LSP Phase 6: edit-tool diagnostic integration

src/lsp/diagnostic.rs (new)
- pretty(diagnostic): one-line 'SEVERITY [line:col] msg' rendering with
  LSP 0-based → display 1-based coordinate conversion.
- report(file, issues): wraps in <diagnostics file="..."> block.
  ERROR severity only (warnings/hints are noise). MAX_PER_FILE=20 with
  '... and N more' overflow footer.
- build_report_block(current, all): the full agent-facing block that
  write/edit tools append. Two sections (each optional): current file
  errors, then up to MAX_PROJECT_DIAGNOSTICS_FILES=5 other-file errors
  (e.g. downstream callers that now fail type-checking).
- 15 tests covering: severity labels, 1-based coordinate display,
  missing-severity defaults to ERROR (regression — pretty must never
  panic or hide a diagnostic), error filtering (regression — warnings
  must NOT appear), wrap tags, cap at MAX_PER_FILE with overflow
  (regression — generated files with hundreds of errors must not blow
  context), other-files cap (regression — single edit shouldn't dump
  entire project state), warning-only files don't appear, caller path
  preserved in display (regression — not canonical form).

src/agent/tools/write.rs
- New optional Option<Arc<LspManager>> field. With manager set, after
  the write: touch_file(AwaitPush) + build_report_block + append to
  output. DIAGNOSTIC_WAIT = 10s matches opencode.
- Shared append_lsp_block helper used by both write and edit.
- 2 tests: no-manager path preserves pre-LSP output exactly
  (regression); manager-with-no-diagnostics appends nothing.

src/agent/tools/edit.rs
- Same Option<Arc<LspManager>> field + integration. Diagnostic block
  appended after the existing diff block.

src/agent/tools/read.rs
- New optional Option<Arc<LspManager>> field. Read warms the LSP server
  with a fire-and-forget tokio::spawn(touch_file(Notify)). The read's
  primary output is unchanged — no diagnostic block (that's the edit
  tool's job).

src/agent/builder.rs
- All three tool constructors now pass None for lsp_manager. Phase 7's
  CLI/config plumbing will populate it.

Code review fixes applied before push:
- Display caller path (not canonical form) in current-file section so
  macOS /tmp / /private/tmp asymmetry doesn't confuse the agent.

Phase 5: 100, Phase 6: +16 -> 116 LSP tests. Suite: 405 -> 421.

Author: Yogthos

src/agent/builder.rs

@@ -140,18 +140,22 @@ pub async fn build_agent_inner<M: CompletionModel + 'static>(
                 permission.clone(),
                 ask_tx.clone(),
                 cache.clone(),
+                // Phase 7 will populate this from build_channels.
+                None,
             )),
             Box::new(tools::WriteTool::with_cache(
                 permission.clone(),
                 ask_tx.clone(),
                 plan_file.clone(),
                 cache.clone(),
+                None,
             )),
             Box::new(tools::EditTool::with_cache(
                 permission.clone(),
                 ask_tx.clone(),
                 plan_file.clone(),
                 cache.clone(),
+                None,
             )),
             Box::new(tools::BashTool::with_cache(
                 permission.clone(),

src/agent/tools/edit.rs

@@ -1,16 +1,22 @@
 use std::path::PathBuf;
+use std::sync::Arc;
 
 use rig::completion::ToolDefinition;
 use rig::tool::Tool;
 
 use crate::agent::tools::cache::ToolCache;
 use crate::agent::tools::{AskSender, EditArgs, PermCheck, ToolError, check_perm_path};
+use crate::lsp::manager::LspManager;
 
 pub struct EditTool {
     pub permission: Option<PermCheck>,
     pub ask_tx: Option<AskSender>,
     plan_file: Option<PathBuf>,
     cache: Option<ToolCache>,
+    /// When set, the tool touches the edited file on the LSP server and
+    /// appends any diagnostic block to its output. `None` reproduces the
+    /// pre-LSP behaviour.
+    lsp_manager: Option<Arc<LspManager>>,
 }
 
 impl EditTool {
@@ -25,6 +31,7 @@ impl EditTool {
             ask_tx,
             plan_file,
             cache: None,
+            lsp_manager: None,
         }
     }
 
@@ -33,12 +40,14 @@ impl EditTool {
         ask_tx: Option<AskSender>,
         plan_file: Option<PathBuf>,
         cache: ToolCache,
+        lsp_manager: Option<Arc<LspManager>>,
     ) -> Self {
         EditTool {
             permission,
             ask_tx,
             plan_file,
             cache: Some(cache),
+            lsp_manager,
         }
     }
 
