feat(ipuaro): add impact score to initial context

Add High Impact Files section to initial context showing which files
are most critical based on percentage of codebase that depends on them.

Changes:
- Add impactScore field to FileMeta (0-100)
- Add calculateImpactScore() helper function
- Update MetaAnalyzer to compute impact scores
- Add formatHighImpactFiles() to prompts.ts
- Add includeHighImpactFiles config option (default: true)
- 28 new tests (1826 total)

packages/ipuaro/src/domain/value-objects/FileMeta.ts

@@ -26,6 +26,8 @@ export interface FileMeta {
     isEntryPoint: boolean
     /** File type classification */
     fileType: "source" | "test" | "config" | "types" | "unknown"
+    /** Impact score (0-100): percentage of codebase that depends on this file */
+    impactScore: number
 }
 
 export function createFileMeta(partial: Partial<FileMeta> = {}): FileMeta {
@@ -41,6 +43,7 @@ export function createFileMeta(partial: Partial<FileMeta> = {}): FileMeta {
         isHub: false,
         isEntryPoint: false,
         fileType: "unknown",
+        impactScore: 0,
         ...partial,
     }
 }
@@ -48,3 +51,20 @@ export function createFileMeta(partial: Partial<FileMeta> = {}): FileMeta {
 export function isHubFile(dependentCount: number): boolean {
     return dependentCount > 5
 }
+
+/**
+ * Calculate impact score based on number of dependents and total files.
+ * Impact score represents what percentage of the codebase depends on this file.
+ * @param dependentCount - Number of files that depend on this file
+ * @param totalFiles - Total number of files in the project
+ * @returns Impact score from 0 to 100
+ */
+export function calculateImpactScore(dependentCount: number, totalFiles: number): number {
+    if (totalFiles <= 1) {
+        return 0
+    }
+    // Exclude the file itself from the total
+    const maxPossibleDependents = totalFiles - 1
+    const score = (dependentCount / maxPossibleDependents) * 100
+    return Math.round(Math.min(100, score))
+}

packages/ipuaro/src/infrastructure/indexer/MetaAnalyzer.ts

@@ -1,5 +1,6 @@
 import * as path from "node:path"
 import {
+    calculateImpactScore,
     type ComplexityMetrics,
     createFileMeta,
     type FileMeta,
@@ -430,6 +431,7 @@ export class MetaAnalyzer {
 
     /**
      * Batch analyze multiple files.
+     * Computes impact scores after all files are analyzed.
      */
     analyzeAll(files: Map<string, { ast: FileAST; content: string }>): Map<string, FileMeta> {
         const allASTs = new Map<string, FileAST>()
@@ -443,6 +445,12 @@ export class MetaAnalyzer {
             results.set(filePath, meta)
         }
 
+        // Compute impact scores now that we know total file count
+        const totalFiles = results.size
+        for (const [, meta] of results) {
+            meta.impactScore = calculateImpactScore(meta.dependents.length, totalFiles)
+        }
+
         return results
     }
 }

packages/ipuaro/src/infrastructure/llm/prompts.ts

@@ -18,6 +18,7 @@ export interface BuildContextOptions {
     includeSignatures?: boolean
     includeDepsGraph?: boolean
     includeCircularDeps?: boolean
+    includeHighImpactFiles?: boolean
     circularDeps?: string[][]
 }
 
@@ -132,6 +133,7 @@ export function buildInitialContext(
     const includeSignatures = options?.includeSignatures ?? true
     const includeDepsGraph = options?.includeDepsGraph ?? true
     const includeCircularDeps = options?.includeCircularDeps ?? true
+    const includeHighImpactFiles = options?.includeHighImpactFiles ?? true
 
     sections.push(formatProjectHeader(structure))
     sections.push(formatDirectoryTree(structure))
@@ -144,6 +146,13 @@ export function buildInitialContext(
         }
     }
 
+    if (includeHighImpactFiles && metas && metas.size > 0) {
+        const highImpactSection = formatHighImpactFiles(metas)
+        if (highImpactSection) {
+            sections.push(highImpactSection)
+        }
+    }
+
     if (includeCircularDeps && options?.circularDeps && options.circularDeps.length > 0) {
         const circularDepsSection = formatCircularDeps(options.circularDeps)
         if (circularDepsSection) {
@@ -568,6 +577,74 @@ export function formatCircularDeps(cycles: string[][]): string | null {
     return lines.join("\n")
 }
 
+/**
+ * Format high impact files table for display in context.
+ * Shows files with highest impact scores (most dependents).
+ *
+ * Format:
+ * ## High Impact Files
+ * | File | Impact | Dependents |
+ * |------|--------|------------|
+ * | src/utils/validation.ts | 67% | 12 files |
+ *
+ * @param metas - Map of file paths to their metadata
+ * @param limit - Maximum number of files to show (default: 10)
+ * @param minImpact - Minimum impact score to include (default: 5)
+ */
+export function formatHighImpactFiles(
+    metas: Map<string, FileMeta>,
+    limit = 10,
+    minImpact = 5,
+): string | null {
+    if (metas.size === 0) {
+        return null
+    }
+
+    // Collect files with impact score >= minImpact
+    const impactFiles: { path: string; impact: number; dependents: number }[] = []
+
+    for (const [path, meta] of metas) {
+        if (meta.impactScore >= minImpact) {
+            impactFiles.push({
+                path,
+                impact: meta.impactScore,
+                dependents: meta.dependents.length,
+            })
+        }
+    }
+
+    if (impactFiles.length === 0) {
+        return null
+    }
+
+    // Sort by impact score descending, then by path
+    impactFiles.sort((a, b) => {
+        if (a.impact !== b.impact) {
+            return b.impact - a.impact
+        }
+        return a.path.localeCompare(b.path)
+    })
+
+    // Take top N files
+    const topFiles = impactFiles.slice(0, limit)
+
+    const lines: string[] = [
+        "## High Impact Files",
+        "",
+        "| File | Impact | Dependents |",
+        "|------|--------|------------|",
+    ]
+
+    for (const file of topFiles) {
+        const shortPath = shortenPath(file.path)
+        const impact = `${String(file.impact)}%`
+        const dependents = file.dependents === 1 ? "1 file" : `${String(file.dependents)} files`
+        lines.push(`| ${shortPath} | ${impact} | ${dependents} |`)
+    }
+
+    return lines.join("\n")
+}
+
 /**
  * Format line range for display.
  */

packages/ipuaro/src/shared/constants/config.ts

@@ -117,6 +117,7 @@ export const ContextConfigSchema = z.object({
     includeSignatures: z.boolean().default(true),
     includeDepsGraph: z.boolean().default(true),
     includeCircularDeps: z.boolean().default(true),
+    includeHighImpactFiles: z.boolean().default(true),
 })
 
 /**