Manis Lib Generated Chunk Index

A lightweight library mod that maintains an index of generated Factorio chunks per surface, designed for other mods to query via a remote interface.

This mod has no gameplay content and no UI.

What this mod does

✅ Maintains a generated-chunk index

For each surface, the mod tracks generated chunks using:

• chunk key format: "cx:cy"
• set representation: chunk_key -> true
• array representation: array<string> for sampling and iteration

A “generated chunk” means:

• surface.is_chunk_generated({cx, cy}) == true

✅ Works for both new and existing saves

• Tracks new generation via:
• on_chunk_generated

• on_chunk_deleted

• Handles existing saves by enumerating:

• surface.get_chunks()
• validating with surface.is_chunk_generated(pos)

✅ Exposes a read-only remote interface

Interface name:

manis_generated_chunk_index

Remote Interface API

All functions take surface_index as the first argument.

1) is_ready(surface_index) -> boolean

Returns whether the index is ready for the given surface.

2) get_surface_status(surface_index) -> table|nil

Returns status information for the surface.

Possible fields:

• ready (boolean)
• scanning (boolean)
• count (integer)
• bounds (table|nil)
• bounds_dirty (boolean)
• surface_name (string|nil)

May return nil if the surface is unknown.

3) get_generated_chunk_keys(surface_index) -> array<string>

Primary API for callers.

Returns an array of chunk keys in "cx:cy" format.

Intended for:

• uniform sampling
• iteration
• derived structure building

4) has_chunk(surface_index, cx, cy) -> boolean

Returns whether the specific chunk exists in the index.

Intended for:

• point membership queries
• validation loops
• adjacency checks

5) get_generated_chunk_set(surface_index) -> table|nil

Returns the internal set representation:

• chunk_key -> true

Intended for:

• debugging
• special or advanced use cases

Caller must treat the returned table as read-only.

6) get_bounds(surface_index) -> table|nil

Returns best-effort bounds:

{ min_cx, max_cx, min_cy, max_cy }

Provided as a convenience.

Caller must not treat bounds as authoritative truth.

Recommended Call Patterns

Pattern A — Gate heavy logic with is_ready

Use when your mod depends on a complete index.

```lua
local iface = "manis_generated_chunk_index"
if not (remote.interfaces and remote.interfaces[iface]) then return end

local surface_index = game.surfaces["nauvis"].index
if not remote.call(iface, "is_ready", surface_index) then
return
end

-- safe to use index

Pattern B — Prefer has_chunk for point checks

If you only need a few coordinates, avoid pulling full data.

if remote.call(iface, "has_chunk", surface_index, cx, cy) then
-- generated
end

Pattern C — Use get_generated_chunk_keys for sampling

If you need random generated chunks:

local keys = remote.call(iface, "get_generated_chunk_keys", surface_index)
if keys and #keys > 0 then
local key = keys[math.random(#keys)]
end

Pattern D — Avoid frequent full-set pulls

get_generated_chunk_set(surface_index) may return a large table.

Best practice:

• Call it rarely
• Do not call every tick
• Convert to your own compact structure if needed

Data Guarantees

• The mod maintains an index of generated chunks per surface.
• The remote interface is read-only.
• Chunk keys are stable in "cx:cy" string format.

Non-Guarantees

• Ordering of chunks is not guaranteed.
• Bounds are best-effort derived data.
• No per-tick change stream is provided.

Compatibility

• Library mod (no entities, no UI).
• Designed for Factorio 2.0 runtime.
• Caller mods must treat returned data as read-only.