fix(agent-harness): keep the compressed window when a steering note is injected

[andyst-dev]

Fixes #1808

Problem

AiSdkAgentRunner.policyPrepareStep composed the conversation with an if (injectNote) ... else if (merged.messages) chain. When a policy injected a steering note (CompletionGatePolicy) at the same step that another policy produced a compressed window (CompressionPolicy), the note branch rebuilt the message list from the uncompressed original (msgs ?? messages) and discarded the compression — bypassing the hard per-request context clamp added for #1574 in #1578.

Root cause

if (merged.injectNote) {
  out.messages = [ ...(msgs ?? messages), note ];   // ignores merged.messages
} else if (merged.messages) {
  out.messages = merged.messages.map(toModelMessage);
}

mergeDirectives() legitimately returns both messages and injectNote, but the note branch appended to the original msgs.

Fix

When both fire, compute a single baseMessages = the compressed window if present, else the original, and append the note to it:

const baseMessages = merged.messages
  ? merged.messages.map(toModelMessage)
  : (msgs ?? messages);

The note branch now spreads baseMessages; the non-note branch uses it too.

Validation

Regression test in ai-sdk-agent-runner.compression.e2e.spec.ts drives CompressionPolicy (tiny window) + a note-injecting CompletionGatePolicy together and asserts the model sees the steering note without the full-size raw tool result:

• without the fix the test is RED (the cached prompt carries the whole readFile result)
• with the fix the test is GREEN (4/4 pass, including the 3 pre-existing compression tests)

No real model/network involved — mocked ai/test model only.

[kody-ai]

Code Review Completed! 🔥

The code review was successfully completed based on your current configurations.

Kody Guide: Usage and Configuration

Interacting with Kody

• Request a Review: Ask Kody to review your PR manually by adding a comment with the `@kody start-review` command at the root of your PR.

• Provide Feedback: Help Kody learn and improve by reacting to its comments with a 👍 for helpful suggestions or a 👎 if improvements are needed.

Current Kody Configuration

Review Options

The following review options are enabled or disabled:

Options	Enabled
Bug	✅
Performance	✅
Security	✅
Business Logic	✅

Access your configuration settings here.

[kody-ai]

🤔 Insufficient Task Context

I found a task linked to this PR, but it only contains minimal information (title only, no description or acceptance criteria). To perform a meaningful business rules validation, I need more details.

🔍 What I need to validate:

• Business requirements and acceptance criteria
• Expected behavior and business rules
• Edge cases and constraints to consider

💡 How to improve the task context:

• Add a description to the linked ticket
• Include acceptance criteria or business rules
• Describe the expected behavior after the change

⚠️ Important:

A task title alone is not sufficient to determine whether the implementation is correct or complete.

[kody-ai]

Code Review Completed! 🔥

The code review was successfully completed based on your current configurations.

Kody Guide: Usage and Configuration

Interacting with Kody

• Request a Review: Ask Kody to review your PR manually by adding a comment with the `@kody start-review` command at the root of your PR.

• Provide Feedback: Help Kody learn and improve by reacting to its comments with a 👍 for helpful suggestions or a 👎 if improvements are needed.

Current Kody Configuration

Review Options

The following review options are enabled or disabled:

Options	Enabled
Bug	✅
Performance	✅
Security	✅
Business Logic	✅

Access your configuration settings here.

[kody-ai]

🤔 Insufficient Task Context

I found a task linked to this PR, but it only contains minimal information (title only, no description or acceptance criteria). To perform a meaningful business rules validation, I need more details.

🔍 What I need to validate:

• Business requirements and acceptance criteria
• Expected behavior and business rules
• Edge cases and constraints to consider

💡 How to improve the task context:

• Add a description to the linked ticket
• Include acceptance criteria or business rules
• Describe the expected behavior after the change

⚠️ Important:

A task title alone is not sufficient to determine whether the implementation is correct or complete.