`pmacs.editor.take_typed_edit()` is one-shot and per-frontend (Q#AP9):
the first `buffer.after-edit` callback to call it clears the slot, and
every later callback in the same fan-out sees nil. That was survivable
only because auto-pairing was the sole consumer — never a property
anyone chose. A second independent caller would get nil or steal the
record from pairing depending on hook registration order, and
registration order is not a contract.
This makes it one. `builtin/runtime/typed_edit.lua` owns the single
after-edit subscriber that reads the record, and offers that one read to
consumers registered through `pmacs.typed_edit.add_consumer{ name,
priority, fn }`: lowest priority first, ties by registration order, and
the first consumer to return truthy claims the edit and stops the chain.
`pair.lua` becomes that chain's only consumer, at priority 100.
No Lean content. Stage 4b's abbreviation expander is what needs the
ordering guarantee (64 of its 1,855 keys contain a `lean4` pair-set
character, so pairing running first corrupts them), but the chain is
substrate every language runs through, which is why it ships alone —
framing Q#LN10, and §4's rule that no PR in this arc mixes a
cross-cutting substrate change with Lean feature content.
Three design points worth review attention:
- Consumers are called even when the record is nil. "This fan-out
carried no typed edit" is information a consumer acts on: it is how
pairing's test seam observes a non-event, and how Stage 4b will
abandon a pending abbreviation an unrelated edit invalidated. Three
existing auto-pairing tests fail if the chain skips consumers on nil.
- The chain pcalls each consumer. `buffer.after-edit` is
all-must-succeed, so a throwing consumer would otherwise fail the
fan-out for every other subscriber, including lsp.lua's didChange
flush. Behavior-preserving for pairing, which already never throws.
- Ordered insertion, not `table.sort`, which is not stable in Lua —
"ties by registration order" is a stated contract, not a coincidence.
`tests/auto_pair_acceptance.rs` is UNCHANGED — zero lines — and its 45
tests pass. That is criterion 46 and the whole no-behavior-change claim;
a suite edited to accommodate the refactor would prove nothing.
`tests/typed_edit_chain_acceptance.rs` adds 9 tests for criteria
46a-46e. Every one is bite-verified by mutation: appending instead of
ordered insert (5 fail), `>=` for the tiebreak (1), re-taking per
consumer (4), ignoring the claim (1), dropping the pcall (1), skipping
nil fan-outs (1 here plus 3 in the untouched auto-pair suite), and
loading the chain after lsp.lua (the Q#AP7 flush test fails, alongside
the two existing pairing ones).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011LFvC4FQtux4y32KuevZ7B
Levi Neuwirth
24ca906294