refactor: remove Python implementation, promote Rust to repo root

[RohanAwhad]

Summary

• Remove entire Python implementation (source, tests, packaging, Docker build)
• Move Rust code from rust/ subdirectory to repo root (Cargo.toml, src/, tests/ at root)
• Update CI workflow to remove working-directory: rust from all jobs
• Update .gitignore, AGENTS.md, README.md for Rust-only repo; delete CLAUDE.md
• PRD at .dingllm/prds/v3/000_remove_python.md

Test plan

• cargo build from repo root
• cargo test -- --test-threads=1 — 154 tests pass
• cargo clippy -- -D warnings — clean
• cargo fmt -- --check — clean

Smoke test plan

• Happy path: cargo build && cargo test -- --test-threads=1 succeeds from repo root
• Edge case: No Python files remain in tracked tree
• Regression: All 154 existing Rust tests still pass after the move

Unit tests

cargo test -- --test-threads=1

running 12 tests  (src/main.rs)    — all ok
running 8 tests   (test_e2e.rs)    — all ok
running 12 tests  (test_output.rs) — all ok
running 57 tests  (test_providers.rs) — all ok
running 37 tests  (test_tools.rs)  — all ok
running 13 tests  (test_types_prompts.rs) — all ok
running 15 tests  (test_websearch.rs) — all ok

test result: ok. 154 passed; 0 failed; 0 ignored

[RohanAwhad]

Babysit PR — Status

Resolved review items

#	Finding	Commit	Status
1	AGENTS.md references deleted python_runtime_docker/	ddf7848	Resolved
2	README.md references deleted python_runtime_docker/	ddf7848	Resolved

Open items

#	Finding	Status
3	.dingllm/serve.py survives as tracked Python file	Acceptable — dev utility, not Python implementation

Details on #1 & #2

python_runtime_docker/ (Dockerfile, build_docker.sh, kernel_server.py) was deleted by this PR, but it is a runtime dependency of the Rust pythonexec tool (src/tools/pythonexec.rs:12 hardcodes buzz/python-exec:latest). The PRD erroneously listed it as Python implementation infrastructure.

Restored all 3 files from main branch. AGENTS.md:26 and README.md:137 references are now valid again.

Details on #3

.dingllm/serve.py is a lightweight dev doc server for browsing .dingllm/ docs locally — not part of the BuzzLLM Python implementation. PRD intent was to remove the Python BuzzLLM source/tests/packaging, not unrelated dev utilities. Acceptable as-is.

Additional commits

Commit	Description
ddf7848	Restore python_runtime_docker/ — Rust pythonexec tool dependency

CI Status

Waiting for CI on new SHA ddf7848.

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— Bazinga PR Babysitter

[RohanAwhad]

Code Review

Decision: ready_with_followups

Scope: Reviewed 2 unique commits out of 2 total. Target branch: main.

Intent & Optimality (pr-intent-review)

Understood intent: Remove the unmaintained Python implementation of BuzzLLM and promote the Rust implementation from the rust/ subdirectory to the repository root, making the repo a single-language Rust project. Update all supporting files (CI, docs, gitignore) to reflect the new layout.

Optimality: Optimal. Single atomic commit covering delete + move + doc updates is the right approach — avoids intermediate broken states. git mv for Rust files preserves blame/log history. All Rust source files are 100% similarity (pure renames, zero code changes). The change is PRD-driven (.dingllm/prds/v3/000_remove_python.md).

Breaking Changes (code-review-breaking-change)

No code-level breaking changes. CLI interface, API contracts, tool schemas, and provider interfaces are all byte-identical (R100 renames). Configuration is additive-only (.cargo/config.toml). CI is correctly updated.

python_runtime_docker/ was deleted — Resolved in ddf7848: directory restored with identical files. AGENTS.md and README.md references are now valid.

Change Size (code-review-change-size)

PASS. The raw diff is misleading — it consists of 32 pure renames (0 delta), ~6,400 lines of Python deletion (the stated purpose), and ~186 lines of authored additions (53 non-doc). Well under both the 500 and 800 thresholds. No scope creep. Splitting would create broken intermediate states for no reviewability gain.

Test Integrity (code-review-test-integrity)

No test integrity issues found. Python test deletions are justified (dead code — they import from the deleted src/buzzllm/ package). All 6 Rust test files are R100 renames with 124 #[test] functions preserved. CI preserves all 4 quality gates (build, test, clippy, fmt) at equal strictness.

Spec Compliance

• PRD: .dingllm/prds/v3/000_remove_python.md — minor gap (see finding 3)
• Diagrams: .dingllm/specs/v2/*.mmd — aligned (already reference Rust layout)

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Action Items

• 1. [MEDIUM] AGENTS.md references deleted python_runtime_docker/ directory — AGENTS.md:26

Details

Resolved in commit ddf7848 — python_runtime_docker/ directory restored with identical files (Dockerfile, build_docker.sh, kernel_server.py). AGENTS.md reference is now valid.

• 2. [MEDIUM] README.md references deleted python_runtime_docker/ directory — README.md:137

Details

Resolved in commit ddf7848 — same fix as finding 1. README.md reference is now valid.

• 3. [LOW] .dingllm/serve.py survives as a tracked Python file — .dingllm/serve.py

Details

PRD acceptance criterion 6 states "No Python files remain in tracked tree". However, .dingllm/serve.py (~280 lines, a lightweight dev doc server) is still tracked.

This file is a developer utility for browsing .dingllm/ docs locally — not part of the BuzzLLM Python implementation. The PRD's intent was to remove the Python BuzzLLM source/tests/packaging, not unrelated dev utilities.

Recommendation: Acceptable to leave as-is. Non-blocking follow-up.

Spec gap (PRD criterion wording vs. intent).

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— Reviewed by Coding Agent