fix(thumbnail): [PKG-TOOL-THUMB-04] supply public types and installed module entries

refactor/changes/2026-09-13-PKG-TOOL-THUMB-04-public-types.md

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+# PKG-TOOL-THUMB-04 public types and installed entry checkpoint
+
+Task remains doing while THUMB-COMPAT-01's default policy is pending. Starts from
+15485b6420dece2b04503bd4fa99a9da0f9c8ba0. Public declarations and installed consumption
+are implemented; this does not declare package release or full refactor readiness.
+
+## Public contracts and distribution
+
+The missing d.ts entry is replaced with a CommonJS class/namespace declaration,
+paired d.cts/d.mts wrappers and type-only names. Root require/default keeps the
+direct constructor. Root import/module targets the actually generated .mjs, main
+is explicit, and the new legacy subpath includes old TS resolution. No .default
+self-alias is invented. Existing frozen dist files remain packed. The frozen
+.esm.js target was absent; fixing root import does not restore a nonexistent file.
+Historical 3.5.31 CSS disposition remains a 06 question under BASE-DIST-01.
+
+A files allowlist includes dist, declarations, README, architecture and full MIT
+notices while excluding implementation/config/dependencies. No new dependency,
+lockfile, runtime target, version or package-manager change is introduced.
+Known tuples, ctx, coordinates, partial options, lazy fields, returns and old
+method spellings are declared. Custom event callbacks infer application tuples
+without any. Error payloads are unknown because arbitrary throws produce numeric,
+object or absent message values; a new runtime test verifies delivery and identical
+Promise rejection, including primitive/null throws. Source changes since the prior
+checkpoint are erased types; all final built bundles are compared byte-for-byte.
+
+## Editor generator issue found and fixed
+
+Full build:ts exposed an existing regression: MediaBunny's auxiliary media.d.ts was
+globbed into an invalid standalone media global, while the proxy declaration kept
+an unresolved ./media re-export. Generation now selects package-named entries.
+Explicit local type re-exports require supplied complete matching type sources;
+missing/renamed/partial definitions fail rather than disappearing. Callable
+variables and CommonJS classes preserve namespaces. MediaBunny's source declarations
+are unchanged; its editor output now includes opt-in media types. Thumbnail's exact
+uppercase global is generated and added to the real docs library list.
+
+Tests reproduce the old missing-relative-type diagnostic, compile the new types
+with current/old TS and reject incomplete inputs. The real Monaco worker consumes
+core/Thumbnail/MediaBunny declarations, rejects invalid selector input, emits and
+runs the Thumbnail constructor, custom event and repeated native DOM cleanup.
+This is not a file extraction test.
+
+## Evidence and continuation
+
+The installed runner creates a fixture from frozen Git inputs and a candidate Yarn
+tarball. The former is explicitly not an original npm archive. Frozen require
+works, import reports ERR_MODULE_NOT_FOUND and strict compilers report missing
+entry/declarations. Candidate installation is outside the workspace, offline with
+an unchanged frozen lock and verification of every installed byte. Current/old TS,
+no-interop CJS, root/legacy runtime and complete notices are covered. Final evidence
+distinguishes exploratory and final packs after package documentation changes.
+
+The pending user question describes the incompatible defaults: published recovered
+3.5.31 delay/fixed height versus unpublished workspace 4.4.0 synchronous video and
+aspect-derived height. No answer is inferred from elapsed time and these defaults
+remain unchanged. Continue the chosen policy/regressions before closing 04.
+Inherited emitter event-name handling still needs behavior review; 05/06 retain
+full demo/core combinations and supported Safari/WebKit file extraction.
+
+Revert this checkpoint to undo declaration/entry/generator changes, then run normal
+builds. Preserve prior 03 lifecycle fixes and upstream attribution. No push, tag,
+npm publication or hosted CI result is claimed.