Update hephaestus with all the power it brings

.github/workflows/autofmt.yaml

@@ -51,7 +51,7 @@ jobs:
           gh pr checkout ${{ github.event.issue.number }} --repo "$GITHUB_REPOSITORY"
 
       - name: Install Rust (rustfmt)
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt
 

.github/workflows/build.yaml

@@ -40,32 +40,39 @@ jobs:
         # which invokes `protoc` at build time. Required for the ADBC test path.
         run: sudo apt-get install -y protobuf-compiler
 
-      - name: Install png writer system libraries
-        # The png writer renders via wgpu/Vello, which needs a Vulkan
-        # adapter. ubuntu-latest has no GPU, so install Mesa's lavapipe software
-        # device. If no adapter is found anyway, the writer test skips its render
-        # assertion gracefully rather than failing.
-        # Text layout goes through parley/fontique, which links the system
-        # fontconfig on Linux to enumerate fonts, so its development files
-        # (fontconfig.pc plus headers) must be present at build time.
-        run: sudo apt-get install -y mesa-vulkan-drivers libfontconfig1-dev
+      - name: Install renderer system libraries
+        # Two separate needs, conflated easily:
+        #
+        # * mesa-vulkan-drivers is for the *raster* writers and the plot
+        #   viewer, which render through wgpu and need a Vulkan adapter.
+        #   ubuntu-latest has no GPU, so this installs Mesa's lavapipe software
+        #   device. Without an adapter those tests skip their render assertion
+        #   rather than fail.
+        # * fontconfig is for *every* renderer-backed feature including svg,
+        #   pdf and hep: text layout goes through parley/fontique, which
+        #   enumerates fonts through the system fontconfig whatever draws.
+        #
+        # Only the fontconfig *runtime* library is installed, deliberately:
+        # ggsql enables fontique's `fontconfig-dlopen`, so the `-dev` package
+        # is not needed at build time, and leaving it out makes every CI run a
+        # regression test for that. fonts-dejavu-core gives fontconfig
+        # something to find.
+        run: sudo apt-get install -y mesa-vulkan-drivers libfontconfig1 fonts-dejavu-core
 
       - name: Install Rust
-        # 1.86 is the MSRV (declared as `rust-version` in /Cargo.toml, see
-        # /CLAUDE.md); this sets it as the default toolchain so plain `cargo`
-        # uses it. fmt, clippy and the library build run on 1.86 to guarantee
-        # the shipped crate builds there.
-        uses: dtolnay/rust-toolchain@1.86.0
+        # Stable is the default toolchain. It is *not* the MSRV: `rust-version`
+        # in /Cargo.toml is 1.86 (CRAN's), which is what points clippy's
+        # MSRV-aware lints at 1.86 — so running clippy here still guards it.
+        # The default cannot be 1.86 itself, because the default writers pull
+        # `parley`, which declares 1.88, and the `adbc` test path needs 1.88
+        # for real.
+        uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt, clippy
 
-      - name: Install Rust (test toolchain)
-        # The experimental `adbc` feature's test path pulls `adbc_datafusion` →
-        # `datafusion` ≥53.1.0, which requires rustc ≥1.88. Steps that compile
-        # tests/dev-dependencies use this newer toolchain via `cargo +stable`.
-        # Installing it here does not change the default — plain `cargo` stays
-        # on 1.86.
-        run: rustup toolchain install stable --profile minimal
+      - name: Install Rust (CRAN toolchain)
+        # For the MSRV check below only. Does not change the default.
+        run: rustup toolchain install 1.86 --profile minimal
 
       - name: Caching
         uses: Swatinem/rust-cache@v2
@@ -81,42 +88,64 @@ jobs:
         run: cargo clippy -- -D warnings
 
