refactor: reuse library discovery modules (Fixes #545) (#546)

Fixes #545. Isolates the mechanical module-reuse portion of #538.

- Use the public library discovery/locator modules from JSONRPC instead
of compiling duplicate binary module instances.
- Keep locator ordering, public APIs, state lifetimes, and orchestration
unchanged.
- Document that discovery/locator tests belong to the library target and
JSONRPC tests to the binary target.

Independent main-based branch; does not update #524 or #526 or modify
their changed files. No runtime speedup is claimed.

Validation: all 59 library/binary/JSONRPC integration tests pass on
Windows; Rust 1.98 formatting, mandatory Clippy, and
all-targets/all-features Clippy pass. Independent Reviewer returned no
findings. Platform CI and quality snapshots will validate the resulting
binary.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: karthiknadig

crates/pet/src/jsonrpc.rs

@@ -1,13 +1,13 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-use crate::find::find_and_report_envs;
-use crate::find::find_python_environments_in_workspace_folder_recursive;
-use crate::find::identify_python_executables_using_locators;
-use crate::find::SearchScope;
-use crate::locators::create_locators;
 use log::{error, info, trace, warn};
+use pet::find::find_and_report_envs;
+use pet::find::find_python_environments_in_workspace_folder_recursive;
+use pet::find::identify_python_executables_using_locators;
+use pet::find::SearchScope;
 use pet::initialize_tracing;
+use pet::locators::create_locators;
 use pet::resolve::resolve_environment;
 use pet_conda::Conda;
 use pet_conda::CondaLocator;

crates/pet/src/main.rs

@@ -8,9 +8,7 @@ use jsonrpc::start_jsonrpc_server;
 use pet::{find_and_report_envs_stdio, resolve_report_stdio, FindOptions};
 use pet_core::python_environment::PythonEnvironmentKind;
 
-mod find;
 mod jsonrpc;
-mod locators;
 
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]

docs/LOCATOR_STATE.md

@@ -50,3 +50,7 @@ When adding mutable state to a locator, classify it before relying on it across
 3. If later requests need refresh-discovered state, use `SyncedDiscoveryState`, implement `sync_refresh_state_from()`, and cover full, workspace, and kind-filtered scopes with tests.
 
 The locator graph has a regression test in `crates/pet/src/jsonrpc.rs` that pins the current classification of each locator created by `create_locators()`.
+
+## Module Ownership
+
+The CLI and JSONRPC server both use the `pet` library's public `find` and `locators` modules. The binary owns CLI dispatch and its `jsonrpc` adapter, rather than compiling separate copies of discovery and locator code. Discovery/locator unit tests run under the library target; JSONRPC orchestration tests remain under the binary target. This module boundary does not change the transient and shared locator lifetimes described above.