greptile P2 nitpick: the previous commit's docblock said "on every
PreToolUse hook" but the module header (and the actual hook wiring
in `hooks/hooks.json`) identifies this script as a PostToolUse
hook — it runs *after* each tool invocation to update the running
session aggregate. One-word typo, no behavior change.
coderabbitai flagged: the two `catch` blocks in `readSessionCost`
silently swallowed every failure mode. A malformed `costs.jsonl`
row, a permission error opening the file, or any other unexpected
I/O failure would silently return zero cost — masking real
problems and feeding stale or zero numbers into
`ecc-context-monitor.js` (which then injects them as
`additionalContext` into the live model turn).
Fix two things, both fail-open-preserving:
1. **Inner JSON.parse catch** — count malformed lines and write
one aggregated breadcrumb per call:
[ecc-metrics-bridge] skipped N malformed line(s) in <path>
Aggregating (rather than per-line) keeps a log-flooded
`costs.jsonl` diagnosable without overwhelming stderr.
2. **Outer fs.readFileSync catch** — write a breadcrumb on real
errors, but stay silent on `ENOENT`. The "no costs.jsonl yet"
case is genuinely normal (no Stop event has fired this session)
and producing noise on every PreToolUse before the first Stop
would be reviewer-visible spam. All other error codes
(`EACCES`, `EISDIR`, `EMFILE`, …) get:
[ecc-metrics-bridge] failing open after <name> reading <path>: <msg>
In both cases the function still returns the zero-cost fallback
so the bridge never breaks tool execution — only the
diagnosability changes.
Two new regression tests in
`tests/hooks/ecc-metrics-bridge.test.js`:
✓ readSessionCost writes a stderr breadcrumb when malformed
lines are skipped — feeds 4 rows (2 valid, 2 malformed),
asserts the last valid row still wins AND captured stderr
contains "skipped 2 malformed line(s)".
✓ readSessionCost stays silent when costs.jsonl does not exist
(ENOENT) — uses a fresh tmp HOME with no metrics dir, asserts
zero return AND empty stderr.
Test count: 16 → 18; `npm test` green; `yarn lint` clean.
`readSessionCost` read only the trailing 8 KiB of
`~/.claude/metrics/costs.jsonl` to "avoid scanning entire file".
That ceiling is the opposite-sign sibling of the double-count bug
fixed in the previous commit: once a session's most recent
cumulative row gets pushed past the 8 KiB window by newer rows
from other sessions, the bridge silently reports `totalCost: 0`,
`totalIn: 0`, `totalOut: 0` for that session — same false signal
to `ecc-context-monitor.js`, same wrong number injected into the
live model turn as `additionalContext`.
`cost-tracker.js` has no rotation policy, so on any non-trivial
workstation costs.jsonl grows past 8 KiB within minutes of normal
use. For users who keep multiple concurrent sessions, this means
the second-and-later sessions silently report zero almost
immediately.
Reproduced before this commit:
$ HOME=/tmp/eccc node -e '
const fs = require("fs");
const m = require("./scripts/hooks/ecc-metrics-bridge.js");
// S1 row at file start, then 200 rows of OTHER-session noise (~16 KiB).
// S1 is the row we want, but it sits past the 8 KiB tail.
const s1 = `{"session_id":"S1","estimated_cost_usd":0.5,"input_tokens":500,"output_tokens":250}`;
const other = `{"session_id":"OTHER","estimated_cost_usd":1,"input_tokens":100,"output_tokens":50}`;
fs.mkdirSync("/tmp/eccc/.claude/metrics", { recursive: true });
fs.writeFileSync("/tmp/eccc/.claude/metrics/costs.jsonl",
[s1, ...Array(200).fill(other)].join("\\n") + "\\n");
console.log(JSON.stringify(m.readSessionCost("S1")));'
{"totalCost":0,"totalIn":0,"totalOut":0}
Expected: `{"totalCost":0.5, "totalIn":500, "totalOut":250}` (the
S1 row that exists in the file).
Actual: zero — the row is past the 8 KiB tail.
