DEV.md: cheat sheet for developers and LLMs.
What the developer wrote
Authored by Rusty Russell
DEV.md: cheat sheet for developers and LLMs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
What changed, and why it matters
This commit adds a new developer cheat-sheet file (DEV.md) with tips for building, testing, and contributing to Core Lightning. It contains only documentation and no code changes. There is no security issue.
No action required. This is a documentation-only commit with no security relevance.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The commit creates DEV.md with 15 lines of developer guidance covering build flags, test environment variables, generated files, contribution conventions, BOLT quote requirements, changelog tagging, deprecation practices, JSON-RPC design, pytest naming conventions, and tal helper semantics. No source code, build scripts, schemas, or configuration files were modified.
Changed components
DEV.md (new documentation only)Inspect captured patch +15 / −0
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+- Build with `--configure --enable-debugbuild` and `uv run make`. Much faster with `uv run make RUST=0`.
+- Env vars for tests: `RUST=0` (if RUST plugins were not built), `VALGRIND=0` (much faster), `TIMEOUT=10` to speed failures (or 100 if VALGRIND=1).
+- *gen.[ch] files are generated by the Makefile.
+- ccan/ is imported from ccan repo: PRs should go there, then `make update-ccan`.
+- Insert BOLT quotes (current version is checked out in .tmp.lightningrfc/) in source when dealing with protocol work, for `make check-source-bolt`. This ensures we keep up with spec changes. `...` means skip some, but not over a section boundary. `...` at the start means "continues directly from previous quote".
+- `make check-source` does formatting checks.
+- assert-based unit tests can "#include ../file.c", OR add objects to Makefile targets: `make update-mocks` will regenerate mocks for functions from link errors.
+- Commits should be reviewable, bisectable, and include tests. Pattern: one commit adds a python test with @pytest.mark.xfail(strict=True), next commit fixes the problem and removes that line.
+- Commits which fix crashes or bug MUST quote the bug for later searches: do not rely on being able to find the bug report in future!
+- Commits which create signficant user (not developer!) visible changes should have Changelog-(Added|Deprecated|Changed|Fixed|EXPERIMENTAL) for assembling CHANGELOG.md at release time.
+- Deprecations must use the deprecation infrastructure, and append to the table in doc/developers-guide/deprecated-features.md
+- Adding a new JSON-RPC command requires the most careful design: start with doc/schemas/NAME.json and add doc/NAME.json to MARKDOWNPAGES in doc/Makefile. `make doc-all` will regen the rest.
+- In pytest integration tests, name nodes l1, l2, etc in creation order. This matches the log prefixes they use (`lightningd-1` etc) and on test failure the logs and other ephemera will in /tmp/ltests-*/TESTNAME*/lightning-1/.
+- In pytest, never assert that a command raises an exception without specifying *exactly what* it raises! Use `with pytest.raises(RpcError, match='xxx'):`
+- tal_bytelen / tal_count of NULL are defined to be zero, and you may assume this.
Why this scored 15/100
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