OpenDevicePartnership
diff --git a/‎AGENTS.md‎
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Lines changed: 78 additions & 67 deletions
diff --git a/‎CHANGELOG.md‎
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@@ -19,16 +19,25 @@ I²C temperature sensor, built on `embedded-hal` 1.0 and
 device description (`tmp108.toml`) by the
 [`device-driver`](https://crates.io/crates/device-driver) crate.
 
-Two public driver structs:
-
-- `Tmp108<I2C>` — the bare driver. Available in both blocking
-  (`embedded-hal`) and async (`embedded-hal-async`) flavors, gated by
-  the `async` cargo feature, generated from a single source via
-  [`maybe-async-cfg`](https://crates.io/crates/maybe-async-cfg).
-- `AlertTmp108<I2C, ALERT>` — wraps `Tmp108` with an `embedded-hal` /
-  `embedded-hal-async` GPIO pin so it can implement
+Public driver types:
+
+- `Tmp108<I2C>` — the blocking driver, built on
+  [`embedded_hal::i2c::I2c`]. Always available.
+- `AsyncTmp108<I2C>` — the async driver, built on
+  [`embedded_hal_async::i2c::I2c`]. Gated by the `async` cargo
+  feature. Unlocks `AsyncTmp108::continuous`, which has no blocking
+  equivalent (see README's "Gotchas").
+- `AlertTmp108<I2C, ALERT>` — wraps `AsyncTmp108` with an
+  `embedded-hal` / `embedded-hal-async` GPIO pin so it can implement
   `embedded-sensors-hal-async::TemperatureThresholdWait`. Async-only.
-  Gated by `cfg(all(feature = "embedded-sensors-hal-async", feature = "async"))`.
+  Gated by `cfg(feature = "embedded-sensors-hal-async")`. Access the
+  inner sensor via `sensor()` / `sensor_mut()` / `into_inner()`.
+
+Since 0.7.0 both `Tmp108` and `AsyncTmp108` are available
+simultaneously when both features are enabled. The shared
+sync/async-agnostic register codec lives in a private `mod ops`; the
+two driver types are thin shells that perform I²C and delegate the
+meaningful work to `ops::*`.
 
 [datasheet]: https://www.ti.com/lit/gpn/tmp108
 
@@ -42,7 +51,14 @@ Two public driver structs:
 2. [`docs/superpowers/specs/2026-06-03-tmp108-agent-usage-docs-design.md`](docs/superpowers/specs/2026-06-03-tmp108-agent-usage-docs-design.md)
    if you're touching docs/examples — it captures the doctest +
    snippet-marker invariants.
-3. `CONTRIBUTING.md` for the commit-message convention (Conventional
+3. [`docs/superpowers/specs/2026-06-03-tmp108-reliability-fixes-design.md`](docs/superpowers/specs/2026-06-03-tmp108-reliability-fixes-design.md)
+   for the rationale behind the current `Error<E, P>` shape, the
+   `set_*_limit` rejection contract, the `continuous()` cleanup
+   contract, and the hysteresis snapping band.
+4. [`docs/superpowers/specs/2026-06-04-tmp108-type-split-design.md`](docs/superpowers/specs/2026-06-04-tmp108-type-split-design.md)
+   for the rationale behind the `Tmp108` / `AsyncTmp108` split and the
+   `mod ops` shared codec.
+5. `CONTRIBUTING.md` for the commit-message convention (Conventional
    Commits v1.0.0) and the "each commit builds clean" rule.
 
