feat(runtime): Phase B - live VRAM budget for native admission

[hardcoreerik]

What this is

Implementation PR for the live-budget half of Phase B of the native runtime spec. Ships the well-grounded half of Phase B now; explicitly defers the other half rather than shipping an ungrounded generalization (see below).

Please review before merging — same discipline as Phase A (#70): opt-in native runtime, but this changes what admission decisions are actually based on.

What ships

New NativeVramProbe.TryQueryLiveNvidiaBudget() — a live nvidia-smi subprocess query (memory.total, memory.used), reusing the exact subprocess-CSV pattern already proven safe in OrchestratorSetup/Services/HardwareDetector.QueryNvidiaSmi, but for live current usage instead of a one-time install-time total.

The gap this closes: before this PR, there was no "how much VRAM is free right now" query anywhere in the running app. The only VRAM detection that existed lives in a different project (OrchestratorSetup, the installer), runs once at install time, and only measures total capacity — never live availability. That's exactly why MainWindow/HiveService's budget providers hardcoded ReservedBytes: 0.

Wiring: MainWindow and HiveService now pass the budget-building method itself as budgetProvider, not a closed-over one-time snapshot — RuntimeOrchestrator.EnsureAdmitted already calls _budgetProvider() fresh on every admission (confirmed from Phase A), so this makes admission decisions genuinely live instead of stale-at-construction-time. Both sites fall back to the pre-Phase-B static-total behavior when the live probe is unavailable (non-NVIDIA GPU, nvidia-smi missing) — never worse than before, only ever more accurate.

Small correctness fix along the way: widened Func<VramBudget>? to Func<VramBudget?>? in RuntimeOrchestrator/IRoleRuntime. The declared type didn't match reality — EnsureAdmitted already null-coalesces/throws on a null result and GetReservationSnapshot already null-checks it — and passing a genuinely nullable-returning method directly surfaced a real CS8621 nullability warning that the old budget is null ? null : () => budget pattern had been silently working around.

What's deliberately deferred (and why)

The spec's Phase B also calls for a "KV/rs-cache-aware cost estimate" on OrcScheduler.EstimateRequiredBytes (currently just GGUF file size). I investigated adding AdapterManager.SequenceHardLimit * ~50MB/slot as a fixed reservation — that number is already documented in AdapterManager.cs's own comments, empirically confirmed on real hardware.

Rejected: that overhead is specific to hybrid/recurrent-architecture models (Qwen3.5's Gated Delta Net layers) — it does not apply to plain-transformer models, which are the common case. RuntimeModelAsset has no architecture metadata to distinguish the two. A flat, always-on addition would over-reserve VRAM for every admission regardless of what's actually being loaded, risking real regressions — denying legitimate admissions on modest-VRAM boxes that used to fit fine. It would also break several OrcSchedulerTests that assert exact-fit admission.

Shipping a plausible-looking but ungrounded generalization from one empirical data point felt worse than shipping the well-grounded half now and leaving this explicitly open. Will need real GGUF architecture metadata (not currently exposed anywhere) to do properly.

Verification

• All 7 consumer projects build clean (Avalonia, Daemon, NativeRuntime, UnitTests, HeadlessTests, UITests, SwarmCli, ContextFabricBench) — 0 warnings, 0 errors.
• Full OrchestratorIDE.UnitTests suite: 596 passed, 0 failed, 4 skipped (same pre-existing THEORC_TEST_GGUF-gated skips, unaffected by this change).
• Two new tests for NativeVramProbe — tolerant of "no GPU" environments (asserts invariants when non-null, doesn't require a GPU to pass).
• Genuinely verified on real hardware: this dev box has a real NVIDIA GPU (RTX 5070 Ti). Ran the probe via a throwaway scratch program (not committed) and confirmed its output matched an independent manual nvidia-smi reading taken beforehand (~15.9 GB total, ~3.7 GB used, ~12.2 GB available) — this is a genuine /verify, not just a passing unit test.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Native runtime admission now evaluates available VRAM budgets using live NVIDIA GPU information when available.
  • Falls back to configured VRAM limits when live GPU data cannot be retrieved.
  • VRAM budgets are refreshed for each admission, improving accuracy during changing workloads.

