chore: release v4.5.0-rc.7 (#3932)

## Summary
7 improvements.

## Improvements
- `@trigger.dev/sdk` now bundles the Trigger.dev agent skills and a
curated snapshot of the docs those skills reference. The skills that
`trigger skills` installs into your coding agent read this content from
node_modules, so the guidance your AI assistant follows is pinned to the
SDK version installed in your project and stays current across upgrades
instead of going stale until the next reinstall.
([#3937](#3937))
- Running a CLI command like `dev`, `deploy`, `preview`, or `update`
before initializing a project no longer crashes with a raw `Cannot find
matching package.json` stack trace. The CLI now detects the missing
project and points you to `npx trigger.dev@latest init` instead.
([#3929](#3929))
- The agent skills installed by `trigger skills` are now namespaced with
a `trigger-` prefix (e.g. `trigger-authoring-tasks`,
`trigger-getting-started`) so they don't collide with unrelated skills
in your coding agent's skills directory. Adds a `trigger-cost-savings`
skill for auditing and reducing compute spend (right-sizing machines,
`maxDuration`, batching, debounce), and `@trigger.dev/sdk` now bundles
the full Trigger.dev documentation so your agent can read the complete,
version-pinned reference directly from node_modules.
([#3970](#3970))
- The run span API response now includes `cachedCost` and
`cacheCreationCost` on the `ai` object, alongside the existing
`inputCost` / `outputCost` / `totalCost`. `inputCost` reflects only the
non-cached input, so these fields let you reconstruct the full cost
breakdown for prompt-cached calls.
([#3958](#3958))
- `chat.headStart` now works with the `chat.customAgent` and
`chat.createSession` backends, not only `chat.agent`. The warm step-1
response hands over to your loop the same way it does for a managed
agent. ([#3963](#3963))
  
  In a `chat.customAgent` loop, consume the handover on turn 0:
  
  ```ts
  const conversation = new chat.MessageAccumulator();
const { isFinal, skipped } = await conversation.consumeHandover({
payload });
  if (skipped) return; // warm handler aborted, so exit without a turn
  if (isFinal) {
await chat.writeTurnComplete(); // step 1 is the response, no streamText
  } else {
const result = streamText({ model, messages: conversation.modelMessages,
tools });
// Pass originalMessages so the handed-over tool round merges into the
    // step-1 assistant instead of starting a new message.
    const response = await chat.pipeAndCapture(result, {
      originalMessages: conversation.uiMessages,
    });
    if (response) await conversation.addResponse(response);
  }
  ```
  
With `chat.createSession`, the iterator surfaces it as `turn.handover`;
call `turn.complete()` with no argument on a final handover. The
lower-level `chat.waitForHandover()` and `accumulator.applyHandover()`
are also exported for hand-rolled loops.
- Cache your chat agent's system prompt with Anthropic prompt caching.
`chat.toStreamTextOptions()` now emits the system prompt as a cacheable
message when you opt in, so a large, stable system block is billed at
cache-read rates on every turn instead of full price.
([#3952](#3952))
  
  ```ts
  // at the streamText call site (Anthropic sugar)
  streamText({
...chat.toStreamTextOptions({ cacheControl: { type: "ephemeral" } }),
    messages,
  });
  
  // provider-agnostic equivalent
  chat.toStreamTextOptions({
systemProviderOptions: { anthropic: { cacheControl: { type: "ephemeral"
} } },
  });
  
  // or where the prompt is defined
  chat.prompt.set(SYSTEM_PROMPT, {
providerOptions: { anthropic: { cacheControl: { type: "ephemeral" } } },
  });
  ```
  
Without an option, `system` stays a plain string. Pairs with a
`prepareMessages` cache breakpoint to cache the conversation prefix
across turns too.
- Three fixes for custom agent loops (`chat.customAgent`,
`chat.createSession`, and hand-rolled `MessageAccumulator` loops):
([#3936](#3936))
  
- Continuation runs no longer replay already-answered user messages into
the first turn. The `.in` resume cursor is now seeded before any
listener attaches (the same boot logic `chat.agent` uses), so a chat
that continues after a cancel, crash, or upgrade only sees genuinely new
messages.
- Steering a hand-rolled loop mid-stream no longer wipes the in-flight
assistant response. `chat.pipeAndCapture` now stamps a server-generated
message id on the stream, so a `prepareStep` injection keeps the partial
text instead of replacing the message.
- Task-backed tools (`ai.toolExecute`) now work from custom agent loops:
the parent's session is threaded to the child run, so child tasks can
stream progress into the chat with `chat.stream.writer({ target: "root"
})` instead of failing with "session handle is not initialized".

