Add ub-rust skill for Rust development

.agents/skills/ub-rust/assets/lints-template/Cargo-lints.toml

@@ -0,0 +1,28 @@
+# UB Rust starter lint profile.
+# Merge material for Cargo.toml; not a standalone config file.
+#
+# Workspaces: put these tables under [workspace.lints.rust] and
+# [workspace.lints.clippy] in the root manifest, then add
+# `[lints] workspace = true` to each member crate.
+# Single crates: use them as [lints.rust] and [lints.clippy] directly.
+#
+# Starter only: adapt levels to repo truth before enforcing in CI.
+
+[lints.rust]
+# Keep idiom migration lints visible; priority -1 lets specific
+# lints below override members of this group.
+rust-2018-idioms = { level = "warn", priority = -1 }
+unreachable_pub = "warn"
+unused_must_use = "warn"
+
+[lints.clippy]
+# Baseline correctness/style/complexity/perf groups at warn; specific
+# lints below override members of the groups.
+all = { level = "warn", priority = -1 }
+# High-signal additions beyond the default groups.
+dbg_macro = "warn"
+todo = "warn"
+unimplemented = "warn"
+# Production-path discipline; relax in tests with scoped, justified
+# expect/allow attributes instead of removing the lint.
+unwrap_used = "warn"

.agents/skills/ub-rust/references/cargo-lints-resolution.md

@@ -0,0 +1,70 @@
+# Cargo Lint Policy Resolution
+
+Use this reference when deciding what lint policy actually applies in a target
+repository and whether the bundled lint-table starter should be adopted.
+
+## Resolution Order
+
+1. `[workspace.lints]` in the workspace root `Cargo.toml`, inherited by
+   member crates that declare `[lints] workspace = true`, is the broadest
+   policy surface.
+2. A per-crate `[lints]` table overrides nothing silently: a crate either
+   inherits the workspace table or defines its own.
+3. `clippy.toml` configures individual clippy lint behavior (thresholds,
+   allowed names) but does not set lint levels.
+4. `rustfmt.toml` (or `.rustfmt.toml`) owns formatting; it is separate from
+   lint policy.
+5. CI flags (for example `cargo clippy -- -D warnings`) and environment
+   `RUSTFLAGS` can tighten enforcement beyond the manifest tables; check CI
+   before declaring the real gate.
+
+Treat the combination of manifest tables plus CI flags as the repository's
+real lint policy. Do not present the bundled starter as active policy when
+any explicit policy already exists.
+
+## Toolchain Floor Awareness
+
+- The manifest `[lints]` table requires a toolchain generation that supports
+  it; verify the repo's minimum supported Rust version before recommending
+  it.
+- For repos below that floor, keep lint levels in CI flags and recommend the
+  manifest table as part of the upgrade path.
+
+## What Counts As Real Policy
+
+1. the discovered `[lints]`/`[workspace.lints]` tables and their levels
+2. `clippy.toml` settings
+3. CI lint invocations and deny levels
+4. inline lint-expectation or narrowly scoped allow attributes with reasons,
+   as bounded local exceptions
+
+## Starter Adoption (Reviewed Edit, Not A Script)
+
+The starter lives at `assets/lints-template/Cargo-lints.toml`. Its merge
+target (`Cargo.toml`) always already exists, so this skill intentionally
+ships no scaffolding script: adoption must stay a deliberate, reviewed edit.
+
+Adopt it only when:
+
+1. no explicit lint policy exists in manifests, `clippy.toml`, or CI, and
+2. the adopting repository wants this catalog's starter baseline
+
+Adoption steps:
+
+1. for workspaces, place the table contents under `[workspace.lints]` in the
+   root manifest and add `[lints] workspace = true` to member crates
+2. for single crates, place the contents under `[lints]` in `Cargo.toml`
+3. show the resulting diff to the user before finalizing
+4. run the repo's clippy command and review new findings together instead of
+   silencing them wholesale
+
+## Adaptation Points After Adoption
+
+1. tune lint levels to repo noise tolerance; promote to `deny` only where the
+   team agrees
+2. relax test-only ergonomics (for example unwrap-style lints) with scoped,
+   justified attributes rather than global allows
+3. wire the clippy command into the repo's task runner or CI so the policy is
+   actually enforced
+4. document the lint policy decision where the repo keeps its engineering
+   conventions

