Architecture

The full document is docs/01_ARCHITECTURE.md; the IPC details are in docs/07_IPC.md.

flowchart LR
  subgraph game["Game process (only games the user enabled)"]
    G["Game"] -- "present and API calls" --> O["FrameLedger.Overlay.dll: hooks"]
  end
  O -- "fixed-size frame records" --> R[("shared-memory ring")]
  R -- "drained every 100 ms" --> A["FrameLedger.Agent.exe"]
  A -- "sessions, frames, sensors" --> DB[("ledger.db (SQLite)")]
  DB --> UI["FrameLedger.exe (the App)"]
  UI -- "named pipe: commands" --> A
  A -- "named pipe: events" --> UI

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The processes

What	Runs	Does
FrameLedger.exe — src/FrameLedger.App	as the user	The WPF app: library, sessions, charts, settings. Reads SQLite; talks to the agent over the pipe.
FrameLedger.Agent.exe — src/FrameLedger.Agent	as the user; as administrator only if the user opts in	Watches for tracked games, runs the anti-cheat guard, injects, drains the ring, reads sensors once a second, writes SQLite. Closing the App never stops it.
FrameLedger.Overlay.dll — src/native/FrameLedger.Overlay	inside the game	Hooks presentation (DXGI for Direct3D 11 and 12, and OpenGL) and the upscaler, frame-generation and ray-tracing calls, and writes one record per frame into the ring. A hook never blocks, allocates, logs or throws. It draws nothing on screen.
FrameLedger.VkLayer.dll — src/native/FrameLedger.VkLayer	inside a Vulkan game	An implicit Vulkan layer instead of hooks, active only in a game FrameLedger starts.
FrameLedger.Guard.dll, FrameLedger.NvapiBridge.dll, FrameLedger.ProcessStats.dll	inside the agent, never a game	The anti-cheat guard (required), NVIDIA's extra sensors (optional), and the game's own memory read from outside it (optional). An optional one missing makes its fields N/A.

src/FrameLedger.CaptureHost is a developer tool and is never shipped.

Two tiers

• Tier 1 — measured. The user switched hooking on for the game, and the guard found nothing: every frame is recorded.
• Tier 2 — recorded only. No hooking: the session keeps its duration, the PC's sensors, the game's memory, its display mode, and why it was not measured. Every frame figure is N/A, never an estimate.

There is no third rung: without the hook there is no frame measurement at all.

How a frame gets to the screen

1. The agent's watcher sees a tracked game's executable start (by full path, once a second).
2. Hooking off, or not consented: the session is Tier 2.
3. The guard checks the game's process tree, the PC's drivers and services, its title lists and the game's install folder. Any finding, or any doubt, refuses: Tier 2, with the reason.
4. On a pass, the guard injects the Overlay with the documented LoadLibraryW, under its real name.
5. The Overlay installs its hooks, creates the ring and publishes a handshake; the agent checks the layout version and the build id before it reads anything.
6. The agent drains the ring every 100 ms and checks the game again every 30 seconds; a finding unhooks.
7. When the game exits, the agent finalizes the session and writes it to SQLite in one transaction; the App reads it.

Where data lives

%LOCALAPPDATA%\FrameLedger: ledger.db (WAL mode), logs\, crashdumps\, and tmp\ for a session in progress (its .partial file). The App installs separately, in %LOCALAPPDATA%\FrameLedger.App.