fix(coding-agent): list PI_RULES settings in --help

packages/coding-agent/src/cli/args.ts

@@ -433,6 +433,9 @@ ${chalk.bold("Environment Variables:")}
   ${ENV_SESSION_DIR.padEnd(32)} - Session storage directory (overridden by --session-dir)
   PI_PACKAGE_DIR                   - Override package directory (for Nix/Guix store paths)
   PI_OFFLINE                       - Disable startup network operations when set to 1/true/yes
+  PI_RULES_DISABLED                - Disable built-in rules when set to 1/true/yes/on
+  PI_RULES_MAX_RULE_CHARS          - Per-rule formatted payload character cap (default: 12000)
+  PI_RULES_MAX_RESULT_CHARS        - Complete static/dynamic block character cap (default: 40000)
   PI_TELEMETRY                     - Override install telemetry when set to 1/true/yes or 0/false/no
   PI_SHARE_VIEWER_URL              - Base URL for /share command (default: https://pi.dev/session/)
 

packages/coding-agent/src/cli/changes.md

@@ -1,5 +1,26 @@
 # changes
 
+## PI_RULES environment settings in top-level help (2026-08-03)
+
+### What changed
+
+- `args.ts`: the Environment Variables section now lists `PI_RULES_DISABLED`,
+  `PI_RULES_MAX_RULE_CHARS`, and `PI_RULES_MAX_RESULT_CHARS` with their accepted values and defaults.
+
+### Why
+
+- The settings added in #670 were documented in the README but omitted from `senpi --help`, leaving the two
+  environment-only character limits undiscoverable from the CLI.
+
+### Why extension system couldn't handle this
+
+- The static Environment Variables section belongs to `printHelp()` and extensions can register flags, not help
+  entries for environment settings.
+
+### Expected merge conflict zones on next upstream sync
+
+- LOW: `args.ts` Environment Variables rows.
+
 ## `senpi --list-tips` prints the tip catalog as JSON (2026-07-29)
 
 ### What changed

packages/coding-agent/test/suite/regressions/678-pi-rules-help-env.test.ts

@@ -0,0 +1,20 @@
+import { expect, test, vi } from "vitest";
+import { printHelp } from "../../../src/cli/args.ts";
+
+test("lists the public PI_RULES environment settings in top-level help", () => {
+	// Given: the top-level help output is captured without loading extension flags.
+	const logSpy = vi.spyOn(console, "log").mockImplementation(() => {});
+
+	try {
+		// When: the CLI renders its built-in help surface.
+		printHelp(undefined, false);
+		const output = logSpy.mock.calls.map(([message]) => String(message)).join("\n");
+
+		// Then: every public rules setting is discoverable by name.
+		expect(output).toContain("PI_RULES_DISABLED");
+		expect(output).toContain("PI_RULES_MAX_RULE_CHARS");
+		expect(output).toContain("PI_RULES_MAX_RESULT_CHARS");
+	} finally {
+		logSpy.mockRestore();
+	}
+});