emrg: the open-source task template never says a translated document is edited with its twin #2648

What is missing

emrg/server/open_source_prompt.md §3.1.5 (Implement) tells a round what an edit must satisfy — one problem per change, read the surrounding context before editing, follow the conventions read in §3.1.3 and the design intent from the same section — and it never mentions the case where the file being edited exists in more than one language.

Measured on master: the template carries no rule about a translated counterpart at all. grep -n -i "translat\|zh-CN\|bilingual\|twin\|\.cn\.md" emrg/server/open_source_prompt.md returns nothing.

The English-only rule at :24 does not cover this. It governs outward artifacts — PR titles and bodies, review comments, issue replies, commit messages, community participation — not the repository's own documents, and it says nothing about a twin that a change leaves behind.

What that costs

A project that keeps a translated copy of a document — a README, a design note, a user guide, a contributor guide — has two readers of one instruction. A round that updates only the side it was reading leaves the other side stating the old rule, and the next contributor who opens the stale side first is told the opposite of what the project now does. Because nothing in the prompt asks the round to look for a twin in the first place, this is not a mistake only a careless round makes: it is invisible to a careful one too.

The failure is silent in both directions. Nothing in CI fails when two copies disagree, and no test in the target repository compares them, so the divergence is first noticed by a reader.

What the fix must satisfy

1. The rule goes in §3.1.5 Implement, the section that already owns what an edit must satisfy — not appended at the end of the file, and not stated twice anywhere.
2. It says: where the file being changed has a counterpart in another language, both are changed in the same change and read against each other before committing; and where the project states which copy governs a disagreement, that statement sets the order, so the other copy follows it rather than the reverse.
3. It is written in the template's own voice, and it names no particular repository and no installation's paths.
4. A test pins the phrase and the heading that owns it, and requires the phrase to appear exactly once, so a deletion, a duplication and a relocation each redden. The controls are the same two arms the ios-app template's method pin uses: one deletes the phrase, one moves it to the end of the file.