 ---
@@ -53,17 +69,19 @@ Two public driver structs:
 .
 ├── Cargo.toml              # MSRV 1.90; edition 2024; deny-list lints
 ├── tmp108.toml             # device-driver register description
+├── CHANGELOG.md            # Keep-a-Changelog v1.1.0 format
 ├── src/
-│   ├── lib.rs              # Tmp108 + AlertTmp108 + Config + Error + traits
+│   ├── lib.rs              # Tmp108 + AsyncTmp108 + AlertTmp108 +
+│   │                       # Config + Error + private mod ops + traits
 │   └── inner.rs            # GENERATED by device-driver from tmp108.toml — do not hand-edit
 ├── examples/               # All five examples run on Pico de Gallo (see below)
-│   ├── oneshot.rs
-│   ├── continuous.rs           # async-only
+│   ├── oneshot.rs              # blocking OR async, depending on features
+│   ├── continuous.rs           # async-only (AsyncTmp108)
 │   ├── alert_interrupt.rs      # async + embedded-sensors-hal-async
 │   ├── alert_comparator.rs     # async + embedded-sensors-hal-async
 │   └── sensor_trait.rs         # blocking OR async, depending on features
 ├── tests/
-│   └── reexports.rs        # compile-only: pins crate-root re-exports
+│   └── reexports.rs        # compile-only: pins Tmp108 + AsyncTmp108
 ├── scripts/
 │   └── check-readme-snippets.sh    # CI gate: README in sync with examples/
 ├── supply-chain/           # cargo-vet audits
@@ -80,19 +98,23 @@ Two public driver structs:
 | Feature | Effect | Implies |
 |---|---|---|
 | (none) | blocking `Tmp108` over `embedded-hal` | — |
-| `async` | async `Tmp108` over `embedded-hal-async`; unlocks `Tmp108::continuous` | — |
-| `embedded-sensors-hal` | blocking `TemperatureSensor` trait impl | — |
-| `embedded-sensors-hal-async` | async `TemperatureSensor`, `TemperatureThresholdSet`, `TemperatureHysteresis`; `AlertTmp108` wrapper | **requires** `async` |
+| `async` | async `AsyncTmp108` over `embedded-hal-async`; unlocks `AsyncTmp108::continuous` | — |
+| `embedded-sensors-hal` | blocking `TemperatureSensor` trait impl on `Tmp108` | — |
+| `embedded-sensors-hal-async` | async `TemperatureSensor`, `TemperatureThresholdSet`, `TemperatureHysteresis` on `AsyncTmp108`; `AlertTmp108` wrapper | **`async`** (forced in Cargo.toml since 0.7.0) |
 
 Things that follow from the matrix and trip up new contributors:
 
+- `AsyncTmp108` only exists under `cfg(feature = "async")`. The
+  blocking `Tmp108` is always available.
 - `AlertTmp108` and everything that takes an `ALERT` pin **only exist**
-  under `cfg(all(feature = "embedded-sensors-hal-async", feature = "async"))`.
-- `Tmp108::continuous` only exists under `cfg(feature = "async")`. There
-  is **no blocking equivalent**. The README's `Gotchas` section
+  under `cfg(feature = "embedded-sensors-hal-async")` (which forces
+  `async`).
+- `AsyncTmp108::continuous` only exists under `cfg(feature = "async")`.
+  There is **no blocking equivalent**. The README's "Gotchas" section
   documents the workaround.
 - `cargo hack --feature-powerset check --locked` enumerates every legal
-  combination and must stay green. Use it before pushing.
+  combination (6 since 0.7.0, down from 8 because `embedded-sensors-hal-async`
+  now implies `async`). All combos must stay green. Use it before pushing.
 
 ---
 
@@ -181,44 +203,31 @@ build time (actually committed for now, but it's machine output).
 Modify `tmp108.toml` for register-layout changes; everything else
 flows from there.
 
-### 3. The `maybe-async-cfg` pattern in `src/lib.rs`
-
-Most methods on `Tmp108` are written **once** under
-`#[maybe_async_cfg::maybe(...)]` and the macro expands to either the
-blocking or the async variant based on the `async` feature. This means:
-
-- A single function declaration produces *two* different real
-  functions, only one of which is compiled at a time.
-- Doctests cannot satisfy both signatures with the same body — the
-  blocking variant takes `.unwrap()`, the async variant needs
-  `.await.unwrap()`.
-- Our doctests use a cfg-gated `# fn main()` trick to target the
-  blocking signature under `cargo test --doc` (default features) and
-  become inert under `-F async`:
-
-  ```rust
-  /// ```
-  /// # use embedded_hal_mock::eh1::i2c::{Mock, Transaction};
-  /// # #[cfg(feature = "async")] fn main() {}
-  /// # #[cfg(not(feature = "async"))]
-  /// # fn main() {
-  /// use tmp108::Tmp108;
-  /// let i2c = Mock::new(&[
-  ///     Transaction::write_read(0x48, vec![0x00], vec![0x32, 0x00]),
-  /// ]);
-  /// let mut tmp = Tmp108::new_with_a0_gnd(i2c);
-  /// let temp = tmp.temperature().unwrap();
-  /// assert!((temp - 50.0).abs() < 0.01);
-  /// # let mut i2c = tmp.destroy();
-  /// # i2c.done();
-  /// # }
-  /// ```
-  ```
-
-  Follow this exact pattern when adding doctests on any
-  `maybe_async_cfg`'d method. Don't reinvent it.
-
-### 4. `Tmp108::continuous` requires `async |t| { ... }`
+### 3. Two parallel driver types share a private `mod ops`
+
+Since 0.7.0 the driver is implemented as two named types:
+
+- `pub struct Tmp108<I2C: embedded_hal::i2c::I2c>` — always available.
+- `pub struct AsyncTmp108<I2C: embedded_hal_async::i2c::I2c>` —
+  `#[cfg(feature = "async")]`.
+
+Both delegate all chip-specific logic (Celsius↔raw conversion,
+limit-range validation, hysteresis snapping, `Config` ↔ register-byte
+codec) to a private `mod ops` of pure functions. The two driver
+shells are otherwise mirrors of each other; when adding a new method
+on one, add the matching one on the other and route the shared logic
+through `ops::*`.
+
+Doctests are independent per type: `Tmp108` doctests use the plain
+blocking shape, `AsyncTmp108` doctests wrap their body in
+`tokio::runtime::Runtime::new().unwrap().block_on(async { ... })`.
+Don't try to share doctest bodies — the macro shim from earlier
+versions is gone, and the architect's review (see
+`docs/superpowers/specs/2026-06-04-tmp108-type-split-design.md`)
+explicitly chose source-duplication-with-shared-codec over
+maybe-async-cfg precisely because of how cleanly this separates.
+
+### 4. `AsyncTmp108::continuous` requires `async |t| { ... }`
 