<details>
<summary>Raw changeset output</summary>

⚠️⚠️⚠️⚠️⚠️⚠️

`main` is currently in **pre mode** so this branch has prereleases
rather than normal releases. If you want to exit prereleases, run
`changeset pre exit` on `main`.

⚠️⚠️⚠️⚠️⚠️⚠️

# Releases
## @trigger.dev/build@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## trigger.dev@4.5.0-rc.7

### Patch Changes

- `@trigger.dev/sdk` now bundles the Trigger.dev agent skills and a
curated snapshot of the docs those skills reference. The skills that
`trigger skills` installs into your coding agent read this content from
node_modules, so the guidance your AI assistant follows is pinned to the
SDK version installed in your project and stays current across upgrades
instead of going stale until the next reinstall.
([#3937](#3937))
- Running a CLI command like `dev`, `deploy`, `preview`, or `update`
before initializing a project no longer crashes with a raw `Cannot find
matching package.json` stack trace. The CLI now detects the missing
project and points you to `npx trigger.dev@latest init` instead.
([#3929](#3929))
- The agent skills installed by `trigger skills` are now namespaced with
a `trigger-` prefix (e.g. `trigger-authoring-tasks`,
`trigger-getting-started`) so they don't collide with unrelated skills
in your coding agent's skills directory. Adds a `trigger-cost-savings`
skill for auditing and reducing compute spend (right-sizing machines,
`maxDuration`, batching, debounce), and `@trigger.dev/sdk` now bundles
the full Trigger.dev documentation so your agent can read the complete,
version-pinned reference directly from node_modules.
([#3970](#3970))
-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`
    -   `@trigger.dev/build@4.5.0-rc.7`
    -   `@trigger.dev/schema-to-json@4.5.0-rc.7`

## @trigger.dev/core@4.5.0-rc.7

### Patch Changes

- The run span API response now includes `cachedCost` and
`cacheCreationCost` on the `ai` object, alongside the existing
`inputCost` / `outputCost` / `totalCost`. `inputCost` reflects only the
non-cached input, so these fields let you reconstruct the full cost
breakdown for prompt-cached calls.
([#3958](#3958))

## @trigger.dev/python@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/sdk@4.5.0-rc.7`
    -   `@trigger.dev/core@4.5.0-rc.7`
    -   `@trigger.dev/build@4.5.0-rc.7`

## @trigger.dev/react-hooks@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## @trigger.dev/redis-worker@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## @trigger.dev/rsc@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## @trigger.dev/schema-to-json@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## @trigger.dev/sdk@4.5.0-rc.7

### Patch Changes

- `@trigger.dev/sdk` now bundles the Trigger.dev agent skills and a
curated snapshot of the docs those skills reference. The skills that
`trigger skills` installs into your coding agent read this content from
node_modules, so the guidance your AI assistant follows is pinned to the
SDK version installed in your project and stays current across upgrades
instead of going stale until the next reinstall.
([#3937](#3937))

- `chat.headStart` now works with the `chat.customAgent` and
`chat.createSession` backends, not only `chat.agent`. The warm step-1
response hands over to your loop the same way it does for a managed
agent. ([#3963](#3963))

    In a `chat.customAgent` loop, consume the handover on turn 0:

    ```ts
    const conversation = new chat.MessageAccumulator();
const { isFinal, skipped } = await conversation.consumeHandover({
payload });
    if (skipped) return; // warm handler aborted, so exit without a turn
    if (isFinal) {
await chat.writeTurnComplete(); // step 1 is the response, no streamText
    } else {
const result = streamText({ model, messages: conversation.modelMessages,
tools });
// Pass originalMessages so the handed-over tool round merges into the
      // step-1 assistant instead of starting a new message.
      const response = await chat.pipeAndCapture(result, {
        originalMessages: conversation.uiMessages,
      });
      if (response) await conversation.addResponse(response);
    }
    ```

With `chat.createSession`, the iterator surfaces it as `turn.handover`;
call `turn.complete()` with no argument on a final handover. The
lower-level `chat.waitForHandover()` and `accumulator.applyHandover()`
are also exported for hand-rolled loops.

