fix: pin rendered numbers to one locale so graft can read its own savings footer (#338)

[Ercaner1988]

Fixes #338.

savingsLine() wrote the footer with the machine's locale; sumSavingsFooters() read it back with ([\d,]+). On a machine that groups thousands with anything but a comma, graft parsed its own footer as the first group — 1.990 came back as 1, and every savings total downstream went with it.

The change

One formatter, pinned, next to the reader that has to cope with its output:

export function groupDigits(n: number): string {
  return n.toLocaleString('en-US');
}

Five call sites now go through it. Three of them write the [graft] tokens saved ≈ N line that sumSavingsFooters parses — context/savings.ts, ask/ask.ts, claude/format.ts, each with its own wording of the same footer — and the other two are the displays that sit beside it, the statusline's ~N tok saved and graft stats.

I pinned the two display sites as well, and that is the one judgement call in here worth flagging. They are never parsed, so locale-aware would be defensible — but graft's output is English throughout, a statusline reading 1.990 directly above a footer reading 1,990 would be its own small bug, and src/cli-epilogue.ts:50 already pins the same way (nodes.toLocaleString("en-US")), which is where I took the precedent from. I left that line alone rather than reach across from an init banner into the savings module; say the word if you would rather have it routed through the same helper, or would rather keep the two displays locale-aware and pin only the parsed line.

The reader is untouched. Widening it instead was the option I would not take: 1.990 is a valid en-US decimal, so a reader that strips separators is guessing, and it would have to know about U+202F and U+00A0 too.

Tests

test/savings-locale.test.ts. A process cannot change its own ambient locale — Node reads it from the environment on posix and from the OS on Windows — so the test moves the default instead: toLocaleString() with no argument answers as a .-grouping locale would, while calls that name a locale explicitly are left alone. That is exactly the difference the fix turns on, so the test fails without it and passes with it on an en-US runner too, which is the property CI was missing. It asserts the stand-in actually changes an unqualified call first, so the rest cannot pass for the wrong reason.

The third test renders the footer through formatAsk(). ask/ask.ts has its own wording of the parsed line, and no test rendered it at all — your blast-radius bot flagged it ("no test reaches Ask Token Savings"), and it was right: reverting just that file to toLocaleString() brought #338 back for every graft ask with the rest of the suite still green. Now it fails.

All three fail on upstream/main. The first two:

✖ #338: the savings footer round-trips on a machine that is not en-US
  actual: '[graft] tokens saved ≈ 1.990 (100%) — this output ≈ 10 tok …'
  expected: /tokens saved ≈ 1,990/
✖ #338: what graft displays groups the same way as what it parses
  actual: '… tokens saved:  ~12.345'

Verified

The eight tests that fail on upstream/main on this machine — the ones I mentioned in #337 — are the eight this fixes. npm test on a tr-TR box:

	tests	pass	fail
upstream/main	1220	1207	8
this branch	1223	1218	0

(5 skipped either way.)

Seven of the eight were assertions that assumed ,, and they now hold because the output does. The eighth, tool-savings counts a REAL savings line, was the round trip itself failing 1 !== 1990 — it is the test that should have caught this and could not, because the footer it feeds is rendered in the runner's own locale. It passes here now, which is the end-to-end proof: a real savingsLine() through the real hook, on a machine that groups with ., recording 1990.

One test needed the same treatment as the source. test/savings.test.ts:52 built its expected value with (…).toLocaleString(), so once the footer was pinned it asserted 1.990 against a footer saying 1,990 — the mirror image of the bug. It now goes through groupDigits too.

Re-measured against de8456e (0.18.0) after rebasing onto it: same 8, same numbers.

No CHANGELOG entry

I dropped the one I had. 0.18.0 is already released, so there is no unreleased section to add to, and de8456e shows the release commit is what writes them. Happy to add a bullet wherever you want it.

Environment: Node v24.16.0, Windows 11 x64, OS locale tr-TR.

🤖 Generated with Claude Code

[trailhq-graft]

🌱 graft blast radius

3 areas changed → 5 areas can be affected. 10 dependent symbols, depth 2.
Tests: no test reaches Ask Savings Display; 2 areas updated their tests.
Tag: @shhdwi — 7 of 8 areas · @anirudhkumar-nanonets — 8 of 8 areas · @afeddersen — Token Savings Calculation

flowchart TB
  A0(("Workspace Federation<br/>4 symbols"))
  A1(("MCP Tool Invocation<br/>2 symbols"))
  A2(("Claude UI Integration<br/>2 symbols"))
  A3(("CLI Entry Point<br/>1 symbol"))
  A4(("Grep Search Formatting<br/>1 symbol"))
  classDef reached fill:#D9EDF3,stroke:#3AA7C9,stroke-width:1.5px,color:#0E313C;
  class A0,A1,A2,A3,A4 reached;

