feat(tui): generate word-navigation napi bindings via fluessig

[zmaril]

Stacked on #307 (module 4, tui utils/width). Base branch is napi-fluessig/tui-utils, so this diff is just the two word-navigation.ts exports.

Before / After

The packages/tui/src/word-navigation.ts layer — findWordBackward and findWordForward — used to be hand-written #[napi] free functions in lib.rs. After this change they are generated from the fluessig api schema through crate::generated + the core_impl seam, routing into pidgin_tui::word_navigation's default-segmenter path.

The JS surface is unchanged: every symbol's .d.ts block (JSDoc included) and .js glue is byte-identical to the pre-swap origin/main baseline, and the dedicated conformance oracle (packages/tui/test/word-navigation.test.ts) passes 19/19.

Both ops are (text: string, cursor: int32) -> int32. Cursors are UTF-16 string indices, authored in the schema as int32 (fluessig → Rust i32 → JS number) and widened to the engine's usize at the seam. The pre-swap exports used u32 (also number in .d.ts), so int32 reproduces the JS-visible surface byte-for-byte. The three shim-delegated "atomic segments" tests (which fall back to pi's original when a JS options.segment/options.isAtomicSegment callback is supplied) continue to pass unchanged.

How

• Schema: appended the 2 ops to crates/pidgin-napi/schema/api.json (shape: unary, infallible: true, readonly: true, bindings.node.name = exact JS export name). Params text: string, cursor: int32; return int32. catalog.json unchanged (no new DTOs).
• Seam: added 2 delegations to impl PidginCore for PidginImpl in src/core_impl.rs, each routing to the same pidgin_tui::word_navigation fn the hand-written export called. The i32 cursor param/return is widened to the engine's usize, matching the pre-swap as usize/as u32 casts.
• Regen: reran crates/pidgin-napi/regen.sh (fluessig pinned at 1fed77a) to regenerate src/generated.rs. Deleted the 2 hand-written exports from src/lib.rs.

Verification

• Per-symbol .d.ts + .js byte-diff vs origin/main baseline: both symbols IDENTICAL (JSDoc blocks and module.exports glue); the two symbols moved into the generated block right after extractSegments, the same mechanical reorder as modules 2-4.
• cargo build -p pidgin-napi, cargo fmt --all --check, cargo clippy -p pidgin-napi --all-targets -- -D warnings: clean.
• codespell on touched files: 0 findings.
• straitjacket v0.2.3 whole-tree scan of git archive HEAD: 877 files, 0 errors (1 pre-existing conformance/STEWARD.md slop-prose warning).
• packages/tui/test/word-navigation.test.ts (19/19) against the locally-built addon: all pass.

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🤖 Generated with Claude Code

https://claude.ai/code/session_017xL2W7dkhPsTSRuXQNCDeY

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Generated by Claude Code

[github-actions]

Conformance smoke: agent + ai + tui

• pi_sha: 3da591ab74ab9ab407e72ed882600b2c851fae21
• manifest_native_modules: 54

Headline is rust-backed: passing cases in files whose module-under-test is a native (Rust addon) module. Raw all-pass is shown secondary — it is inflated by unflipped TypeScript that passes without touching any Rust.

Package	rust-backed	Native modules	raw pass (secondary)	Failing	Skipped
agent	73/180 (40.6%)	7	180/180	0	0
ai	81/1296 (6.3%)	11	553/1296	3	740
tui	375/678 (55.3%)	14	678/678	0	0
smoke total	529/2154 (24.6%)	32	1411/2154	3	740

agent: 73/180 (40.6%) · ai: 81/1296 (6.3%) · tui: 375/678 (55.3%)

rust-backed = passing / total tests run, per the manifest's per-native-row tests lists. The Native modules column counts modules served by the Rust addon. This is the agent+ai+tui smoke subset; the full baseline lives in committed conformance.json.

Attribution

A pi test file is rust-backed iff the module it primarily exercises — its module-under-test — is status=native in conformance/manifest.json. A package's rust-backed count is the passing cases in its rust-backed files. Transitive or infrastructure use does not count (e.g. ~30 ai files construct the native faux provider but test other things — only faux-provider.test.ts, whose subject is faux, counts). A file that substantially tests both a native and an original module is excluded rather than counted, so the number under-reports rather than over-claims.

Per-file decisions (from each native manifest row's tests list):

Native module	Test file	Decision
ai/api/anthropic-messages.ts	test/anthropic-sse-parsing.test.ts	counted
ai/providers/faux.ts	test/faux-provider.test.ts	counted
coding-agent/utils/ansi.ts	test/ansi-utils.test.ts	counted
coding-agent/utils/changelog.ts	test/changelog.test.ts	counted
coding-agent/utils/git.ts	test/git-ssh-url.test.ts	counted
coding-agent/core/tools/path-utils.ts	test/path-utils.test.ts	counted
tui/keys.ts	test/keys.test.ts	counted
tui/utils.ts	test/truncate-to-width.test.ts, test/regression-regional-indicator-width.test.ts	counted
coding-agent/utils/mime.ts	test/image-process.test.ts	mixed — excluded (2 of 3 cases test processImage/original)
coding-agent/utils/version-check.ts	test/version-check.test.ts	mixed — excluded (fetch cases mock the original; not separable per-file)
coding-agent/core/export-html/ansi-to-html.ts	test/export-html-whitespace.test.ts	mixed — excluded (asset-grep + tool-renderer/original dominate)
coding-agent/core/tools/truncate.ts	—	no dedicated test (exercised via tools.test.ts, subject is the read/edit factory/original)
coding-agent/core/tools/edit-diff.ts	—	no dedicated test (edit-tool tests' subject is the edit tool/original)

CLI conformance (black-box, against the pidgin binary)

• CLI conformance: 15/15 pass against target/release/pidgin (pass delta ±0, fail delta ±0).

File	Passing	Failing	Skipped
packages/coding-agent/test/session-file-invalid.test.ts	1	0	0
packages/coding-agent/test/session-id-readonly.test.ts	7	0	0
packages/coding-agent/test/startup-session-name.test.ts	2	0	0
packages/coding-agent/test/stdout-cleanliness.test.ts	5	0	0

The four repointed coding-agent CLI test files spawn the compiled pidgin binary via $PIDGIN_BIN instead of pi's own cli.ts. This is a separate signal from the module smoke table and is never folded into the per-package Native count.