diff --git a/src/main/skill-types.ts b/src/main/skill-types.ts
new file mode 100644
index 00000000..43cfe4f1
--- /dev/null
+++ b/src/main/skill-types.ts
@@ -0,0 +1,114 @@
+// ---------------------------------------------------------------------------
+// Skill system type definitions and constants
+// ---------------------------------------------------------------------------
+
+/**
+ * Source type for a skill -- matches the company_skills.source_type column.
+ */
+export type SkillSourceType =
+  | "github"
+  | "local_path"
+  | "url"
+  | "skills_sh"
+  | "managed";
+
+/**
+ * Trust level derived from the file inventory of a skill package.
+ * Determines what content is injected and how cautiously.
+ */
+export type TrustLevel =
+  | "markdown_only"
+  | "assets"
+  | "scripts_executables";
+
+/**
+ * A single file entry within a skill package inventory.
+ */
+export interface FileInventoryEntry {
+  path: string;
+  kind: "skill" | "reference" | "script" | "asset" | "markdown" | "other";
+}
+
+/**
+ * Full row interface matching the company_skills table.
+ * Property names use camelCase (JS convention) even though DB columns are snake_case.
+ */
+export interface SkillRecord {
+  id: string;
+  companyId: string;
+  key: string;
+  slug: string;
+  name: string;
+  description: string | null;
+  markdown: string;
+  sourceType: SkillSourceType;
+  sourceLocator: string | null;
+  sourceRef: string | null;
+  trustLevel: TrustLevel;
+  compatibility: string;
+  fileInventory: FileInventoryEntry[];
+  metadata: Record<string, unknown> | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+/**
+ * Result returned after importing or updating a skill.
+ */
+export interface SkillImportResult {
+  skillId: string;
+  key: string;
+  name: string;
+  isUpdate: boolean;
+}
+
+/**
+ * Runtime representation of a skill entry for adapter injection.
+ */
+export interface RuntimeSkillEntry {
+  runtimeName: string;
+  sourcePath: string;
+  name: string;
+  tokenEstimate: number;
+}
+
+/**
+ * Minimal skill reference passed to worker threads.
+ * Subset of RuntimeSkillEntry to minimize serialization overhead.
+ */
+export interface ManagedSkillRef {
+  runtimeName: string;
+  sourcePath: string;
+}
+
+/**
+ * Skill-to-agent assignment record.
+ */
+export interface SkillAssignment {
+  agentId: string;
+  skillId: string;
+}
+
+/**
+ * Update status for a skill -- used to check if a newer version is available.
+ */
+export interface SkillUpdateStatus {
+  skillId: string;
+  key: string;
+  currentRef: string | null;
+  latestRef: string | null;
+  hasUpdate: boolean;
+}
+
+/**
+ * Per-adapter token budgets for skill content injection.
+ * Values represent the maximum token count of skill content that can be
+ * included in a single prompt for each adapter type.
+ */
+export const TOKEN_BUDGETS: Readonly<Record<string, number>> = {
+  claude_local: 50000,
+  codex_local: 30000,
+  gemini_local: 50000,
+  opencode_local: 30000,
+  kimi_local: 20000,
+};