Inject LSP diagnostics as a synthetic user message after every successful
file edit (`edit_file`, `apply_patch`, `write_file`) so the agent sees
compile breaks before its next reasoning step. Largest agent-quality
lever in v0.7.0.
Pieces:
- `crates/tui/src/lsp/`: thin JSON-RPC stdio client (no `tower-lsp`),
per-language registry, diagnostics renderer producing the
`<diagnostics file="…">` block format. `LspManager` owns lazily
spawned per-language transports keyed by `Language`.
- `core/engine.rs`: hook on the success branch of the tool-result loop
derives the edited file path(s) per tool, queries the LspManager
with a 5 s timeout, and collects rendered blocks into
`pending_lsp_blocks`. The queue is flushed as a `text` content
block on the next request iteration so the model sees the
diagnostics before it streams its next turn.
- `[lsp]` config schema (`enabled`, `poll_after_edit_ms`,
`max_diagnostics_per_file`, `include_warnings`, optional
`servers` override) with built-in defaults for rust-analyzer,
gopls, pyright, typescript-language-server, and clangd.
- Failure modes are non-blocking by design: a missing LSP binary
logs a one-time warning and skips the hook; a crashed server or
poll timeout simply drops that turn's diagnostics. The agent's
work is never blocked.
Tests: 24 unit tests cover language detection, registry overrides,
filter/sort/truncate behavior, and the rendered block format. Three
engine-level tokio tests exercise the full path through a fake
transport (no real LSP server is ever spawned in CI).
Acceptance criteria (per #136):
- Edit introducing a type error -> next request body contains
`<diagnostics file="…">` block at the right line/col.
- `[lsp] enabled = false` -> no diagnostics injected.
- Snapshot test exercises full path with mock transport.
- LSP binary not on PATH -> one-time warning, agent proceeds.
- 5 s timeout, errors-only by default.
- Transports spawn lazily on first edit per language.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Hunter Bown
05a1032e00