       - name: Install wasm-pack
-        # `cargo install` runs at the repo root, where 1.86 is the default;
-        # `+stable` builds the tool on the newer toolchain. The actual wasm build
-        # below runs in ggsql-wasm/, whose nested rust-toolchain.toml selects stable.
-        run: cargo +stable install wasm-pack
+        # The wasm build itself runs in ggsql-wasm/, whose nested
+        # rust-toolchain.toml selects stable.
+        run: cargo install wasm-pack
 
-      - name: Build library (MSRV 1.86)
+      - name: Build library
         run: cargo build
 
       - name: Build all targets
-        # --all-targets compiles dev-dependencies (datafusion), so it needs ≥1.88.
-        run: cargo +stable build --all-targets
+        run: cargo build --all-targets
+
+      - name: Check the library builds on CRAN's toolchain (MSRV 1.86)
+        # The R package vendors ggsql and CRAN builds it on 1.86, so the code
+        # has to keep compiling there. `--ignore-rust-version` is needed only
+        # because `parley` *declares* 1.88 while compiling fine on 1.86 — do
+        # not delete the flag; delete this job and the MSRV silently rots.
+        #
+        # Library only, not --all-targets: the `adbc` dev-dependency path pulls
+        # datafusion, which uses let-chains and genuinely requires 1.88.
+        run: cargo +1.86 check --ignore-rust-version -p ggsql
 
       - name: Run tree-sitter tests
         working-directory: tree-sitter-ggsql
         run: tree-sitter test
 
       - name: Run Rust tests
-        run: cargo +stable test --lib --bins
+        run: cargo test --lib --bins
 
       - name: Install dbc CLI and SQLite ADBC driver
         run: |
           curl -LsSf https://dbc.columnar.tech/install.sh | sh
           "$HOME/.local/bin/dbc" install sqlite
 
       - name: Run ADBC unit tests
-        run: cargo +stable test --features "adbc sqlite" --lib
+        run: cargo test --features "adbc sqlite" --lib
 
       - name: Run ADBC SQLite equivalence tests
-        run: cargo +stable test --features "adbc sqlite" --lib -- --ignored equivalence
-
-      - name: Run png writer tests
-        # Non-default feature. The hephaestus crate it renders through needs
-        # rustc ≥1.88 (wgpu), so it builds on +stable and is excluded from the
-        # 1.86 library build. Default features (incl. duckdb) supply the
-        # in-memory reader the test uses.
-        run: cargo +stable test --features png --lib writer::hephaestus
+        run: cargo test --features "adbc sqlite" --lib -- --ignored equivalence
+
+      - name: Run GPU-free writer tests
+        # svg, pdf and hep are default features and need no adapter, so these
+        # are hard assertions on every runner. hep-read adds the document
+        # round trip. Fast, and its failure is unambiguous, so it runs first.
+        run: 'cargo test --features hep-read --lib writer::'
+
+      - name: Run raster writer tests
+        # Non-default features needing a GPU adapter. Skips its render
+        # assertions gracefully if lavapipe did not come up.
+        run: 'cargo test --features "png jpeg tiff webp" --lib writer::'
+
+      - name: Check the plot viewer builds
+        # Not a writer and it blocks on a window, so it is compiled, not run.
+        run: cargo check --features window
+
+      - name: Check the visual-test harness builds
+        # `required-features` keeps it out of every other build here, so
+        # nothing else would catch it failing to compile. Checked, not run:
+        # it renders the whole doc corpus and wants an adapter to do it.
+        run: cargo check -p ggsql-cli --features png --example visual_test
 
