AGENTS.md

1# SDP Runtime Assumptions — sdp-context-core v1
2 
3**Package**: `internal/context/` (package `sdpcontext`)
4**Contract**: v1.0.0
5**Module**: `sdp_dev`
6 
7## Context Objects
8 
9**Primary output**: `RepoMap` — complete repository structure for SDP runtime.
10**Secondary**: `DiffResult` — change-aware retrieval for incremental processing.
11 
12## Environment Requirements
13 
14- **Git**: required for `DiffRetriever` operations; binary must be in PATH
15- **File system**: POSIX-compatible access for `RepoMapper` traversal
16- **No network**: all operations are local-only
17 
18## Configuration
19 
20- **PromptBudget**: configurable per model (gpt-4, claude-opus, etc.)
21- **Cache hashing**: deterministic SHA-256; inputs sorted before hashing
22- **Layer injection**: order preserved; truncation removes oldest layers first
23 
24## Dependencies
25 
26**No internal SDP dependencies** — this is a leaf substrate package.
27Imports only: Go stdlib (`context`, `time`).
28 
29## Version Control
30 
31- **Current support**: git-only
32- **Git required**: `DiffRetriever` assumes git repository
33- **Future extensibility**: interface contract allows VCS-agnostic implementations
34 
35## File System Assumptions
36 
37- **POSIX paths**: `/` as separator; relative paths from repo root
38- **Stat access**: requires read access for file metadata (mtime, size)
39- **Symbolic links**: followed during repo mapping
40- **Binary files**: detected and skipped during line counting
41 
42## Token Budget Heuristics
43 
44- **Chars per token**: 4 (ASCII average)
45- **Context reservation**: 15-25% of total budget for runtime injection
46- **Layer ordering**: array order preserved during prompt construction
47