fix: respect opts.debug in installV3ShadowPiercer (fixes #1996)

[kagura-agent]

Problem

installV3ShadowPiercer declares a debug?: boolean option in V3ShadowPatchOptions, but ignores it — DEBUG is hardcoded to true:

// hardcoded debug (remove later if desired)
const DEBUG = true;

This means console.info("[v3-piercer] attachShadow", ...) fires on every attachShadow call regardless of what the caller passes, and the debug field in V3ShadowPatchOptions is effectively dead API.

Fix

const DEBUG = opts.debug ?? false;

One-line change. Defaults to false (no debug noise) and respects the caller's choice when explicitly set.

Closes #1996.

---

Summary by cubic

Respect opts.debug in installV3ShadowPiercer by replacing the hardcoded DEBUG = true with const DEBUG = opts.debug ?? false. This removes noisy logs by default and lets callers enable debugging when needed (fixes #1996).

^{Written for commit 5c2f895. Summary will update on new commits. Review in cubic}

[changeset-bot]

🦋 Changeset detected

Latest commit: 5c2f895

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@browserbasehq/stagehand	Patch
@browserbasehq/stagehand-evals	Patch
@browserbasehq/stagehand-server-v3	Patch
@browserbasehq/stagehand-server-v4	Patch

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[github-actions]

This PR is from an external contributor and must be approved by a stagehand team member with write access before CI can run.
Approving the latest commit mirrors it into an internal PR owned by the approver.
If new commits are pushed later, the internal PR stays open but is marked stale until someone approves the latest external commit and refreshes it.

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant Caller as Calling Service/Script
    participant Piercer as installV3ShadowPiercer
    participant DOM as Element.prototype
    participant Console as Browser Console

    Note over Caller,DOM: Initialization Phase

    Caller->>Piercer: installV3ShadowPiercer(opts)
    Piercer->>Piercer: CHANGED: Evaluate DEBUG via opts.debug ?? false
    Piercer->>DOM: Patch attachShadow() logic
    DOM-->>Piercer: Done
    Piercer-->>Caller: Void

    Note over Caller,DOM: Runtime Execution Phase

    participant App as Web Application
    App->>DOM: element.attachShadow(init)
    
    alt DEBUG is true
        DOM->>Console: NEW: Log "[v3-piercer] attachShadow"
    else DEBUG is false
        Note over DOM,Console: No logging output
    end

    DOM->>DOM: Execute original attachShadow
    DOM->>DOM: Track shadow root in window.__v3ShadowRoots
    DOM-->>App: shadowRoot

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