Releases 2.15.0

[johnnyt]

Release prep for statifier 2.15.0. The prep only: the desk merges, tags v2.15.0 at the merge SHA and pushes the tag; release.yml publishes on the tag push.

The version and why

2.15.0, a minor. The release adds the :function_providers and :function_names options (ADR-0078), and Statifier.Compiler.Error's closed reason union, t:reason/0, grows by {:unknown_function, name, source}: a chart whose expressions call a function that is not In, a predicator builtin or a declared host function is refused at compile time, where it compiled and raised error.execution at every evaluation of the call. The check stays at compile time as built, ruled by the operator, 2026-10-12, who named this release the same day. The fragment carries the refusal under Changed; none is a Removed or Deprecated entry.

The closed-set answer

Read from git diff v2.14.0..origin/main -- lib and the fragment, for a new member of a closed vocabulary a host pattern-matches:

• Statifier.Compiler.Error t:reason/0 gains {:unknown_function, name :: String.t(), source :: String.t()}. This is the one new member of a closed union.
• Statifier.Session.start_link/2 can answer {:error, {:function_providers, reason}} for a provider list that does not resolve, before it starts anything.
• Statifier.MachineState gains a functions field and put_function_providers/2; Statifier.Position drops the field as it drops invoke_types and send_types.
• Statifier.Chart.from_binary/1 answers :not_a_statifier_blob for a blob carrying :function_providers or a :function_names that is not a list of strings, an existing answer.
• A recording with no provider is byte-identical to one written before this change, so the recording format version does not move.

No runtime dependency requirement or lock line moves since v2.14.0, and the conformance corpus does not change.

Fragments promoted

Into ## [2.15.0] 2026-10-12, each bullet byte for byte, then deleted (changelog.d/README.md stays):

• Added and Changed: changelog.d/st-g648.md

The heading carries no dash and the file gains no link reference (.claude/wurk/release.md step B). The lead paragraph names the new option and the compile refusal; it makes no "registers nothing" claim, as no send type changes.

The upgrading page

A separate commit, as docs/upgrading.md is outside the release commit's files. The title and the intro's range move to 2.15.0, and a new intro sentence names the hosts 2.15.0's changed answer reaches. The 2.15.0 section, written from the fragment's host-facing sentences:

• must change: only where the compile refusal of an undeclared function reaches a host (register it with :function_providers, or declare its name with :function_names; add a clause for the new reason where the compiler's reasons are matched exhaustively). A ~> 2.14 requirement already accepts 2.15.0.
• may start: registering host functions, with the purity contract, the resume and replay re-stamp, and the note that a child started for an <invoke> does not inherit the list. Requires ~> 2.15.
• the corpus: unchanged.

The commits

1. Carries the upgrading page to 2.15.0 (above).
2. Releases 2.15.0: exactly .claude/wurk/release.md's files, mix.exs @version "2.15.0", the README pin {:statifier, "~> 2.15"}, the CHANGELOG.md section and the deleted fragment. Committed on the staged tree the full mix quality and mix quality --profile merge ran green on, with no change between the green runs and the commit, the repository's gate lock and a machine slot held across both runs and the commit.
3. Addresses review of the 2.15.0 upgrading page (the review round below); documentation only.

Gate

Full mix quality green and attested on the final tree (3,329 of 3,329 tests, 96.3% coverage, Dialyzer clean, regression ratchet and conformance corpus passed, README stage green), and mix quality --profile merge green; its ADR judge skipped, as no file in this diff is in a judged scope. Earlier runs on the same tree, on a heavily loaded machine, failed only on Basic HTTP timing cases (the regression ratchet's optional Basic HTTP cases and Statifier.Send.BasicHTTPSessionTest's delayed-send cases), which pass when run alone; this diff touches no code.

Review round: wurk-diff-critic, one fresh round over origin/main...f7525a3, returned 3 findings (none must-fix). All 3 fixed in acea473, on the upgrading page only: the intro now says why the compile refusal is listed under Changed and not as a Breaking entry (it refuses only a chart whose call raised error.execution whenever it was evaluated; the fragment bullet is carried byte for byte and minor follows the 2.14.0 precedent); the must-change bullet names a chart stored before 2.15.0 and recompiled under it; and the may-start steps say that compile/2 and MachineState.new/2 raise ArgumentError for a bad provider list and that a chart given as <invoke> content cannot call a host function. Head reviewed: f7525a3; head after fixes: acea473. The full gate and mix quality --profile merge ran green again on acea473.

After the merge

The desk merges, pulls main, tags v2.15.0 at the merge SHA and pushes the tag; release.yml publishes on that tag push. Nothing in this PR tags or publishes.