Initial Commit

config.ts

@@ -0,0 +1,251 @@
+import * as fs from "node:fs"
+import * as path from "node:path"
+import * as os from "node:os"
+import { parse as parseJsonc } from "jsonc-parser"
+
+// ---------------------------------------------------------------------------
+// Types
+// ---------------------------------------------------------------------------
+
+export interface DcpConfig {
+  enabled: boolean
+  debug: boolean
+  manualMode: {
+    enabled: boolean
+    automaticStrategies: boolean // run dedup/purge even in manual mode
+  }
+  compress: {
+    maxContextPercent: number // 0-1, e.g. 0.8 — above this, aggressive nudges
+    minContextPercent: number // 0-1, e.g. 0.4 — below this, no nudges
+    nudgeFrequency: number // inject nudge every N context events (default: 5)
+    iterationNudgeThreshold: number // nudge after N tool calls since last user msg (default: 15)
+    nudgeForce: "strong" | "soft"
+    protectedTools: string[] // these tool outputs always protected from pruning
+    protectUserMessages: boolean
+  }
+  strategies: {
+    deduplication: {
+      enabled: boolean
+      protectedTools: string[]
+    }
+    purgeErrors: {
+      enabled: boolean
+      turns: number // prune error inputs after N user turns (default: 4)
+      protectedTools: string[]
+    }
+  }
+  protectedFilePatterns: string[]
+  pruneNotification: "off" | "minimal" | "detailed"
+}
+
+// ---------------------------------------------------------------------------
+// Defaults
+// ---------------------------------------------------------------------------
+
+const DEFAULT_CONFIG: DcpConfig = {
+  enabled: true,
+  debug: false,
+  manualMode: {
+    enabled: false,
+    automaticStrategies: true,
+  },
+  compress: {
+    maxContextPercent: 0.8,
+    minContextPercent: 0.4,
+    nudgeFrequency: 5,
+    iterationNudgeThreshold: 15,
+    nudgeForce: "soft",
+    protectedTools: ["compress", "write", "edit"],
+    protectUserMessages: false,
+  },
+  strategies: {
+    deduplication: {
+      enabled: true,
+      protectedTools: [],
+    },
+    purgeErrors: {
+      enabled: true,
+      turns: 4,
+      protectedTools: [],
+    },
+  },
+  protectedFilePatterns: [],
+  pruneNotification: "detailed",
+}
+
+const DEFAULT_CONFIG_FILE_CONTENT = `{
+  // Dynamic Context Pruning (DCP) configuration
+  // Full schema reference: https://github.com/your-org/pi-dynamic-context-pruning
+  //
+  // "$schema": "...",
+  //
+  // Uncomment and edit properties you want to override:
+  //
+  // "enabled": true,
+  // "debug": false,
+  // "manualMode": {
+  //   "enabled": false,
+  //   "automaticStrategies": true
+  // },
+  // "compress": {
+  //   "maxContextPercent": 0.8,
+  //   "minContextPercent": 0.4,
+  //   "nudgeFrequency": 5,
+  //   "iterationNudgeThreshold": 15,
+  //   "nudgeForce": "soft",
+  //   "protectedTools": ["compress", "write", "edit"],
+  //   "protectUserMessages": false
+  // },
+  // "strategies": {
+  //   "deduplication": { "enabled": true, "protectedTools": [] },
+  //   "purgeErrors": { "enabled": true, "turns": 4, "protectedTools": [] }
+  // },
+  // "protectedFilePatterns": [],
+  // "pruneNotification": "detailed"
+}
+`
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+/**
+ * Recursively merge `override` into `base`. Arrays are union-merged (deduped).
+ * Returns a new object; does not mutate inputs.