• Bug Fixes

  • Prevented stale VRAM readings from affecting runtime admission decisions.

• Tests

  • Added coverage for reliable, repeatable live VRAM detection and fallback scenarios.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 03b3df05-b177-4696-b604-61c7816155b0

📥 Commits

Reviewing files that changed from the base of the PR and between 48874b7 and 00081b0.

📒 Files selected for processing (2)

• OrchestratorIDE.Avalonia/MainWindow.axaml.cs
• OrchestratorIDE/Core/Runtime/NativeVramProbe.cs

📝 Walkthrough

Walkthrough

Native runtime budget providers now resolve nullable budgets per admission. A shared NVIDIA probe queries live VRAM with timeout and failure handling, while the daemon falls back to configured capacity. Tests cover probe results and repeatability.

Changes

Native VRAM budget evaluation

Layer / File(s)	Summary
Nullable budget contract and NVIDIA probe OrchestratorIDE/Core/Runtime/IRoleRuntime.cs, OrchestratorIDE/Core/Runtime/RuntimeOrchestrator.cs, OrchestratorIDE/Core/Runtime/NativeVramProbe.cs	Budget providers now return nullable VramBudget values. NativeVramProbe queries nvidia-smi, parses total and used memory, enforces a timeout, and returns null on failure.
Per-admission budget wiring and fallback OrchestratorIDE.Daemon/HiveService.cs, OrchestratorIDE.Avalonia/MainWindow.axaml.cs	Native runtime construction passes method delegates for fresh budget evaluation. The daemon prefers live NVIDIA data and falls back to configured VRAM.
Probe build and validation OrchestratorIDE.NativeRuntime/OrchestratorIDE.NativeRuntime.csproj, OrchestratorIDE.UnitTests/NativeVramProbeTests.cs	The shared probe is added to the native runtime build, with tests for sane nullable results and repeated calls without exceptions.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• hardcoreerik/TheOrc#70: Modifies native admission-control wiring around scheduler and budget-provider behavior.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: enabling live VRAM budget checks for native admission in Phase B.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/native-runtime-vram-budget

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@OrchestratorIDE.Avalonia/MainWindow.axaml.cs`:
- Around line 2297-2304: Update TryBuildNativeHiveBudget to call
NativeVramProbe.TryQueryLiveNvidiaBudget() first and return its live budget when
available. If the probe does not produce a result, preserve the existing
fallback to the statically detected total, including its current ReservedBytes
behavior.

In `@OrchestratorIDE/Core/Runtime/NativeVramProbe.cs`:
- Around line 65-72: Update the process-reading flow around NativeVramProbe’s
StandardOutput handling so ReadToEnd is initiated asynchronously before
enforcing the QueryTimeout. Wait for process exit within the timeout, kill the
process and return null on timeout, then retrieve the completed output only
after successful exit without introducing an indefinite synchronous read.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: fab9866c-0d57-43de-a778-33ee8523e128

📥 Commits

Reviewing files that changed from the base of the PR and between ea6aaf9 and 48874b7.

📒 Files selected for processing (7)

• OrchestratorIDE.Avalonia/MainWindow.axaml.cs
• OrchestratorIDE.Daemon/HiveService.cs
• OrchestratorIDE.NativeRuntime/OrchestratorIDE.NativeRuntime.csproj
• OrchestratorIDE.UnitTests/NativeVramProbeTests.cs
• OrchestratorIDE/Core/Runtime/IRoleRuntime.cs
• OrchestratorIDE/Core/Runtime/NativeVramProbe.cs
• OrchestratorIDE/Core/Runtime/RuntimeOrchestrator.cs

[hardcoreerik]

Both findings confirmed and fixed in 00081b0:

1. MainWindow live-probe gap — real bug, isolated to MainWindow.axaml.cs (HiveService's version was already correct). TryBuildNativeHiveBudget() now actually calls NativeVramProbe.TryQueryLiveNvidiaBudget() first, matching what the adjacent comment already claimed.
2. ReadToEnd() deadlock hazard — real bug. Replaced with a CancellationTokenSource(QueryTimeout) bounding both the async read and async exit under one shared deadline via Task.WaitAll, killing the process on cancellation.

