feat: add Cursor, Codex, and OpenCode harnesses — maximize every AI coding tool

- AGENTS.md: universal cross-tool file read by Claude Code, Cursor, Codex, and OpenCode
- .cursor/: 15 hook events via hooks.json, 16 hook scripts with DRY adapter pattern,
  29 rules (9 common + 20 language-specific) with Cursor YAML frontmatter
- .codex/: reference config.toml, Codex-specific AGENTS.md supplement,
  10 skills ported to .agents/skills/ with openai.yaml metadata
- .opencode/: 3 new tools (format-code, lint-check, git-summary), 3 new hooks
  (shell.env, experimental.session.compacting, permission.ask), expanded instructions,
  version bumped to 1.6.0
- README: fixed Cursor section, added Codex section, added cross-tool parity table
- install.sh: now copies hooks.json + hooks/ for --target cursor

.opencode/tools/lint-check.ts

@@ -0,0 +1,74 @@
+/**
+ * ECC Custom Tool: Lint Check
+ *
+ * Multi-language linter that auto-detects the project's linting tool.
+ * Supports: ESLint/Biome (JS/TS), Pylint/Ruff (Python), golangci-lint (Go)
+ */
+
+import { tool } from "@opencode-ai/plugin"
+import { z } from "zod"
+
+export default tool({
+  name: "lint-check",
+  description: "Run linter on files or directories. Auto-detects ESLint, Biome, Ruff, Pylint, or golangci-lint.",
+  parameters: z.object({
+    target: z.string().optional().describe("File or directory to lint (default: current directory)"),
+    fix: z.boolean().optional().describe("Auto-fix issues if supported (default: false)"),
+    linter: z.string().optional().describe("Override linter: eslint, biome, ruff, pylint, golangci-lint (default: auto-detect)"),
+  }),
+  execute: async ({ target = ".", fix = false, linter }, { $ }) => {
+    // Auto-detect linter
+    let detected = linter
+    if (!detected) {
+      try {
+        await $`test -f biome.json || test -f biome.jsonc`
+        detected = "biome"
+      } catch {
+        try {
+          await $`test -f .eslintrc.json || test -f .eslintrc.js || test -f .eslintrc.cjs || test -f eslint.config.js || test -f eslint.config.mjs`
+          detected = "eslint"
+        } catch {
+          try {
+            await $`test -f pyproject.toml && grep -q "ruff" pyproject.toml`
+            detected = "ruff"
+          } catch {
+            try {
+              await $`test -f .golangci.yml || test -f .golangci.yaml`
+              detected = "golangci-lint"
+            } catch {
+              // Fall back based on file extensions in target
+              detected = "eslint"
+            }
+          }
+        }
+      }
+    }
+
+    const fixFlag = fix ? " --fix" : ""
+    const commands: Record<string, string> = {
+      biome: `npx @biomejs/biome lint${fix ? " --write" : ""} ${target}`,
+      eslint: `npx eslint${fixFlag} ${target}`,
+      ruff: `ruff check${fixFlag} ${target}`,
+      pylint: `pylint ${target}`,
+      "golangci-lint": `golangci-lint run${fixFlag} ${target}`,
+    }
+
+    const cmd = commands[detected]
+    if (!cmd) {
+      return { success: false, message: `Unknown linter: ${detected}` }
+    }
+
+    try {
+      const result = await $`${cmd}`.text()
+      return { success: true, linter: detected, output: result, issues: 0 }
+    } catch (error: unknown) {
+      const err = error as { stdout?: string; stderr?: string }
+      return {
+        success: false,
+        linter: detected,
+        output: err.stdout || "",
+        errors: err.stderr || "",
+      }
+    }
+  },
+})