+ */
+function deepMerge<T>(base: T, override: Partial<T>): T {
+  if (override === null || override === undefined) return base
+  if (typeof base !== "object" || typeof override !== "object") {
+    return override as T
+  }
+
+  const result: Record<string, unknown> = { ...(base as Record<string, unknown>) }
+
+  for (const key of Object.keys(override as Record<string, unknown>)) {
+    const baseVal = (base as Record<string, unknown>)[key]
+    const overVal = (override as Record<string, unknown>)[key]
+
+    if (Array.isArray(baseVal) && Array.isArray(overVal)) {
+      // Union merge: combine and deduplicate by value
+      const combined = [...baseVal, ...overVal]
+      result[key] = [...new Set(combined)]
+    } else if (
+      overVal !== null &&
+      typeof overVal === "object" &&
+      !Array.isArray(overVal) &&
+      baseVal !== null &&
+      typeof baseVal === "object" &&
+      !Array.isArray(baseVal)
+    ) {
+      result[key] = deepMerge(
+        baseVal as Record<string, unknown>,
+        overVal as Record<string, unknown>,
+      )
+    } else if (overVal !== undefined) {
+      result[key] = overVal
+    }
+  }
+
+  return result as T
+}
+
+/**
+ * Parse a JSONC file and return a plain object.
+ * Returns `{}` on any error (missing file, parse error).
+ */
+function readJsoncFile(filePath: string): Record<string, unknown> {
+  let raw: string
+  try {
+    raw = fs.readFileSync(filePath, "utf8")
+  } catch {
+    return {}
+  }
+
+  const errors: unknown[] = []
+  const parsed = parseJsonc(raw, errors)
+  if (errors.length > 0) {
+    // Non-fatal: return whatever was parsed (jsonc-parser is lenient)
+  }
+  if (parsed === null || typeof parsed !== "object" || Array.isArray(parsed)) {
+    return {}
+  }
+  return parsed as Record<string, unknown>
+}
+
+/**
+ * Ensure the global config file exists, creating it with defaults if missing.
+ */
+function ensureGlobalConfig(filePath: string): void {
+  const dir = path.dirname(filePath)
+  try {
+    fs.mkdirSync(dir, { recursive: true })
+    if (!fs.existsSync(filePath)) {
+      fs.writeFileSync(filePath, DEFAULT_CONFIG_FILE_CONTENT, "utf8")
+    }
+  } catch {
+    // Best-effort; do not crash if we cannot write
+  }
+}
+
+/**
+ * Walk up from `startDir` looking for `.pi/dcp.jsonc`.
+ * Returns the path if found, otherwise null.
+ */
+function findProjectConfig(startDir: string): string | null {
+  let dir = path.resolve(startDir)
+  const root = path.parse(dir).root
+
+  while (true) {
+    const candidate = path.join(dir, ".pi", "dcp.jsonc")
+    if (fs.existsSync(candidate)) return candidate
+    if (dir === root) return null
+    const parent = path.dirname(dir)
+    if (parent === dir) return null
+    dir = parent
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/**
+ * Load the DCP configuration by merging (in order):
+ *  1. Built-in defaults
+ *  2. ~/.config/pi/dcp.jsonc  (global; auto-created if missing)
+ *  3. $PI_CONFIG_DIR/dcp.jsonc  (if env var is set)
+ *  4. <project>/.pi/dcp.jsonc  (walked up from projectDir)
+ */
+export function loadConfig(projectDir: string): DcpConfig {
+  // Layer 1: defaults (deep clone so we never mutate the constant)
+  let config: DcpConfig = deepMerge(DEFAULT_CONFIG, {})
+
+  // Layer 2: global config
+  const globalConfigPath = path.join(os.homedir(), ".config", "pi", "dcp.jsonc")
+  ensureGlobalConfig(globalConfigPath)
+  const globalRaw = readJsoncFile(globalConfigPath)
+  if (Object.keys(globalRaw).length > 0) {
+    config = deepMerge(config, globalRaw as Partial<DcpConfig>)
+  }
+
+  // Layer 3: $PI_CONFIG_DIR/dcp.jsonc
+  const piConfigDir = process.env["PI_CONFIG_DIR"]
+  if (piConfigDir) {
+    const envConfigPath = path.join(piConfigDir, "dcp.jsonc")
+    const envRaw = readJsoncFile(envConfigPath)
+    if (Object.keys(envRaw).length > 0) {
+      config = deepMerge(config, envRaw as Partial<DcpConfig>)
+    }
+  }
+
+  // Layer 4: project-local config (walk up from projectDir)
+  const projectConfigPath = findProjectConfig(projectDir)
+  if (projectConfigPath) {
+    const projectRaw = readJsoncFile(projectConfigPath)
+    if (Object.keys(projectRaw).length > 0) {
+      config = deepMerge(config, projectRaw as Partial<DcpConfig>)
+    }
+  }
+
+  return config
+}