Design Overgrowth And Surface Fuel Load

[Ustice]

Migrated from the file kanban board on 2026-05-23.

Original status: 08-deferred
Requires QA: false
Doc only: true
Agent level: Medium
Role: researcher
Dependencies: #14
Write scope: docs/DESIGN.md, docs/ARCHITECTURE.md, docs/TEST_PLAN.md

---

---

agent_level: Medium
role: researcher
requires_qa: false
doc_only: true
dependencies:

• Tune Fire Behavior With Recordings #14
  write_scope:
• docs/DESIGN.md
• docs/ARCHITECTURE.md
• docs/TEST_PLAN.md

---

Design Overgrowth And Surface Fuel Load

Goal

Define a later fuel-load mechanic for underbrush, grass, overgrown trees, or overgrown irrigated fields.

Why

The design notes that underbrush, grass, and overgrowth could become a future hazard: mature trees might burn relatively slowly while overgrown tiles burn fast. This should be designed intentionally instead of being smuggled into first-release material tuning.

Requirements

• Decide whether overgrowth is a new field, an entity state, a plant modifier, a terrain modifier, or a Timberborn adapter input.
• Preserve the simulator boundary: Timberborn may map overgrowth to fuel or flammability, but it must not own fire-spread rules.
• Define how overgrowth appears, grows, decays, is removed, and affects controlled burns.
• Define how irrigated fields, trees, and surface fuel differ.
• Decide what evidence would be needed before promoting the mechanic out of deferred scope.
• Update docs/DESIGN.md, docs/ARCHITECTURE.md, and docs/TEST_PLAN.md with the accepted future contract.

Dependencies

• Tune Fire Behavior With Recordings #14 provides fire behavior recording evidence that can inform fuel-load design.

Role

• Researcher.
• Follow researcher.md.

Verification

• Run git diff --check.
• No runtime validation is required for this design ticket.

Notes

• This is deferred future work.
• 2026-05-19 release scope correction: the broad overgrowth system remains deferred, but Add Rare Drought Aware Ignition Sources #35 promotes a focused release slice for rare deterministic ignition from fire-using buildings and dry dead vegetation during drought.
• Relevant design reference: docs/DESIGN.md section 20, "Ash And Fertility".