- Add `triggerConfig` support to `chat.headStart()` and
`chat.openSession()`, so the auto-triggered handover-prepare run
inherits tags, queue, machine, and other session trigger options the
same way `chat.createStartSessionAction()` does. The `chat:{chatId}` tag
is prepended automatically.
([#3963](#3963))

    ```ts
    export const POST = chat.headStart({
      agentId: "my-agent",
      triggerConfig: { tags: ["org:acme"], queue: "chat" },
run: async ({ chat }) => streamText({ ...chat.toStreamTextOptions(),
model }),
    });
    ```

Because the session is created once on the first head-start turn and is
idempotent on the chat id, this is the only place to set those options
for a head-start chat's lifetime. `chat.createStartSessionAction()` now
also forwards `maxDuration`, `region`, and `lockToVersion` so both
session entry points stay consistent.

- Cache your chat agent's system prompt with Anthropic prompt caching.
`chat.toStreamTextOptions()` now emits the system prompt as a cacheable
message when you opt in, so a large, stable system block is billed at
cache-read rates on every turn instead of full price.
([#3952](#3952))

    ```ts
    // at the streamText call site (Anthropic sugar)
    streamText({
...chat.toStreamTextOptions({ cacheControl: { type: "ephemeral" } }),
      messages,
    });

    // provider-agnostic equivalent
    chat.toStreamTextOptions({
systemProviderOptions: { anthropic: { cacheControl: { type: "ephemeral"
} } },
    });

    // or where the prompt is defined
    chat.prompt.set(SYSTEM_PROMPT, {
providerOptions: { anthropic: { cacheControl: { type: "ephemeral" } } },
    });
    ```

Without an option, `system` stays a plain string. Pairs with a
`prepareMessages` cache breakpoint to cache the conversation prefix
across turns too.

- Three fixes for custom agent loops (`chat.customAgent`,
`chat.createSession`, and hand-rolled `MessageAccumulator` loops):
([#3936](#3936))

- Continuation runs no longer replay already-answered user messages into
the first turn. The `.in` resume cursor is now seeded before any
listener attaches (the same boot logic `chat.agent` uses), so a chat
that continues after a cancel, crash, or upgrade only sees genuinely new
messages.
- Steering a hand-rolled loop mid-stream no longer wipes the in-flight
assistant response. `chat.pipeAndCapture` now stamps a server-generated
message id on the stream, so a `prepareStep` injection keeps the partial
text instead of replacing the message.
- Task-backed tools (`ai.toolExecute`) now work from custom agent loops:
the parent's session is threaded to the child run, so child tasks can
stream progress into the chat with `chat.stream.writer({ target: "root"
})` instead of failing with "session handle is not initialized".

- The agent skills installed by `trigger skills` are now namespaced with
a `trigger-` prefix (e.g. `trigger-authoring-tasks`,
`trigger-getting-started`) so they don't collide with unrelated skills
in your coding agent's skills directory. Adds a `trigger-cost-savings`
skill for auditing and reducing compute spend (right-sizing machines,
`maxDuration`, batching, debounce), and `@trigger.dev/sdk` now bundles
the full Trigger.dev documentation so your agent can read the complete,
version-pinned reference directly from node_modules.
([#3970](#3970))

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

## @trigger.dev/plugins@4.5.0-rc.7

### Patch Changes

-   Updated dependencies:
    -   `@trigger.dev/core@4.5.0-rc.7`

</details>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

.changeset/pre.json

@@ -19,6 +19,7 @@
     "@trigger.dev/sdk": "4.4.6"
   },
   "changesets": [
+    "agent-skills-bundled-in-sdk",
     "agent-skills",
     "ai-prompts",
     "ai-sdk-7-support",
@@ -31,17 +32,22 @@
     "chat-agent-tools",
     "chat-agent",
     "chat-boot-cursor",
+    "chat-headstart-custom-backends",
     "chat-headstart-hydrate",
     "chat-headstart-reasoning",
+    "chat-headstart-trigger-config",
     "chat-history-read-primitives",
     "chat-session-attributes",
     "chat-slim-wire-merge",
     "chat-start-session-action-typed-client-data",
+    "chat-system-prompt-caching",
     "chat-transport-recreate-missing-session",
     "cli-deploy-skip-rewrite-timestamp",
+    "cli-dev-without-project",
     "cli-init-ai-tooling",
     "coerce-concurrency-key-to-string",
     "create-session-stop-continuation",
+    "custom-agent-loop-fixes",
     "dequeue-latency-histogram",
     "duplicate-task-ids",
     "env-vars-tracing-forceflush-typecheck",
@@ -66,7 +72,9 @@
     "runs-list-region-filter",
     "s2-batch-transform-linger-fix",
     "sessions-primitive",
+    "span-api-cached-cost",
     "trigger-client",
+    "trigger-skill-namespace-and-docs",
     "trigger-skills-installer",
     "unflatten-attributes-conflict",
     "warm-start-external-trace-context-leak"