Both re-verified for real against this machine's GPU (not just unit tests): 5 repeated calls through the fixed probe returned consistent correct values in 62-84ms each, confirming the deadlock fix didn't regress normal-case latency.

@coderabbitai review

[coderabbitai]

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

git show --stat --oneline 00081b0c
git diff 00081b0c^ 00081b0c -- \
  OrchestratorIDE.Avalonia/MainWindow.axaml.cs \
  OrchestratorIDE/Core/Runtime/NativeVramProbe.cs

ast-grep outline OrchestratorIDE.Avalonia/MainWindow.axaml.cs --items all --match 'TryBuildNativeHiveBudget|BuildExperimentalNativeRoleRuntime'
ast-grep outline OrchestratorIDE/Core/Runtime/NativeVramProbe.cs --items all --match 'NativeVramProbe|TryQueryLiveNvidiaBudget'

rg -n -C 5 '\bTryQueryLiveNvidiaBudget\s*\(' \
  OrchestratorIDE.Avalonia/MainWindow.axaml.cs \
  OrchestratorIDE.Daemon/HiveService.cs \
  OrchestratorIDE/Core/Runtime/NativeVramProbe.cs \
  OrchestratorIDE.UnitTests/NativeVramProbeTests.cs \
  OrchestratorIDE/Core/Runtime/RuntimeOrchestrator.cs

Length of output: 9393

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🏁 Script executed:

#!/bin/bash
set -euo pipefail

ast-grep outline OrchestratorIDE/Core/Runtime/NativeVramProbe.cs --items all --view expanded
ast-grep outline OrchestratorIDE.Avalonia/MainWindow.axaml.cs --items all --view expanded --match 'TryBuildNativeHiveBudget'

nl -ba OrchestratorIDE/Core/Runtime/NativeVramProbe.cs | sed -n '1,180p'
nl -ba OrchestratorIDE.Avalonia/MainWindow.axaml.cs | sed -n '2280,2355p'

fd --type f --glob '*.csproj' . | sort | while IFS= read -r project; do
  if rg -q 'OrchestratorIDE.NativeRuntime|TargetFramework|TargetFrameworks' "$project"; then
    echo "===== $project ====="
    rg -n -C 2 '<TargetFrameworks?>|OrchestratorIDE\.NativeRuntime' "$project" || true
  fi
done

rg -n -C 3 '\bQueryTimeout\b|\bTask\.WaitAll\s*\(|\bWaitForExitAsync\s*\(' \
  OrchestratorIDE/Core/Runtime/NativeVramProbe.cs

Length of output: 1480

---

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo '===== OrchestratorIDE/Core/Runtime/NativeVramProbe.cs ====='
awk '{ printf "%6d  %s\n", NR, $0 }' OrchestratorIDE/Core/Runtime/NativeVramProbe.cs | sed -n '1,180p'

echo '===== OrchestratorIDE.Avalonia/MainWindow.axaml.cs (budget method) ====='
awk '{ printf "%6d  %s\n", NR, $0 }' OrchestratorIDE.Avalonia/MainWindow.axaml.cs | sed -n '2280,2355p'

echo '===== target frameworks / NativeRuntime references ====='
fd --type f --extension csproj . | sort | while IFS= read -r project; do
  if rg -q '<TargetFramework|<TargetFrameworks|OrchestratorIDE\.NativeRuntime' "$project"; then
    echo "----- $project -----"
    rg -n -C 2 '<TargetFrameworks?>|OrchestratorIDE\.NativeRuntime' "$project" || true
  fi
done

echo '===== related timeout/wait occurrences ====='
rg -n -C 4 '\bQueryTimeout\b|\bTask\.WaitAll\s*\(|\bWaitForExitAsync\s*\(' \
  OrchestratorIDE/Core/Runtime/NativeVramProbe.cs

Length of output: 19524

---

@hardcoreerik Confirmed: both findings are addressed in 00081b0c.

• MainWindow.TryBuildNativeHiveBudget() now correctly prefers a fresh live NVIDIA budget and retains the detected-total fallback.
• NativeVramProbe.TryQueryLiveNvidiaBudget() now places stdout reading and process exit under one three-second cancellation deadline, killing the process tree on timeout.

No further issues found in this follow-up review. 🐇✅

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