@@ -203,6 +212,7 @@ impl Tool for EditTool {
             new_content
         };
 
+        let write_at = std::time::Instant::now();
         tokio::fs::write(&args.path, &output).await?;
         // File mutated → invalidate cached reads/greps/listings for this turn.
         if let Some(ref cache) = self.cache {
@@ -225,6 +235,16 @@ impl Tool for EditTool {
                 &args.new_text,
             ));
         }
+
+        let path = std::path::Path::new(&args.path);
+        result.push_str(
+            &crate::agent::tools::write::append_lsp_block(
+                self.lsp_manager.as_ref(),
+                path,
+                write_at,
+            )
+            .await,
+        );
         Ok(result)
     }
 }

src/agent/tools/mod.rs

@@ -20,7 +20,7 @@ mod task_status;
 mod todo;
 mod webfetch;
 mod websearch;
-mod write;
+pub(crate) mod write;
 
 pub use apply_patch::ApplyPatchTool;
 pub use bash::BashTool;

src/agent/tools/read.rs

@@ -1,13 +1,20 @@
+use std::sync::Arc;
+
 use rig::completion::ToolDefinition;
 use rig::tool::Tool;
 
 use crate::agent::tools::cache::ToolCache;
 use crate::agent::tools::{AskSender, PermCheck, ReadArgs, ToolError, check_perm_path};
+use crate::lsp::manager::{LspManager, TouchMode};
 
 pub struct ReadTool {
     pub permission: Option<PermCheck>,
     pub ask_tx: Option<AskSender>,
     pub cache: Option<ToolCache>,
+    /// When set, the tool fires off a `touch_file` to warm the LSP server
+    /// so subsequent edits surface diagnostics quickly. Fire-and-forget:
+    /// the read tool does not wait or surface diagnostics in its output.
+    pub lsp_manager: Option<Arc<LspManager>>,
 }
 
 impl ReadTool {
@@ -17,18 +24,21 @@ impl ReadTool {
             permission,
             ask_tx,
             cache: None,
+            lsp_manager: None,
         }
     }
 
     pub fn with_cache(
         permission: Option<PermCheck>,
         ask_tx: Option<AskSender>,
         cache: ToolCache,
+        lsp_manager: Option<Arc<LspManager>>,
     ) -> Self {
         ReadTool {
             permission,
             ask_tx,
             cache: Some(cache),
+            lsp_manager,
         }
     }
 }
@@ -109,6 +119,16 @@ impl Tool for ReadTool {
             cache.set(&cache_key, info.clone());
         }
 
+        // Fire-and-forget LSP warmup so the server already has the file
+        // open by the time the agent edits it (and we can wait_for_push
+        // quickly). No diagnostic surfacing on read.
+        if let Some(manager) = self.lsp_manager.clone() {
+            let path = std::path::PathBuf::from(&args.path);
+            tokio::spawn(async move {
+                manager.touch_file(&path, TouchMode::Notify).await;
+            });
+        }
+
         Ok(info)
     }
 }

src/agent/tools/write.rs

@@ -1,16 +1,29 @@
 use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::{Duration, Instant};
 
 use rig::completion::ToolDefinition;
 use rig::tool::Tool;
 
 use crate::agent::tools::cache::ToolCache;
 use crate::agent::tools::{AskSender, PermCheck, ToolError, WriteArgs, check_perm_path};
+use crate::lsp::diagnostic;
+use crate::lsp::manager::{LspManager, TouchMode};
+
+/// How long to wait for the LSP server to publish fresh diagnostics after
+/// a write. Matches opencode's `DIAGNOSTICS_FULL_WAIT_TIMEOUT_MS`. Bounded
+/// so a stuck server doesn't hold up the agent's turn.
+const DIAGNOSTIC_WAIT: Duration = Duration::from_secs(10);
 
 pub struct WriteTool {
     pub permission: Option<PermCheck>,
     pub ask_tx: Option<AskSender>,
     plan_file: Option<PathBuf>,
     cache: Option<ToolCache>,
+    /// When set, the tool touches the file on the LSP server after writing
+    /// and appends any resulting diagnostic block to its output. `None`
+    /// reproduces the pre-LSP behaviour exactly.
+    lsp_manager: Option<Arc<LspManager>>,
 }
 
 impl WriteTool {
@@ -25,6 +38,7 @@ impl WriteTool {
             ask_tx,
             plan_file,
             cache: None,
+            lsp_manager: None,
         }
     }
 
