S1Atlas

A local, offline developer-intelligence platform for Schedule I mod development. It turns the game’s compiled internals into a searchable, provenance-tracked map for both human developers and coding agents.

Disclaimer: S1Atlas is an unofficial, fan-made developer tool. It is not affiliated with, endorsed by, or connected to the developers or publishers of Schedule I. It requires you to supply your own legitimately obtained copy of the game, and it neither includes nor distributes any game assets, binaries, or decompiled output. All generated data stays local on your machine. It is provided for interoperability, modding, and educational purposes under the MIT License. Game type and member names that appear in the documentation are illustrative examples only; no game code or decompiled output is included.

What it does

Point S1Atlas at your installed copy of Schedule I and it:

• Fingerprints the build and tracks every version you scan, immutably.
• Extracts and decompiles the IL2CPP game assemblies through a verified Cpp2IL + ILSpy pipeline.
• Indexes every type, method, field, and relationship, searchable by name, with decompiled source, callers, callees, and references.
• Traces static engine/BCL relationships so you can ask who calls a Unity or framework API and who reads or writes a field, across the verified game index and explicitly selected local reference collections.
• Diffs builds so you can see exactly what a game update changed.
• Deep-indexes S1API and S1MAPI so you can check the modding API before patching the game directly.
• Indexes explicitly selected local reference-mod collections so prior-art symbols and relationships can be queried beside the verified game index.
• Recovers native bodies for stubbed methods so a game method that decompiles to nothing but a throw null stub can be mapped to its native GameAssembly.dll address, with bounded, provenance-stamped evidence of what it calls and reads, recovered statically without running the game.
• Investigates behavior-ownership seams and plans runtime proofs so you can find which type actually owns a behavior, with explicit coverage and negative results, and get a bounded, read-only plan to confirm it at runtime when static evidence cannot.
• Serves the same knowledge three ways: a CLI, a read-only MCP server for coding agents, and a local read-only web app (s1atlas serve).

Every answer is labeled by provenance, FACT for extracted and DERIVED for computed, and traced to the exact build. S1Atlas reports only what it can prove and stays explicit about what it cannot.

Example: “what changes the player’s cash?”

Examples assume the installed s1atlas tool (see Quick start).

# find it
> s1atlas search "ChangeCashBalance"
ScheduleOne.Money.MoneyManager::ChangeCashBalance(System.Single, System.Boolean, System.Boolean)

# read the decompiled source
> s1atlas source "MoneyManager.ChangeCashBalance"

# see every call site in the game
> s1atlas callers "MoneyManager.ChangeCashBalance"

Requirements

• Windows 10 or later
• .NET 8 SDK
• A local, legitimately owned Schedule I installation (for real scans)

Quick start

# pack and install both tools from this checkout
dotnet pack S1Atlas.sln --configuration Release --output ./.tool-dev/packages
dotnet tool install S1Atlas.Cli --tool-path ./.tool-dev/tools --add-source ./.tool-dev/packages
dotnet tool install S1Atlas.Mcp --tool-path ./.tool-dev/tools --add-source ./.tool-dev/packages

# put ./.tool-dev/tools on PATH, then verify the install
s1atlas --version
s1atlas-mcp --version

# scan your installation
s1atlas scan --game-path "C:\Program Files (x86)\Steam\steamapps\common\Schedule I"

# extract + index the current build, then query it
s1atlas extract
s1atlas index
s1atlas search "Player" --limit 20
s1atlas call-sites "UnityEngine.AI.NavMeshAgent.CompleteOffMeshLink"
s1atlas field-refs "MoneyManager.cashBalance" --writers

# validate and index a local reference-mod collection selected by a manifest
s1atlas reference collections validate "C:\path\to\reference-manifest.json"
s1atlas reference index "C:\path\to\reference-manifest.json"
s1atlas search "ModEntry" --scope reference --collection qol

# browse the local read-only web app (ranked search, symbols, builds, diffs)
s1atlas serve

The full command walkthrough, every option, the MCP server, and the agent skill are in docs/USAGE.md.

Interfaces

• CLI: scan, extract, index, search / type / method / source / refs / callers / callees / call-sites / field-refs / callable, investigate-seam, recover-native-body, diff, the scenes / scene / game-object / prefab / component graph queries, upstream, serve, and open.
• Read-only MCP server: the Schedule I Installed query surface (symbols, source, relationships, call sites, field references, callable surface, scenes), investigate_seam with read-only native evidence, plan_runtime_proof, S1API/S1MAPI queries, and completed local reference-collection queries, for coding agents (run the installed s1atlas-mcp with no arguments).
• Local web app: s1atlas serve starts a loopback-only, read-only web app with ranked search, symbol pages, builds, environment, and diffs.
• Agent skill: an evidence-first usage methodology at skills/s1atlas/SKILL.md.

How it works

S1Atlas.Core           Domain records and interfaces
S1Atlas.Extraction     Read-only discovery, hashing, dependency, local Steam metadata detection, and Cpp2IL orchestration
S1Atlas.Indexing       ILSpy decompilation, Roslyn source/symbol indexing, relationships, scene intelligence, and index queries
S1Atlas.NativeRecovery Bounded native-body recovery over GameAssembly.dll for stubbed IL2CPP methods
S1Atlas.Storage        Checksummed migrations and transactional SQLite persistence
S1Atlas.Application    Shared read-only composition and Schedule I Installed build authority
S1Atlas.Cli            Human and machine-readable command-line interface
S1Atlas.Mcp            Read-only MCP stdio server for Schedule I Installed and completed local reference queries

S1Atlas treats the game install and Steam manifest as read-only input. Extraction runs Cpp2IL in isolation and promotes only results that pass the validation policy. Native-body recovery reads GameAssembly.dll and global-metadata.dat and never launches or mutates the game. CLI, MCP, and web-app queries use the same verified index.

Reference collections are local and CLI-indexed. Each completed collection records its selected mods, hashes, and Schedule I base index; MCP exposes the resulting read-only queries and collection list. reference stays within one collection, while all is the explicit cross-origin view. Body recovery, callability, and reference prior art are separate evidence dimensions, and none establishes the others.

call-sites and field-refs, in both CLI and MCP form, are static recovered-IL relationship evidence. They can prove that the indexed code references a target or field in the recovered body set; they do not prove runtime scene behavior, geometry behavior, lifecycle sequencing, or call order. Recovered native pseudocode is static evidence in the same sense: it requires runtime validation before being treated as behavioral fact.

Deep internals, including on-disk data layout, the pinned Cpp2IL definition, the validation policy, and build/environment identity, are documented in docs/REFERENCE.md.

Status

V1 shipped, and development continues on main. The environment can be discovered; builds can be fingerprinted, extracted, and indexed; symbols, source, relationships, and build diffs are queryable; S1API and S1MAPI are deep-indexed; the local web app, read-only MCP server, and agent skill all ship; and a failed scan never damages the last valid state.

Since V1, S1Atlas has added static call-site and field-reference queries, callable-surface queries, local reference-mod collections, behavior-ownership seam investigation, runtime-proof planning, and native-body recovery for stubbed IL2CPP methods. The CHANGELOG has the per-version detail.

Scene HTML is deferred for now; scene intelligence remains available through the CLI and MCP. Known issues and further work are tracked in Issues.

Contributing

Contributions welcome. See CONTRIBUTING.md. The one hard rule: never commit game content. S1Atlas distributes no game assets or decompiled output; all extracted and generated data stays local and gitignored.

License

MIT. Unofficial and not affiliated with the developers or publishers of Schedule I. See the disclaimer above.