feat(typescript): add coverage-summary to the TypeScript bundle

Last language in the coverage-summary fan-out, after Elisp, Python, and Go. Same kernel: count every source file on disk that's absent from the coverage report as 0% and weight the project number by file, so an untested file stays visible instead of being averaged away.

The script at languages/typescript/claude/scripts/coverage-summary.js parses an Istanbul json-summary report (the coverage-summary.json that c8, Vitest, and Jest all emit), takes per-file statements covered over total, and reports a file-weighted number plus the missing files. It walks the source dir for .ts/.js, skipping test files, declarations, and node_modules. Node built-ins only, so it runs via node with no install, and it doesn't reimplement the per-file table nyc already prints.

Tests are black-box, run with node's own test runner: a temp tree plus a json-summary report, the script invoked via node, output asserted. They cover missing-file detection, all-tracked, test-file and node_modules exclusion, and the missing-report error. make test gained a node --test discovery path for languages/*/tests, guarded so environments without Node skip it cleanly. As with Python, the TypeScript bundle had no gitignore-add.txt, which would have left the script un-gitignored on install, so I added one.

This finishes the fan-out: coverage-summary now ships in all four bundles, each parsing its own tool's report behind the same file-weighted, missing-as-0% kernel. I proved the Go and TypeScript scripts by running them (Go against a live profile, TS against a synthetic report and the CLI). Python and TypeScript weren't run against a live coverage tool, since neither coverage.py nor nyc is installed here, so the first adopter of each should check against a real report.

1 files changed, 11 insertions, 2 deletions

diff --git a/todo.org b/todo.org
index b6f28b8..9594a87 100644
--- a/todo.org
+++ b/todo.org
@@ -1156,12 +1156,21 @@ Reference (dotemacs): =scripts/coverage-summary.el=, =modules/coverage-core.el=,
 
 Origin: handoff from the .emacs.d session, 2026-05-25.
 
-** TODO [#C] Fan out coverage-summary to the TypeScript bundle :feature:
+** DONE [#C] Fan out coverage-summary across all language bundles :feature:
+CLOSED: [2026-05-31 Sun]
 :PROPERTIES:
 :CREATED: [2026-05-31 Sun]
 :END:
 
-The Elisp pilot proved the pattern; Python and Go followed (all three DONE above). The plumbing is generic: =install-lang.sh= seeds the fragment, and =make test= now discovers ERT (=test-*.el=), pytest (=test_*.py=), and =go test= (=*_test.go=) under =languages/*/tests/=. TypeScript is the last one.
+Done 2026-05-31: coverage-summary now ships in all four bundles. Elisp pilot, then Python, Go, and TypeScript. Each parses its tool's report (SimpleCov / coverage.py JSON / Go cover.out / Istanbul json-summary), counts on-disk source files absent from the report as 0%, and file-weights the project number. The plumbing proved generic: =install-lang.sh= seeds the project-owned =coverage-makefile.txt= and ships the script into the gitignored =.claude/scripts/=; =make test= discovers ERT (=test-*.el=), pytest (=test_*.py=), =go test= (=*_test.go=), and =node --test= (=*.test.js=) under =languages/*/tests/=, each guarded on its toolchain. TypeScript and Go scripts were dogfooded (Go against a live profile, TS against the CLI); Python and TS weren't run against a live coverage tool (coverage.py / nyc not installed) — proven against faithful fixtures matching each tool's stable schema.
+
+Remaining follow-ups (not blockers):
+- Go is a coverage-only slice — =languages/go/= has no rule file, so =sync-language-bundle.sh= can't fingerprint it and won't sync-maintain the script. Build out the real Go bundle (=go.md= / =go-testing.md= + =CLAUDE.md=) to close that.
+- First real adopters of the Python and TS scripts should sanity-check against a live =coverage json= / nyc =coverage-summary.json= run.
+
+Original notes retained below for the next person.
+
+The Elisp pilot proved the pattern; Python and Go followed. The plumbing is generic: =install-lang.sh= seeds the fragment, and =make test= now discovers ERT (=test-*.el=), pytest (=test_*.py=), and =go test= (=*_test.go=) under =languages/*/tests/=. TypeScript is the last one.
 
 - TypeScript/JS: nyc/Istanbul =coverage-final.json= / =coverage-summary.json=. Same kernel: file-weighted project number, on-disk =*.ts=/=*.js= absent from the report counted as 0%. nyc prints its own table, so the script focuses on the missing-file list and the number. Needs a vitest/jest (or =node --test=) discovery path in =make test=, mirroring the go-test block.