@@ -33,12 +47,14 @@ impl WriteTool {
         ask_tx: Option<AskSender>,
         plan_file: Option<PathBuf>,
         cache: ToolCache,
+        lsp_manager: Option<Arc<LspManager>>,
     ) -> Self {
         WriteTool {
             permission,
             ask_tx,
             plan_file,
             cache: Some(cache),
+            lsp_manager,
         }
     }
 }
@@ -90,11 +106,114 @@ impl Tool for WriteTool {
             tokio::fs::create_dir_all(parent).await?;
         }
         let bytes = args.content.len();
+        let write_at = Instant::now();
         tokio::fs::write(path, &args.content).await?;
         // File mutated → invalidate cached reads/greps/listings for this turn.
         if let Some(ref cache) = self.cache {
             cache.clear();
         }
-        Ok(format!("Written {} bytes to {}", bytes, args.path))
+
+        let mut output = format!("Written {} bytes to {}", bytes, args.path);
+        output.push_str(&append_lsp_block(self.lsp_manager.as_ref(), path, write_at).await);
+        Ok(output)
+    }
+}
+
+/// Run `touch_file` + diagnostic-report assembly. Returns the appendable
+/// block (empty string when there's nothing to surface or no manager).
+/// Errors during touch/wait are intentionally swallowed — diagnostic
+/// surfacing is a side-effect; the write tool's primary contract is
+/// "wrote the file".
+pub(crate) async fn append_lsp_block(
+    manager: Option<&Arc<LspManager>>,
+    path: &Path,
+    after: Instant,
+) -> String {
+    let Some(manager) = manager else {
+        return String::new();
+    };
+    manager
+        .touch_file(
+            path,
+            TouchMode::AwaitPush {
+                after,
+                timeout: DIAGNOSTIC_WAIT,
+            },
+        )
+        .await;
+    let diagnostics = manager.all_diagnostics();
+    diagnostic::build_report_block(path, &diagnostics)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::agent::tools::cache::ToolCache;
+    use crate::lsp::manager::LspManager;
+    use crate::lsp::spawn::{Spawned, Spawner};
+    use futures::future::BoxFuture;
+
+    fn tempfile_in(dir: &Path, name: &str) -> PathBuf {
+        dir.join(name)
+    }
+
+    /// Synthetic spawner — never actually invoked because the write paths
+    /// we test don't have an extension the manager would claim.
+    struct NopSpawner;
+    impl Spawner for NopSpawner {
+        fn spawn<'a>(
+            &'a self,
+            _server_id: &'a str,
+            _root: &'a Path,
+        ) -> BoxFuture<'a, std::io::Result<Spawned>> {
+            Box::pin(async { Err(std::io::Error::other("not used")) })
+        }
+    }
+
+    // Regression: when no LSP manager is provided, the tool's output must
+    // be exactly what it was pre-LSP (just "Written N bytes to PATH").
+    // The diagnostic-append code path must not perturb the no-manager case.
+    #[tokio::test]
+    async fn regression_no_manager_preserves_existing_output() {
+        let dir = std::env::temp_dir().join(format!("dirge-write-no-mgr-{}", std::process::id()));
+        let _ = std::fs::create_dir_all(&dir);
+        let path = tempfile_in(&dir, "no-mgr.txt");
+
+        let tool = WriteTool::with_cache(None, None, None, ToolCache::new(), None);
+        let out = tool
+            .call(WriteArgs {
+                path: path.to_string_lossy().into_owned(),
+                content: "hello".into(),
+            })
+            .await
+            .unwrap();
+        assert!(out.starts_with("Written 5 bytes"), "got: {out}");
+        // No diagnostic block since manager is None.
+        assert!(!out.contains("LSP errors"));
+        std::fs::remove_dir_all(&dir).ok();
+    }
+
+    // When a manager IS provided but has no diagnostics (mock spawner that
+    // never gets called for the extension), the tool's output still starts
+    // with the write confirmation and contains no diagnostic block.
+    #[tokio::test]
+    async fn manager_with_no_diagnostics_appends_nothing() {
+        let dir = std::env::temp_dir().join(format!("dirge-write-with-mgr-{}", std::process::id()));
+        let _ = std::fs::create_dir_all(&dir);
+        let path = tempfile_in(&dir, "with-mgr.unknown_ext");
+
+        let manager = Arc::new(LspManager::new(Arc::new(NopSpawner), dir.clone()));
+        let tool = WriteTool::with_cache(None, None, None, ToolCache::new(), Some(manager));
+
+        let out = tool
+            .call(WriteArgs {
+                path: path.to_string_lossy().into_owned(),
+                content: "hi".into(),
+            })
+            .await
+            .unwrap();
+        assert!(out.starts_with("Written 2 bytes"));
+        assert!(!out.contains("LSP errors"), "got: {out}");
+        std::fs::remove_dir_all(&dir).ok();
     }
 }