Trellis
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ENGINEERING TUTOR • L5 / L6 ANDROID

Your personal tutor for senior engineering interviews.

Trellis watches how you code, debug, and design systems. When you're stuck, Rook gives you the next nudge, not the answer.

Live problem practice opens after the lab engine ships. You can take the diagnostic now.

LIVE INCIDENT SIMULATION
Checkout Fell 17% OvernightRelease 8.12
-17.2% conversion+0.1% crash rate
CheckoutViewModel.ktKotlin
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class CheckoutViewModel(private val repo: CheckoutRepository) : ViewModel() {
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private val _state = MutableStateFlow<CheckoutState>(CheckoutState.Idle)
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val state = _state.asStateFlow()
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fun pay(order: Order) {
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_state.value = CheckoutState.Processing
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// Unscoped coroutine detached from UI lifecycle
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GlobalScope.launch {
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repo.submit(order)
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}
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// Structured concurrency scope binding:
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viewModelScope.launch {
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repo.submit(order)
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}
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}
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}
Rook Socratic Observation

“Look at line 8: who owns the lifetime of this coroutine when the user presses Back during network latency?”

Hypothesis: Orphaned job causing duplicate 409 Conflict
Interactive Sandbox Ready

Run unit test assertions, inspect Logcat streams, and analyze HTTP status traces.

Cognitive Tutoring

A tutor that can see your reasoning.

Rook doesn't wait for you to copy-paste error messages into a chat window. It observes your test runs, network traces, and code mutations directly in the editor.

  • • In-gutter cognitive prompts tied to AST mutations
  • • Coroutine lifecycle leak detection
  • • Deterministic evaluation runner with zero hallucination
TELEMETRY OBSERVER • ACTIVE COROUTINE SCOPE
[Logcat 18:02:11] Dispatchers.Default Job #104 orphan detected on ViewModel.onCleared()
[Rook Level 1 Clue] ViewModelScope binds jobs directly to lifecycle cancellation.
PRODUCTION INCIDENT SUITEL5 / L6 RUBRIC
1. Checkout 17% DropLifecycle Leak
2. Compose Infinite JankSnapshot State Invalidation
3. Offline Sync Split-BrainDistributed Clock Conflict
Unstructured Scenarios

Practice the problems that don't come with instructions.

Real staff interviews don't ask you to invert a binary tree. They hand you a production checkout regression with 17% conversion drop and ask: find it, explain it, fix it.

Cognitive Scaffolding

Help that learns when to disappear.

Every prompt from Rook is calibrated to your independent problem-solving capacity. As your mastery deepens, the scaffolding recedes.

STAGE 1: GUIDED

Socratic nudges point to suspicious lifecycle scopes, memory dumps, and network traces.

STAGE 2: MINIMAL

Rook observes silently unless multiple test runs produce circular deadlocks.

STAGE 3: INDEPENDENT

Rook steps back entirely. Your solution is verified against production test fixtures under time pressure.

Curriculum Rigor

From Kotlin details to Staff-level architecture.

Comprehensive real-world scenarios covering Android memory management, Compose composition trees, offline sync architectures, and executive tradeoff communication.

Kotlin Core
Coroutines, Flow, Types
Android Framework
Lifecycle, Process Death
Jetpack Compose
Recomposition, State
Performance
Memory, Systrace, Jank
Mobile Systems
Sync, Storage, Cache
Staff Leadership
RFCs, Tradeoffs, SLAs

The interview room shouldn't be your first rehearsal.

Join experienced engineers preparing for L5+ and L6+ roles at top technology companies.