.agents/skills/ub-rust/references/repository-rust-workflows.md

@@ -0,0 +1,102 @@
+# Repository Rust Workflows
+
+Use this reference to resolve a repository's actual Rust toolchain, workspace,
+and validation truth before recommending commands or tooling.
+
+It should help the agent inspect local reality, not hardcode one repository's
+workflow into a distributable skill.
+
+## Toolchain and Workspace Baseline
+
+Inspect the target repository for:
+
+1. `edition` and `rust-version` in `Cargo.toml`, plus `rust-toolchain.toml`
+   channel pinning
+2. workspace layout: single crate, virtual workspace, member globs, and
+   workspace-inherited dependencies or lints
+3. whether the repo is an application, a library, a CLI tool, an FFI crate,
+   or a mixed workspace
+4. the active lint policy: `[lints]`/`[workspace.lints]` tables,
+   `clippy.toml`, `rustfmt.toml`, and CI lint flags
+5. feature flags and cfg matrices that change what compiles
+6. `build.rs` scripts, code generation, and vendored or patched dependencies
+7. `.cargo/config.toml` for aliases, target settings, and registry
+   configuration
+
+## Enforced Validation Baseline
+
+Treat the repository's wired checks as the real baseline.
+Inspect task runners, Makefiles, CI, and pre-commit hooks for the actual
+Rust-oriented gates.
+
+Common examples:
+
+1. `cargo fmt --check`
+2. `cargo clippy` with explicit deny/warn levels
+3. targeted or full `cargo test` commands, including doc tests
+4. `cargo deny check` or `cargo audit` supply-chain runs
+5. build matrix checks across targets, features, or toolchain versions
+6. MSRV verification jobs
+
+## Not Yet Repository-Wired
+
+Recommend extra tools only as explicit gaps when they are not already wired
+into the repository.
+
+Typical examples:
+
+1. clippy in CI
+2. an explicit `[lints]` policy
+3. cargo-deny or cargo-audit
+4. Miri for unsafe-heavy crates
+
+When advising users inside any repository:
+
+1. treat the detected edition and `rust-version` as the shipping constraint
+   even when official docs describe newer features
+2. recommend missing tools as improvements, not as if they were already part
+   of the enforced baseline
+3. keep guidance consistent with the repo's actual workload instead of
+   assuming a service-backend shape
+4. do not recommend syntax or standard library APIs above the crate's floor
+   as if they were currently shippable
+
+## Practical Command Patterns
+
+Use the command shape that matches the target repository's tooling.
+
+Recommended resolution order:
+
+1. a repo wrapper such as `task`, `make`, `just`, or a documented cargo alias
+2. direct cargo commands scoped to touched crates first
+   (`cargo check -p <crate>`, `cargo test -p <crate>`)
+3. lint and audit commands (`cargo clippy`, `cargo deny check`) only after
+   confirming they are installed or wired locally
+
+Scoping guidance:
+
+1. prefer `cargo check` for fast iteration before full builds
+2. run doc tests when public API docs changed
+3. run the full workspace only when failures indicate cross-crate impact
+4. respect feature matrices: test with the feature set CI actually uses
+
+## Starter Lint Policy
+
+This skill ships a reusable lint-table starter:
+
+1. `assets/lints-template/Cargo-lints.toml`
+
+It is merge material for `Cargo.toml`, applied as a reviewed edit. Use it only
+when a target repository wants this lint baseline and has no explicit lint
+policy yet. See `references/cargo-lints-resolution.md` for adoption steps.
+
+## Packaging and Release Guidance
+
+Because adopting repositories range from libraries to services to CLI tools:
+
+1. keep binary crates thin; put logic in library crates so it stays testable
+2. use workspace dependency inheritance to keep versions consistent
+3. for published crates, keep `rust-version` accurate and document the MSRV
+   policy
+4. align generated Rust with the active lint policy, including clippy levels
+   and rustfmt configuration