Loading

Can be affected	Symbols	Nearest hop	Reached from
Workspace Federation	4	src/graph/map.ts:L325-L350 formatRepoMap — calls, depth 2	Ask Savings Display, Token Savings Calculation
MCP Tool Invocation	2	src/mcp/tools.ts:L247-L329 callSingleTool — calls, depth 2	Ask Savings Display, Token Savings Calculation
Claude UI Integration	2	src/claude/statusline.ts:L24-L35 main — calls, depth 1	Session Metrics Formatting, Token Savings Calculation
CLI Entry Point	1	src/cli.ts:L1-L1407 cli.ts — calls, depth 1	Ask Savings Display, Session Metrics Formatting +1
Grep Search Formatting	1	src/search/grep-cli.ts:L54-L63 formatGrepResult — calls, depth 2	Token Savings Calculation

Who knows this code — 3 people across 8 areas

Area	Who knows it
Token Savings Calculation · changed	@anirudhkumar-nanonets — 4 commits, last 10d ago · @afeddersen — 1 commit, last 12d ago
Ask Savings Display · changed	@shhdwi — 16 commits, last 1mo ago · @anirudhkumar-nanonets — 11 commits, last 2d ago
Session Metrics Formatting · changed	@shhdwi — 10 commits, last 2mo ago · @anirudhkumar-nanonets — 6 commits, last 10d ago
Workspace Federation · affected	@shhdwi — 14 commits, last 30d ago · @anirudhkumar-nanonets — 8 commits, last 19d ago
MCP Tool Invocation · affected	@shhdwi — 14 commits, last 30d ago · @anirudhkumar-nanonets — 7 commits, last 10d ago
Claude UI Integration · affected	@shhdwi — 13 commits, last 30d ago · @anirudhkumar-nanonets — 9 commits, last 10d ago
CLI Entry Point · affected	@anirudhkumar-nanonets — 39 commits, last 2d ago · @shhdwi — 23 commits, last 30d ago
Grep Search Formatting · affected	@anirudhkumar-nanonets — 4 commits, last 1mo ago · @shhdwi — 3 commits, last 2mo ago

Ownership is git history over each area's own files, weighted towards recent work (120-day half-life). Merge commits and bots are dropped, and you are dropped from your own PR. A name with no @ has no GitHub handle in its commit email — tag them by hand, or add a .mailmap entry. A suggestion from history, not a CODEOWNERS rule.

All 10 dependent symbols, grouped by area

Workspace Federation — 4 symbols in 4 files

• src/graph/map.ts:L325-L350 — formatRepoMap (calls, depth 2)
• src/graph/traverse-cli.ts:L166-L242 — runCallersCommand (calls, depth 2)
  194: // `all` (aka full/max) = the whole transitive closure: walk until no new
• src/graph/workspace-cli.ts:L88-L97 — runWorkspaceAsk (calls, depth 2)
• src/graph/workspace.ts:L659-L695 — federateCallers (calls, depth 2)

MCP Tool Invocation — 2 symbols in 1 file

• src/mcp/tools.ts:L247-L329 — callSingleTool (calls, depth 2)
• src/mcp/tools.ts:L153-L199 — callWorkspaceTool (calls, depth 2)

Claude UI Integration — 2 symbols in 2 files

• src/claude/statusline.ts:L24-L35 — main (calls, depth 1)
  34: process.stdout.write(renderStatusline(stats, session, { ctxPct }).join('\n'));
• src/claude/hooks.ts:L394-L462 — main (calls, depth 2)
  421: if (event === 'tool-savings') { handleToolUse(input, dir); return; }

CLI Entry Point — 1 symbol in 1 file

• src/cli.ts:L1-L1407 — cli.ts (calls, depth 1)
  48: import { latestSession, formatSessionStats, sessionInputRate } from "./claude/session-metrics.js";

Grep Search Formatting — 1 symbol in 1 file

• src/search/grep-cli.ts:L54-L63 — formatGrepResult (calls, depth 2)

Test signal per changed area — 2 ✓ · 1 ✗

Reached = a node under a test path has a resolved edge into the changed symbol. It undercounts anything called indirectly — through a CLI, a spawned process or a dynamic import — so read a low ratio as “look here”, never as a coverage gate.

• ✓ Token Savings Calculation — 2 of 2 reached · 2 test files changed here: test/savings-locale.test.ts, test/savings.test.ts
• ✗ Ask Savings Display — 0 of 1 reached · no test file reaches it
  • not reached: askSavingsLine
• ✓ Session Metrics Formatting — 3 of 3 reached · 1 test file changed here: test/savings-locale.test.ts

8 test suites also reference this code

8 symbols, kept out of the diagram and the table so they cannot crowd out the areas a reviewer has to look at.

• test/ask-fusion.test.ts
• test/ask.test.ts
• test/claude-format.test.ts
• test/claude-hooks.test.ts
• test/claude-statusline.test.ts
• test/regression-single-repo.test.ts
• test/session-metrics.test.ts
• test/workspace.test.ts

_{graft blast · origin/main...HEAD · depth 2 · 7 changed files}

Open the interactive graph → — click an area to see its dependent symbols at file:line.