SDK: typed PmClient fields apply CLI sentinels ('-' reads stdin, 'none' clears), silently corrupting imported data #1614

Problem

The typed SDK applies the CLI's input sentinels to literal values. An integration that writes provider data through PmClient silently loses or replaces data whenever a provider value happens to equal a sentinel. Reproduced with @unbrained/pm-cli 2026.10.27, Node 24.19, stdin closed:

On the CLI, --description - meaning "read stdin" and --assignee none meaning "clear" are reasonable. Typed SDK fields carry data, though, and the caller already has a dedicated way to express "clear" (null / an explicit unset). A Linear issue whose body is -, or a Jira user literally named none, is rewritten on import with no warning. Downstream preview/conflict code that hashes the provider value then reports false conflicts forever (found while reviewing pm-linear field-ownership previews, unbraind/pm-linear#183).

Repro

import { PmClient } from '@unbrained/pm-cli/sdk';
const c = new PmClient({ pmRoot: `${process.cwd()}/.agents/pm`, author: 'probe' });
const { item } = await c.create({ type: 'Task', title: 't', description: 'd', assignee: 'alice' });
await c.update(item.id, { description: '-' });   // stdin consumed; description -> ""
await c.update(item.id, { assignee: 'none' });    // assignee cleared
console.log((await c.get(item.id)).item);

(Run with < /dev/null. Under a pipeline that has stdin, the description silently becomes whatever is on stdin.)

Expected

• SDK option values are literal. Sentinels (- for stdin, none/empty for clear, @file) exist only in CLI argument parsing.
• The SDK expresses clearing with null or a typed unset option, never with a magic string.
• If keeping compatibility requires an opt-in, use something like new PmClient({ cliSentinels: true }). The default must be literal, and an SDK call should never read process stdin implicitly.
• Add a conformance test: every string field round-trips every CLI sentinel byte-for-byte through create/update/append, and no SDK call reads stdin.