feat(sandbox): add session sandbox controls

[marius-kilocode]

Sandboxing can currently only be controlled through persistent configuration, so changing it affects every session and clients have no reliable way to show or change the effective runtime state. This is especially confusing when a persisted default remains active without a visible control.

This adds a session-local sandbox override on top of the persistent experimental.sandbox default. The CLI exposes authenticated status and toggle endpoints plus change events, serializes transitions and cleanup per session, keeps overrides isolated by directory, and clears all overrides when a session is removed. Tool and MCP execution use the effective state while preserving the existing filesystem and network policies.

The TUI adds /sandbox, an active-state indicator, and toggle feedback. VS Code adds a feature-gated prompt control that works from an empty composer and Agent Manager worktrees, waits for transitions before sending prompts, fails closed when toggling cannot be confirmed, and reconciles HTTP responses with SSE updates without stale state.

Follow-up: #11630

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (38 files)

• .changeset/toggle-tui-sandbox.md
• packages/kilo-sandbox/src/context.ts
• packages/kilo-sandbox/src/index.ts
• packages/kilo-vscode/src/KiloProvider.ts
• packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts
• packages/kilo-vscode/src/agent-manager/types.ts
• packages/kilo-vscode/src/kilo-provider-utils.ts
• packages/kilo-vscode/src/services/cli-backend/connection-utils.ts
• packages/kilo-vscode/tests/unit/connection-utils.test.ts
• packages/kilo-vscode/tests/unit/kilo-provider-load-messages.test.ts
• packages/kilo-vscode/tests/unit/kilo-provider-utils.test.ts
• packages/kilo-vscode/tests/unit/prompt-input-connection-guard.test.ts
• packages/kilo-vscode/tests/unit/prompt-input-utils.test.ts
• packages/kilo-vscode/webview-ui/src/components/chat/PromptInput.tsx
• packages/kilo-vscode/webview-ui/src/components/chat/prompt-input-utils.ts
• packages/kilo-vscode/webview-ui/src/types/messages/extension-messages.ts
• packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts
• packages/opencode/src/cli/cmd/tui/plugin/internal.ts
• packages/opencode/src/kilocode/plugins/sandbox.tsx
• packages/opencode/src/kilocode/sandbox/event.ts
• packages/opencode/src/kilocode/sandbox/policy.ts
• packages/opencode/src/kilocode/server/httpapi/groups/sandbox.ts
• packages/opencode/src/kilocode/server/httpapi/handlers/sandbox.ts
• packages/opencode/src/kilocode/server/httpapi/server.ts
• packages/opencode/src/server/routes/instance/httpapi/api.ts
• packages/opencode/src/session/session.ts
• packages/opencode/src/session/tools.ts
• packages/opencode/test/kilocode/sandbox/config-network.test.ts
• packages/opencode/test/kilocode/sandbox/sdk-config.test.ts
• packages/opencode/test/kilocode/sandbox/session.test.ts
• packages/opencode/test/kilocode/sandbox/state.test.ts
• packages/opencode/test/kilocode/sandbox/tui.test.ts
• packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
• packages/sdk/js/src/gen/types.gen.ts
• packages/sdk/js/src/v2/gen/sdk.gen.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json
• script/check-model-tool-network.ts

---

_{Reviewed by gpt-5.4-20260305 · Input: 253.9K · Output: 20.7K · Cached: 1.9M}

_{Review guidance: REVIEW.md from base branch main}