chore(nim-bindings): replace dynlib dlopen with plain importc

[osmaczko]

The dynlib pragma hard-coded a library path and resolved it via dlopen() at runtime, preventing static linking and forcing a specific load-time path. Using bare {.importc.} lets consumers choose: link liblibchat dynamically at link time (--passL:-llibchat) or link it statically into their binary.

[Copilot]

Pull request overview

This PR updates the Nim FFI bindings to stop using Nim’s dynlib runtime loading/path resolution and instead rely on plain {.importc.} so consumers can choose dynamic or static linking at link time.

Changes:

• Removed compile-time/runtime library path resolution logic (previous CONVERSATIONS_LIB/relative target/{release,debug} discovery).
• Updated all exported FFI procs to use {.importc.} without dynlib:.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

With dynlib: removed, these FFI procs now require link-time configuration (e.g., --passL:-L... --passL:-llibchat or static .a) to resolve symbols. Please add/update package-level documentation (and any repo examples/build tasks) to ensure consumers (and nimble pingpong) know how to link against the Rust-built target/release artifacts; otherwise builds will fail with unresolved symbols.

Suggested change

	# Nim FFI bindings for libchat conversations library
	# Nim FFI bindings for libchat conversations library
	#
	# Linking / build notes
	# ----------------------
	# These procs are declared with `{.importc.}` and *no* `dynlib` pragma, so the
	# Nim compiler expects all symbols to be resolved by the linker at build time.
	# You must build the Rust library and tell Nim how to link against it.
	#
	# 1. Build the Rust library
	# From the Rust crate that defines the FFI (e.g. `libchat`), run:
	#
	# cargo build --release
	#
	# This will typically produce artifacts under:
	# target/release/libchat.a (static library)
	# target/release/libchat.so (Linux, shared library)
	# target/release/libchat.dylib (macOS, shared library)
	# target/release/chat.dll (Windows, shared library)
	#
	# 2. Tell Nim how to link
	# Use `--passL` to add the Rust `target/release` directory to the linker
	# search path, and link the `chat` library:
	#
	# nim c \
	# --passL:-L/path/to/rust-crate/target/release \
	# --passL:-lchat \
	# src/your_app.nim
	#
	# Adjust the `-L` path to point at your Rust crate's `target/release`
	# directory. The `-lchat` part must match the library name produced by
	# Rust (`libchat.*` -> `-lchat`).
	#
	# 3. Using Nimble (including `nimble pingpong`)
	# To ensure `nimble build`, `nimble test`, and `nimble pingpong` all link
	# correctly without extra command-line flags, add the linker switches to
	# your `.nimble` file, for example:
	#
	# # in yourpkg.nimble
	# switch("passL", "-Lpath/to/rust-crate/target/release")
	# switch("passL", "-lchat")
	#
	# If your layout is different (e.g. this Nim package lives inside the Rust
	# repo), you can use a relative path instead:
	#
	# switch("passL", "-L./target/release")
	# switch("passL", "-lchat")
	#
	# Without these link-time settings, builds that use the procs below will fail
	# with unresolved symbol / linker errors, even though the Nim code compiles.

[jazzz]

This change breaks nimble build for nim-bindings/conversation_example.nimble

CC: std/objectdollar.nim
CC: system/dollars.nim
CC: system.nim
CC: options.nim
CC: results.nim
CC: bindings.nim
CC: libchat.nim
CC: pingpong.nim
Hint:  [Link]
Undefined symbols for architecture arm64:
  "_create_context", referenced from:
      _newConversationsContext__OOZsrcZlibchat_u11 in @plibchat.nim.c.o
  "_create_intro_bundle", referenced from:
      _createIntroductionBundle__OOZsrcZlibchat_u44 in @plibchat.nim.c.o
  "_create_new_private_convo", referenced from:
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
  "_destroy_convo_result", referenced from:
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
  "_destroy_intro_result", referenced from:
      _createIntroductionBundle__OOZsrcZlibchat_u44 in @plibchat.nim.c.o
  "_handle_payload", referenced from:
      _handlePayload__OOZsrcZlibchat_u882 in @plibchat.nim.c.o
ld: symbol(s) not found for architecture arm64

[osmaczko]

This change breaks nimble build for nim-bindings/conversation_example.nimble

CC: std/objectdollar.nim
CC: system/dollars.nim
CC: system.nim
CC: options.nim
CC: results.nim
CC: bindings.nim
CC: libchat.nim
CC: pingpong.nim
Hint:  [Link]
Undefined symbols for architecture arm64:
  "_create_context", referenced from:
      _newConversationsContext__OOZsrcZlibchat_u11 in @plibchat.nim.c.o
  "_create_intro_bundle", referenced from:
      _createIntroductionBundle__OOZsrcZlibchat_u44 in @plibchat.nim.c.o
  "_create_new_private_convo", referenced from:
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
  "_destroy_convo_result", referenced from:
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
      _createNewPrivateConvo__OOZsrcZlibchat_u118 in @plibchat.nim.c.o
  "_destroy_intro_result", referenced from:
      _createIntroductionBundle__OOZsrcZlibchat_u44 in @plibchat.nim.c.o
  "_handle_payload", referenced from:
      _handlePayload__OOZsrcZlibchat_u882 in @plibchat.nim.c.o
ld: symbol(s) not found for architecture arm64

I believe I fixed, there is a segfault though.

[jazzz]

After digging seems like there are larger issues: #62

Its presented as a PR to this PR

[jazzz]

Test Passing, Nim bindings are linking. Looks good now.

[osmaczko]

@jazzz please take a look at the latest commit.

[jazzz]

🚀