feat(patch): added compact hashline diff preview for patch responses

- Added buildCompactHashlineDiffPreview() function to generate collapsed diff previews for tool responses. - Enhanced EditTool response to include diff summary with added/removed line counts and compact preview. - Added project-level discovery for .agent/ and .agents/ directories walking up to repository root. - Implemented helper functions for truncating long diff runs (collapseFromStart, collapseFromEnd, collapseFromMiddle).
2026-03-04 22:39:39 +01:00
parent f59b1b9fbf
commit 631021aa67
4 changed files with 174 additions and 3 deletions
@@ -710,3 +710,116 @@ export function applyHashlineEdits(
 		}
 	}
 }
+
+export interface CompactHashlineDiffPreview {
+	preview: string;
+	addedLines: number;
+	removedLines: number;
+}
+
+export interface CompactHashlineDiffOptions {
+	maxUnchangedRun?: number;
+	maxAdditionRun?: number;
+	maxDeletionRun?: number;
+	maxOutputLines?: number;
+}
+
+const NUMBERED_DIFF_LINE_RE = /^([ +-])(\d+)\|(.*)$/;
+
+type DiffRunKind = " " | "+" | "-" | "meta";
+type DiffRun = { kind: DiffRunKind; lines: string[] };
+
+function collapseFromStart(lines: string[], maxLines: number, label: string): string[] {
+	if (lines.length <= maxLines) return lines;
+	const hidden = lines.length - maxLines;
+	return [...lines.slice(0, maxLines), ` ... ${hidden} more ${label} lines`];
+}
+
+function collapseFromEnd(lines: string[], maxLines: number, label: string): string[] {
+	if (lines.length <= maxLines) return lines;
+	const hidden = lines.length - maxLines;
+	return [` ... ${hidden} more ${label} lines`, ...lines.slice(-maxLines)];
+}
+
+function collapseFromMiddle(lines: string[], maxLines: number, label: string): string[] {
+	if (lines.length <= maxLines * 2) return lines;
+	const hidden = lines.length - maxLines * 2;
+	return [...lines.slice(0, maxLines), ` ... ${hidden} more ${label} lines`, ...lines.slice(-maxLines)];
+}
+
+function splitDiffRuns(lines: string[]): DiffRun[] {
+	const runs: DiffRun[] = [];
+	for (const line of lines) {
+		const match = NUMBERED_DIFF_LINE_RE.exec(line);
+		const kind = (match?.[1] as " " | "+" | "-" | undefined) ?? "meta";
+		const prev = runs[runs.length - 1];
+		if (prev && prev.kind === kind) {
+			prev.lines.push(line);
+			continue;
+		}
+		runs.push({ kind, lines: [line] });
+	}
+	return runs;
+}
+
+/**
+ * Build a compact diff preview suitable for model-visible tool responses.
+ *
+ * Collapses long unchanged runs and long consecutive additions/removals so the
+ * model sees the shape of edits without replaying full file content.
+ */
+export function buildCompactHashlineDiffPreview(
+	diff: string,
+	options: CompactHashlineDiffOptions = {},
+): CompactHashlineDiffPreview {
+	const maxUnchangedRun = options.maxUnchangedRun ?? 2;
+	const maxAdditionRun = options.maxAdditionRun ?? 2;
+	const maxDeletionRun = options.maxDeletionRun ?? 2;
+	const maxOutputLines = options.maxOutputLines ?? 16;
+
+	const inputLines = diff.length === 0 ? [] : diff.split("\n");
+	const runs = splitDiffRuns(inputLines);
+
+	const out: string[] = [];
+	let addedLines = 0;
+	let removedLines = 0;
+
+	for (let runIndex = 0; runIndex < runs.length; runIndex++) {
+		const run = runs[runIndex];
+		switch (run.kind) {
+			case "meta":
+				out.push(...run.lines);
+				break;
+			case "+":
+				addedLines += run.lines.length;
+				out.push(...collapseFromStart(run.lines, maxAdditionRun, "added"));
+				break;
+			case "-":
+				removedLines += run.lines.length;
+				out.push(...collapseFromStart(run.lines, maxDeletionRun, "removed"));
+				break;
+			case " ":
+				if (runIndex === 0) {
+					out.push(...collapseFromEnd(run.lines, maxUnchangedRun, "unchanged"));
+					break;
+				}
+				if (runIndex === runs.length - 1) {
+					out.push(...collapseFromStart(run.lines, maxUnchangedRun, "unchanged"));
+					break;
+				}
+				out.push(...collapseFromMiddle(run.lines, maxUnchangedRun, "unchanged"));
+				break;
+		}
+	}
+
+	if (out.length > maxOutputLines) {
+		const hidden = out.length - maxOutputLines;
+		return {
+			preview: [...out.slice(0, maxOutputLines), ` ... ${hidden} more preview lines`].join("\n"),
+			addedLines,
+			removedLines,
+		};
+	}
+
+	return { preview: out.join("\n"), addedLines, removedLines };
+}
@@ -34,7 +34,14 @@ import { enforcePlanModeWrite, resolvePlanPath } from "../tools/plan-mode-guard"
 import { applyPatch } from "./applicator";
 import { generateDiffString, generateUnifiedDiffString, replaceText } from "./diff";
 import { findMatch } from "./fuzzy";
-import { type Anchor, applyHashlineEdits, computeLineHash, type HashlineEdit, parseTag } from "./hashline";
+import {
+	type Anchor,
+	applyHashlineEdits,
+	buildCompactHashlineDiffPreview,
+	computeLineHash,
+	type HashlineEdit,
+	parseTag,
+} from "./hashline";
 import { detectLineEnding, normalizeToLF, restoreLineEndings, stripBom } from "./normalize";
 import { type EditToolDetails, getLspBatchRequest } from "./shared";
 // Internal imports
@@ -597,11 +604,15 @@ export class EditTool implements AgentTool<TInput> {
 				.get();

 			const resultText = move ? `Moved ${path} to ${move}` : `Updated ${path}`;
+			const preview = buildCompactHashlineDiffPreview(diffResult.diff);
+			const summaryLine = `Changes: +${preview.addedLines} -${preview.removedLines}${preview.preview ? "" : " (no textual diff preview)"}`;
+			const warningsBlock = result.warnings?.length ? `\n\nWarnings:\n${result.warnings.join("\n")}` : "";
+			const previewBlock = preview.preview ? `\n\nDiff preview:\n${preview.preview}` : "";
 			return {
 				content: [
 					{
 						type: "text",
-						text: `${resultText}${result.warnings?.length ? `\n\nWarnings:\n${result.warnings.join("\n")}` : ""}`,
+						text: `${resultText}\n${summaryLine}${previewBlock}${warningsBlock}`,
 					},
 				],
 				details: {