 The signature is `F: AsyncFnOnce(&mut Self) -> Result<(), I2C::Error>`
 — Rust's native async-closure syntax (`async |t| { ... }`, stable
@@ -234,11 +243,11 @@ correct templates. Copy from them, not from the old README.
 ### 5. `Config` field-type re-exports are public surface
 
 `tmp108::{Mode, Thermostat, ConversionRate, Hysteresis, Polarity}` are
-`pub use`'d at the crate root via `src/lib.rs:34`. Without them,
-downstream consumers cannot construct a non-default `Config`. There is
-a compile-only test in `tests/reexports.rs` that pins all five names —
-removing or renaming any of them breaks that test and is a
-**breaking change**.
+`pub use`'d at the crate root. Without them, downstream consumers
+cannot construct a non-default `Config`. There is a compile-only test
+in `tests/reexports.rs` that pins all five names plus `Tmp108` and
+(under `-F async`) `AsyncTmp108` — removing or renaming any of them
+breaks that test and is a **breaking change**.
 
 ### 6. Each commit must build clean and pass clippy/fmt independently
 
@@ -405,22 +414,24 @@ certify the Developer Certificate of Origin.
 
 | You're adding… | Put it here |
 |---|---|
-| A new public method on `Tmp108`/`AlertTmp108` | `src/lib.rs`, with a `# Examples` doctest |
+| A new public method that should exist on both driver flavors | Add it **twice**: once on `Tmp108` (blocking impl), once on `AsyncTmp108` (async impl). Put any sync/async-agnostic helper logic in `mod ops`; each method body should be a thin shell that performs I²C and calls into `ops::*`. Both methods need their own `# Examples` doctest in the right shape (blocking vs `tokio::block_on(async {…})`). |
+| A new public method on `AlertTmp108` | `src/lib.rs`, in the `AlertTmp108` impl block, with a `tokio::block_on`-wrapped doctest. Use `self.sensor()` / `self.sensor_mut()` to reach the inner `AsyncTmp108`; do not access the private `tmp108` field. |
 | A new register field | `tmp108.toml`, regenerate `src/inner.rs` if needed |
 | A new example | `examples/<name>.rs`, with `//!` block stating hardware + features + register interactions; add to the CI matrix in `.github/workflows/check.yml` |
 | A new doctest pattern | If it's reusable, document it in this file under "Gotchas" |
-| A new test (unit) | `src/lib.rs` `mod tests` |
+| A new test (unit) | `src/lib.rs` `mod tests` (pure-function tests go in `mod tests::ops_tests`; blocking-driver tests go in `mod tests::blocking`; async-driver tests go in `mod tests::asynchronous`) |
 | A new test (integration) | `tests/<topic>.rs` |
 | A new dev-dep | `Cargo.toml [dev-dependencies]` + a `[[audits.<crate>]]` entry |
 | A README usage snippet | Marker region in an example file + matching `<!-- snippet: NAME -->` block in `README.md`; register in `scripts/check-readme-snippets.sh` |
 | A design document | `docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md` |
 | An implementation plan | `docs/superpowers/plans/YYYY-MM-DD-<topic>.md` |
+| A user-visible change | An entry in `CHANGELOG.md` under the next-unreleased version's appropriate section |
 
 ---
 
 ## When in doubt
 
-Read the source. `src/lib.rs` is ~1,700 lines (most of it `# Examples`
+Read the source. `src/lib.rs` is ~2,850 lines (most of it `# Examples`
 doctests and an `mod tests` that shows every register interaction the
 driver performs at the wire level). The doctests show how each public
 method is meant to be used. The examples show end-to-end workflows on
 
@@ -4,6 +4,74 @@ All notable changes to this project are documented here. The format is
 based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) and
 this project adheres to [Semantic Versioning](https://semver.org/).
 
