbox:
 
 ```yaml
-agent:
+sandbox:
   image: "my-registry/my-agent:latest"
   entrypoint:
     run: [my-agent, "--yolo"]
@@ -318,21 +318,21 @@ everything the agent needs. Common use cases:
 - Prototype a new agent integration
 
 Sandbox kits declare everything a mixin kit can, plus an
-[`agent:` block](kit-reference.md#agent-block) that tells the sandbox how to launch the
+[`sandbox:` block](kit-reference.md#sandbox-block) that tells the sandbox how to launch the
 agent. For a step-by-step walkthrough, see
 [Build your own agent kit](build-an-agent.md).
 
 ### Example: the built-in `claude` agent
 
 The `claude` agent you get from `sbx run claude` is defined as a kit. Here
-is an abbreviated version of its spec, showing how the agent block combines
+is an abbreviated version of its spec, showing how the sandbox block combines
 with network, credentials, environment, and commands:
 
 ```yaml {title="claude/spec.yaml"}
 schemaVersion: "1"
 kind: sandbox
 name: claude
-agent:
+sandbox:
   image: "docker/sandbox-templates:claude-code-docker"
   aiFilename: CLAUDE.md
   entrypoint:
@@ -460,7 +460,7 @@ Docker credential store, so pushing to a private registry requires a prior
 
 For a field-by-field reference of every `spec.yaml` block — top-level
 fields, credentials, network, environment, commands, static files,
-agent context, and the agent block — see [Kit spec reference](kit-reference.md).
+agent context, and the sandbox block — see [Kit spec reference](kit-reference.md).
 
 ## Debugging
 

content/manuals/ai/sandboxes/faq.md

@@ -119,7 +119,7 @@ without `--dangerously-skip-permissions`:
 schemaVersion: "1"
 kind: sandbox
 name: claude-safe
-agent:
+sandbox:
   image: "docker/sandbox-templates:claude-code-docker"
   entrypoint:
     run: [claude]