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Parity: cite the generated surface report instead of re-asserting it - #213

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Follow-up to #212, which made "what does Dapper.AOT do with this overload?" a derived fact. This stops parity.md answering that question from memory.

  • ApiSurface.expected.txt is named as the source of truth for API-surface status, with the three things it deliberately does not cover spelled out: behaviour, per-call-site refusals, and non-extension statics (Format, PackListParameters, LookupDbType, TypeHandlerCache<T> — called directly rather than intercepted, so the generator has no opinion and nothing measures whether they are AOT-safe when called).
  • Three ❓ rows are settled by the report and now cite it: Parse (all three overloads sit outside the generator's name filter — emitted nothing, said nothing), Format/ReplaceLiterals (same, and Format is not even an extension method), and CommandDefinition.
  • CommandDefinition was the worst of the stale rows. It read as an unverified question about CommandFlags.Pipelined. It is in fact 27 overloads, every one skipped in silence — high impact, not the "med" it carried. Split into the overload row and a separate CommandFlags row, since the latter is moot at a call-site until the former is fixed.
  • The delta summary leads with both measurements, because they answer different questions: 40 of 110 overloads tell the consumer nothing, and 677 of 793 corpus tests pass.
  • Adds a row 0 — say something at those 40 mute overloads. It supports no new API and is small, but it converts a silent runtime AOT failure into a build warning, which makes it the cheapest safety item on the list.

Remaining ❓ now means "needs a corpus run to settle" unless a row says otherwise; the few things nothing measures are marked uninstrumented in place.

Notes only — no code changes.

#212 made "what does Dapper.AOT do with this overload?" a derived fact, so this
stops the table answering it from memory. ApiSurface.expected.txt is named as
the source of truth, with the three things it deliberately does not cover -
behaviour, per-call-site refusals, and non-extension statics like Format and
LookupDbType, which are called rather than intercepted.

Three ❓ rows are settled by the report and now cite it: Parse (all three
overloads sit outside the generator's name filter), Format/ReplaceLiterals
(same, and Format is not even an extension method), and CommandDefinition -
which was the worst of the stale rows. It read as an unverified question about
CommandFlags.Pipelined; it is in fact 27 overloads, every one skipped in
silence, which is high impact rather than the "med" it carried. Split into the
overload row and a separate CommandFlags row, since the second is moot until the
first is fixed.

The delta summary now leads with both measurements rather than one, because they
answer different questions: 40 of 110 overloads tell the consumer nothing, and
677 of 793 corpus tests pass. Adds a row 0 - saying *something* at those 40 - as
the cheapest item on the list: it supports no new API, and turns a silent
runtime AOT failure into a build warning.

Remaining ❓ now means "needs a corpus run" unless a row says otherwise.
@mgravell
mgravell merged commit bebc9e4 into main Aug 26, 2026
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mgravell added a commit that referenced this pull request Sep 11, 2026
`state-of-play.md` is the "read first after a break" page and was the most wrong
thing in the repo: it still listed #206/#207/#208 as in flight with a landing order
to follow, and knew nothing of #209-#216. It now says what is true - nothing of ours
in flight, the four open PRs are all external and all awaiting a decision.

It also absorbs the account of **why #206 was closed**, which was sitting unmerged on
the `typehandler-registration-note` branch and existed nowhere in main: gating stopped
the bridge emitting for consumers who did not opt in, but the read-side check still
sat in `RowFactory.GetValue<T>` - the type-flexible arm of every mapped member - so
everyone paid for a feature almost nobody would enable. The emission-time fix that
was considered and rejected is recorded with it, since that is the part most likely
to be re-proposed.

Two things promoted, because they gate real work and were buried:

- the behavioural harness is local-only and does **not** exist on this machine (no
  `aot-harness` branch, no SQL Server, Windows-shaped repack recipe), so no phase-3
  round can be closed and 677/793 cannot be re-measured until it is rebuilt;
- net48 is unverified since #216 and #214, both of which changed interceptor goldens.

Corrections: #117 and #162 are closed, not awaiting a decision; the `type-handler`
branch harvest was filed as "before #208 settles", and #208 has settled; diagnostic
ids as actually shipped (DAP053-056, next free DAP057).

`parity.md`: the `CommandDefinition` row still said "27 overloads, every one skipped
silently" - #214 moved the `Type`+`CommandDefinition` combinations out, so it is 21
of the 22 in that bucket. Cites the report rather than restating a number, which is
what #213 was for.

Also: `typehandlers-design.md` never existed in main - it was a file on the closed
#206 branch - leaving dangling links in three notes. Pointed at the note that did
land, `typehandler-registration.md`.
@mgravell
mgravell deleted the parity-from-report branch September 11, 2026 13:34
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