Fix scrollable native REPL

[Paul (hutch3232)]

• Closes Native REPL 'View as scrollable element' not working #25609

I had GitHub Copilot hammer at this one for quite awhile. I tested it and it does in fact work for me. Copilot did write some tests but I wanted to start with this to see if a fix like this could even be accepted.

[Bill Schnurr (bschnurr)]

🔒 Automated review in progress — Bill Schnurr (@bschnurr) is auto-reviewing this PR.

[Bill Schnurr (bschnurr)]

Warning · Non-blocking recommendation

Add a native-REPL regression test using long output to verify that the notebook output remains non-scrollable through VS Code's notebook API.

[unverified]

[Bill Schnurr (bschnurr)]

Verification: The relevant tests could not be fully run in the isolated environment; this review is not fully verified.

Result: could-not-verify

Summary: The PR changes REPL output construction to disable scrolling, but adds no tests covering that behavior. Existing REPL tests stub `createReplController` and do not exercise its output metadata. The verification container could not start, and local execution was unauthorized, so no meaningful tests ran. Static inspection identified a concrete coverage gap.

Test runs: 1 not run

• ⚠️ Not run | Verification preflight and test discovery | git status --short && git diff --stat upstream/main...HEAD && git diff --name-status upstream/main...HEAD && git diff upstream/main...HEAD -- src\client\repl\replController.ts && node -e "const p=require('./package.json'); console.log(JSON.stringify(p.scripts,null,2))" && rg -n "createReplController|replController|scrollable|NotebookCellOutputItem.stdout" src --glob "test.ts" --glob "test.tsx" --glob "spec.ts" --glob "spec.tsx" || true && if [ -d node_modules ]; then echo NODE_MODULES_PRESENT; else echo NODE_MODULES_MISSING; fi

⚠️ Verification preflight and test discovery diagnostic output

Container verification could not start: no trusted sandbox image is configured for microsoft/vscode-python. Local execution was not authorized.

[Bill Schnurr (bschnurr)]

Approved via Review Center.

[Bill Schnurr (bschnurr)]

Verification: The relevant tests could not be fully run in the isolated environment; this review is not fully verified.

Result: needs-more-tests

Summary: Targeted verification could not run because no trusted sandbox image is configured for `microsoft/vscode-python`. The existing Native REPL tests stub `createReplController`, so they do not exercise the changed output construction. No new tests were added for the new stdout and non-scrollable metadata behavior.

Test runs: 1 not run

• ⚠️ Not run | Dependency and targeted-test discovery | git status --short && git diff --name-status upstream/main...HEAD && git diff --stat upstream/main...HEAD && printf '\n--- package scripts ---\n' && node -e "const p=require('./package.json'); console.log(JSON.stringify(p.scripts,null,2))" && printf '\n--- dependency state ---\n' && if [ -d node_modules ]; then echo 'node_modules=present'; else echo 'node_modules=missing'; fi && printf '\n--- relevant tests ---\n' && rg -n --glob 'test.ts' --glob 'spec.ts' "replController|createReplController|scrollable|NotebookCellOutputItem.stdout" src | head -200

⚠️ Dependency and targeted-test discovery diagnostic output

Container verification could not start: no trusted sandbox image is configured for microsoft/vscode-python, and local execution was not authorized.