docs: expand repo/workflow guidance in agent instructions

Author: napetrov

.github/copilot-instructions.md

@@ -3,14 +3,18 @@
 ## Source of truth
 This file is canonical for Copilot behavior in this repository.
 
-`AGENTS.md` files provide directory scope/guardrails for AGENTS-aware tools and
-should not duplicate Copilot policy text.
+`AGENTS.md` files provide directory scope/guardrails for AGENTS-aware tools and should not duplicate Copilot policy text.
 
 ## Mandatory flow
 Read root `AGENTS.md`, then nearest local `AGENTS.md` for edited files; most specific wins.
 
+## Contribution expectations
+- Keep diffs minimal and scoped to the task.
+- Preserve API behavior by default.
+- For behavior/API changes: update tests, and docs/examples when user-visible.
+- For bug fixes: prefer adding regression coverage.
+
 ## Authoring rules
-- Keep suggestions minimal and scoped.
 - Use source-of-truth files for mutable details.
 - Do not invent or hardcode versions, flags, or matrix values.
 

AGENTS.md

@@ -2,18 +2,23 @@
 
 This file is for AGENTS-aware tools.
 
-Scope:
-- Repository context for AGENTS-aware agents.
-- Directory routing to local AGENTS files.
+## What this repository is
+`dpnp` is the Data Parallel Extension for NumPy: a NumPy-compatible Python API with accelerated execution backends and cross-platform packaging/CI.
 
-For Copilot policy (flow, source-of-truth, edit hygiene), see:
+## How to work in this repo
+- Keep changes small and single-purpose (bug fix, perf, docs, or infra).
+- Preserve API behavior by default; call out intentional behavior changes in PR text.
+- Pair user-visible changes with tests and docs/examples updates.
+- Avoid duplicating mutable details (versions/flags/matrix) in instruction docs.
+
+For Copilot behavior policy (flow, source-of-truth, edit hygiene), see:
 - `.github/copilot-instructions.md` (canonical for Copilot behavior)
 
-Directory map:
-- `.github/AGENTS.md`
-- `dpnp/AGENTS.md`
-- `doc/AGENTS.md`
-- `examples/AGENTS.md`
-- `benchmarks/AGENTS.md`
-- `scripts/AGENTS.md`
-- `tests_external/AGENTS.md`
+## Directory map
+- `.github/AGENTS.md` — CI/workflow/automation context
+- `dpnp/AGENTS.md` — core implementation behavior guardrails
+- `doc/AGENTS.md` — documentation updates and consistency
+- `examples/AGENTS.md` — runnable user-facing examples
+- `benchmarks/AGENTS.md` — reproducible performance evaluation
+- `scripts/AGENTS.md` — maintenance/developer scripts
+- `tests_external/AGENTS.md` — external/integration validation scope