+## [0.7.0] — 2026-06-04
+
+An architectural refactor: the single `maybe-async-cfg`-generated
+`Tmp108<I2C>` is replaced by two named driver types, **`Tmp108`** for
+the blocking flavor and **`AsyncTmp108`** for the async flavor. Both
+are now available simultaneously when both relevant features are
+enabled. The shared register codec lives in a new private `mod ops`.
+
+### Breaking
+
+- The async driver type is now `AsyncTmp108<I2C>` (was `Tmp108<I2C>`
+  under `feature = "async"`). The blocking `Tmp108<I2C>` is
+  unchanged. **Migration:** in async code, replace `use tmp108::Tmp108;`
+  with `use tmp108::AsyncTmp108;` and rename references accordingly.
+- `AlertTmp108::tmp108` is no longer a public field. **Migration:**
+  use the new `sensor()` / `sensor_mut()` accessors, or `into_inner()`
+  to destructure into `(AsyncTmp108<I2C>, ALERT)`.
+- The `embedded-sensors-hal-async` feature now implicitly enables
+  `async` (it was previously possible to build dead code by enabling
+  the trait feature without `async`). Callers who listed both
+  explicitly are unaffected.
+- `Tmp108::into_alert` is removed; the equivalent now lives only on
+  `AsyncTmp108::into_alert`, where it is the correct flavor (the
+  bare blocking driver never had a coherent path to the async-only
+  `AlertTmp108` wrapper).
+- `AsyncTmp108::continuous` is async-only and lives only on the
+  async driver type (it previously lived on `Tmp108` under
+  `feature = "async"` and was awkwardly cfg-gated within a
+  maybe-async-cfg'd impl block).
+
+### Added
+
+- `AsyncTmp108<I2C>` driver type, parallel in surface to `Tmp108`.
+  Both flavors expose: `new`, `new_with_a0_gnd/vplus/sda/scl`,
+  `addr`, `destroy`, `probe`, `read_configuration`, `configure`,
+  `temperature`, `one_shot`, `shutdown`, `wait_for_temperature`,
+  `low_limit`, `set_low_limit`, `high_limit`, `set_high_limit`.
+  `AsyncTmp108` additionally provides `continuous` and
+  `into_alert`.
+- `AlertTmp108::sensor() -> &AsyncTmp108<I2C>` and
+  `AlertTmp108::sensor_mut() -> &mut AsyncTmp108<I2C>` replace the
+  former `pub tmp108` field.
+- `AlertTmp108::into_inner(self) -> (AsyncTmp108<I2C>, ALERT)` —
+  inverse of `AsyncTmp108::into_alert`.
+- `Eq` and `Hash` on `Config`.
+- Conditional `Clone`, `Copy`, `PartialEq`, `Eq` on `Error<E, P>`
+  (when `E` and `P` implement the corresponding trait).
+- First-class doctest coverage for the async driver. Doctest count
+  with `--all-features` rises from 18 to 47.
+
+### Internal
+
+- The driver no longer depends on `maybe-async-cfg`. The two driver
+  types are written out directly and share their meaningful logic
+  through a private `mod ops` of pure functions
+  (`to_celsius`, `to_raw`, `snap_hysteresis`, `decode_config`,
+  `apply_config`, plus the relevant constants).
+- The internal `Interface` is split into a blocking `Interface`
+  (always available) and an async `AsyncInterface`
+  (`#[cfg(feature = "async")]`). Each implements the matching
+  `device-driver` register-interface trait.
+- The `# fn main()` doctest workaround (formerly Gotcha 3 in
+  AGENTS.md) is gone — each type has its own doctests with the
+  correct shape for its flavor.
+- `cargo hack --feature-powerset` matrix shrinks from 8 to 6 legal
+  combinations (the two combos that disabled `async` while enabling
+  `embedded-sensors-hal-async` are gone).
+
 ## [0.6.0] — 2026-06-03
 
 A reliability-focused release. Several `Error` paths and `Tmp108`