Fix: drop the `fs.openSync` + bounded `fs.readSync` + position
arithmetic in favour of `fs.readFileSync(costsPath, 'utf8')` and
iterate every line. Each row is ~150 bytes; even 100k rows is
~15 MB and a single sync read on PreToolUse is in the low ms.
If file rotation lands in `cost-tracker.js` later, this scan
becomes proportionally cheaper.
After this commit the reproduction above returns
`{"totalCost":0.5, "totalIn":500, "totalOut":250}`.
Regression test in `tests/hooks/ecc-metrics-bridge.test.js`:
`readSessionCost finds session row beyond the old 8 KiB tail
boundary`. The test asserts the costs.jsonl fixture is > 8 KiB
before reading so any reintroduction of a bounded tail would
re-fail the test (i.e. the assertion is the contract, not the
specific number 8192).
Together with the previous commit, both directions of the
metrics-bridge cost-reporting bug are closed.
`ecc-metrics-bridge.js#readSessionCost` summed the
`estimated_cost_usd`, `input_tokens`, and `output_tokens` of
every matching row in `~/.claude/metrics/costs.jsonl`. That breaks
the documented contract of `scripts/hooks/cost-tracker.js`, which
explicitly states (in its module docblock):
Cumulative behavior: Stop fires per assistant response, not
per session. Each row therefore represents the cumulative
session total up to that point. To get per-session cost, take
the last row per session_id.
Summing N cumulative rows over-counts by roughly (N+1)/2 ×. For a
session with 3 rows at 0.01, 0.02, 0.03 USD (true running total
0.03), the bridge today reports 0.06 USD. The over-counted value
feeds `ecc-context-monitor.js`, which then trips its
COST_NOTICE_USD / COST_WARNING_USD / COST_CRITICAL_USD thresholds
on phantom spend AND injects the inflated number as
`additionalContext` into the live model turn — so the agent
itself is told a wrong cost.
Reproduced on `main` before this commit:
$ cat > /tmp/eccc/.claude/metrics/costs.jsonl <<EOF
{"session_id":"S1","estimated_cost_usd":0.01,"input_tokens":333,"output_tokens":166}
{"session_id":"S1","estimated_cost_usd":0.02,"input_tokens":666,"output_tokens":333}
{"session_id":"S1","estimated_cost_usd":0.03,"input_tokens":1000,"output_tokens":500}
EOF
$ HOME=/tmp/eccc node -e 'const m = require("./scripts/hooks/ecc-metrics-bridge.js"); \
console.log(JSON.stringify(m.readSessionCost("S1")))'
{"totalCost":0.06,"totalIn":1999,"totalOut":999}
Expected: `{"totalCost":0.03,"totalIn":1000,"totalOut":500}` (the
last cumulative row).
Actual: 2× over-count.
Fix: replace `+=` with `=` in the matching branch so the assigned
values reflect the most recent row encountered. The iteration
order is file order, which is also event time order, so the last
assignment wins — exactly the contract cost-tracker writes
against.
After this commit the reproduction above returns
`{"totalCost":0.03,"totalIn":1000,"totalOut":500}`.
Regression test in `tests/hooks/ecc-metrics-bridge.test.js`:
`readSessionCost returns the LAST cumulative row, not the sum
(cost-tracker contract)`. The existing
`readSessionCost does not include unrelated default-session rows`
test happened to pass even with the bug because it only had one
target-session row — single-row sessions are coincidentally
correct under both formulas. The new test uses three rows so the
two formulas diverge.
A second issue in the same function — the 8 KiB tail-only read
silently drops older rows once a session's recent cumulative
totals scroll past that window — is fixed in the next commit.
Adds docs/th/README.md with a concise onboarding-style Thai
translation mirroring the docs/vi-VN format. Updates the language
switchers in the English, Simplified Chinese, Traditional Chinese,
Japanese, Korean, Portuguese (BR), Russian, Turkish, Vietnamese,
and Simplified Chinese docs READMEs to link to the new Thai page.
The English README remains the canonical source of truth; the Thai
page links back to it for full content.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