       - name: Build WASM library
         working-directory: ggsql-wasm/library

.github/workflows/publish.yaml

@@ -40,16 +40,12 @@ jobs:
         run: sudo apt-get install -y unixodbc-dev
 
       - name: Install Rust
-        # 1.86 is the MSRV (see /CLAUDE.md); this is the default toolchain, and
-        # the Jupyter kernel build below runs on it.
-        uses: dtolnay/rust-toolchain@1.86.0
-
-      - name: Install Rust (wasm toolchain)
-        # The wasm build is exempt from the 1.86 MSRV (R doesn't use wasm); some
-        # wasm-only deps need a newer rustc. Installing stable here does not
-        # change the default — plain `cargo` stays on 1.86, and
-        # ggsql-wasm/rust-toolchain.toml selects stable for the wasm build.
-        run: rustup toolchain install stable --profile minimal
+        # Stable. The MSRV declared in /Cargo.toml is 1.86 — CRAN's, for the R
+        # package's vendored copy (see /CLAUDE.md) — and it is checked by its
+        # own step in build.yaml rather than by pinning here; clippy reads
+        # `rust-version`, not the toolchain. ggsql-wasm/rust-toolchain.toml
+        # selects stable for the wasm build regardless.
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Caching
         uses: Swatinem/rust-cache@v2
@@ -59,12 +55,10 @@ jobs:
           save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Install wasm-pack
-        # `cargo install` runs at the repo root (pinned to 1.86); `+stable`
-        # builds these tools on the newer toolchain instead.
-        run: cargo +stable install wasm-pack
+        run: cargo install wasm-pack
 
       - name: Install wasm-opt
-        run: cargo +stable install wasm-opt
+        run: cargo install wasm-opt
 
       - name: Setup quarto
         uses: quarto-dev/quarto-actions/setup@v2

.github/workflows/release-jupyter.yml

@@ -55,6 +55,14 @@ jobs:
         uses: PyO3/maturin-action@v1
         with:
           target: ${{ matrix.target }}
+          # No feature flags: `raster-plots` is default, precisely so that a
+          # plain build matches the released wheel. It adds the png/jpeg/tiff
+          # writers, which need a GPU adapter at *run* time and fall back to
+          # SVG without one, so a wheel carrying them still works on a
+          # headless machine. No before-script-linux either: ggsql enables
+          # fontique's `fontconfig-dlopen`, so nothing here needs
+          # fontconfig-devel at build time — verified in this exact image,
+          # which does not ship it.
           args: --release --out dist --auditwheel=skip
           working-directory: ggsql-jupyter
           manylinux: 2_28

.github/workflows/release-packages.yml

@@ -27,7 +27,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           targets: x86_64-pc-windows-msvc
 
@@ -110,7 +110,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           targets: x86_64-apple-darwin
 
@@ -224,7 +224,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           targets: aarch64-apple-darwin
 
@@ -338,7 +338,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           targets: x86_64-unknown-linux-gnu
 
@@ -392,7 +392,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
         with:
           targets: aarch64-unknown-linux-gnu
 
@@ -450,7 +450,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Get crates.io publish token
         uses: rust-lang/crates-io-auth-action@v1
@@ -511,7 +511,7 @@ jobs:
         run: npm install -g tree-sitter-cli
 
       - name: Install Rust toolchain
-        # This job only builds wasm, which is exempt from the 1.86 MSRV (R
+        # This job only builds wasm, which is exempt from the MSRV (R
         # doesn't use wasm) and needs a newer rustc, so the whole job runs on
         # stable. ggsql-wasm/rust-toolchain.toml also selects stable for the build.
         uses: dtolnay/rust-toolchain@stable

.github/workflows/test-extension.yaml

@@ -106,7 +106,12 @@ jobs:
           cache-dependency-path: ggsql-vscode/package-lock.json
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@1.86.0
+        # Stable, matching every other job that builds a real binary — and the
+        # kernel released to PyPI. Not the MSRV: that 1.86 floor exists for the
+        # R package's vendored copy of the *library*, and build.yaml checks it
+        # directly. The kernel enables `raster-plots`, so it pulls wgpu and
+        # parley and cannot build on 1.86 at all.
+        uses: dtolnay/rust-toolchain@stable
 
       # Use publish.yaml's cargo cache with `save-if: false`.
       - name: Restore the cargo cache built by publish.yaml