Solo-C: a tiny coding agent in a single C file

main.c is the whole agent: a readline REPL that talks to any OpenAI-compatible
/chat/completions endpoint and exposes exactly one tool, bash(command). Commands
run through the user's shell with stdout and stderr merged, a hard timeout, and
a process-group kill; the output and an exit marker go back to the model until
it answers without calling a tool.

make static-deps builds curl and c-ares from source into static-deps/, so
`make static` can link a fully static binary on distros that get in the way: the
distro libcurl.a drags in libpsl, brotli, zstd and nghttp2, whose static objects
are GCC 14 LTO bytecode a newer linker cannot read, and a minimal system often
ships no libcares.a at all.

Two details worth keeping in mind when editing mkstaticdeps.sh. curl 8.22 takes
--enable-ares=PREFIX rather than the older --with-cares, and it only warns
about options it does not recognise, so the wrong spelling turns off async DNS
in silence instead of failing. And link order is load-bearing: libcares.a has
to come after libcurl.a or ares_* stays undefined.

.gitignore

@@ -0,0 +1,75 @@
+# Build artifacts.
+# Both names are produced by the Makefile targets `solo` and `static`.
+# Anchor on the root so a directory called solo is still tracked.
+/solo
+/solo-static
+*.o
+*.a
+*.so
+*.so.*
+
+# Prebuilt libcurl.a for `make static`, regenerated by `make static-deps`
+# (see mkstaticdeps.sh). Large, and tied to the machine that built it.
+/static-deps/
+/curl-*/
+
+# Per-directory session state: the live model parameters, the tool schema and
+# the full conversation transcript, which can contain secrets. Runtime data, so
+# it must never be committed.
+.solo_sess.json
+*.solo_sess.json
+
+# Readline history, in case HOME or XDG is pointed here in some setups.
+.solo_history
+.history
+
+# Scratch space the agent is told to use.
+/solo-tmp/
+/tmp/
+
+# Editor and tooling droppings.
+*~
+*.bak
+*.orig
+*.rej
+*.swp
+*.swo
+.*.sw?
+.\#*
+\#*\#
+
+# Vim.
+.vim/
+*.vim
+*.swo
+
+# Emacs.
+*.elc
+*.symc
+.\#*
+\#*\#
+
+# Compiled binaries and debug output from ad-hoc experiments.
+/core
+/core.*
+vgcore.*
+a.out
+gdb.core
+
+# Coverage and profiling, if instrumentation is ever added.
+*.gcda
+*.gcno
+*.gcov
+*.profraw
+*.profdata
+
+# OS cruft.
+.DS_Store
+Thumbs.db
+desktop.ini
+
+# Secrets and local overrides. Commit a .env.example instead.
+.env
+.env.local
+SOLO_API_KEY
+SOLO_SYSPROMPT.local