📊 Mutation testing — weekly baseline

[github-actions]

Score: 67.2% (↑ +0.1 vs prior)

Per-shard breakdown

Shard	Score	Killed	Survived	No cov	Timeout	Errors	Total
mutation-report-db	—	—	—	—	—	—	(missing)
hardware-lib	67.5%	1619	591	180	7	969	3391
homekit	62.6%	290	164	9	0	201	689
hooks	73.5%	886	296	23	1	483	1707
server	59.5%	1421	595	371	2	1682	5117
services-scheduler	73.2%	561	186	16	3	251	1019
streaming	73.1%	890	252	63	13	411	1638

• HTML reports: attached as mutation-report-<shard> artifacts on run 29145443368.
• Hit list artifact: mutation-hitlist on the same run.
• Last updated: 2026-07-11T09:31:49.682Z (commit cf895d7, trigger: schedule).

This issue is updated automatically by .github/workflows/mutation.yml on each scheduled / manual mutation run. Do not edit the body — it will be overwritten. Comment freely to track work on surviving mutants.

---

Mutation testing — hit list

Score: 67.2% · Total mutants: 13561

Status	Count
Killed	5667
Survived	2084
NoCoverage	662
Timeout	26
CompileError	3996
RuntimeError	1
Ignored	1125

Surviving mutants by file (80 files, top 50 mutants shown)

For each entry below: the mutator type tells you what Stryker changed, the snippet shows where, and "expected test" is the most likely location to add a killing assertion. A killing test must fail when the mutation is applied.

src/streaming/piezoStream.ts — 151 surviving

Expected test file: src/streaming/tests/piezoStream.test.ts

LogicalOperator at line 47

    46 | 
>   47 | const WS_PORT = Number(process.env.PIEZO_WS_PORT ?? 3001)
    48 | const RAW_DATA_DIR = process.env.RAW_DATA_DIR ?? '/persistent'

+ (mutation): process.env.PIEZO_WS_PORT && 3001

StringLiteral at line 48

    47 | const WS_PORT = Number(process.env.PIEZO_WS_PORT ?? 3001)
>   48 | const RAW_DATA_DIR = process.env.RAW_DATA_DIR ?? '/persistent'
    49 | // Fallback subdirectory probed when RAW_DATA_DIR holds no usable .RAW files.

+ (mutation): ""

ArithmeticOperator at line 57

    56 | // index stays bounded on long-running streams (24h at 50fps was ~70MB).
>   57 | const FRAME_INDEX_RETENTION_S = SEEK_MAX_DURATION_S + 10
    58 | // Drop outbound frames for a client whose send buffer exceeds this many bytes.

+ (mutation): SEEK_MAX_DURATION_S - 10

ArithmeticOperator at line 60

    59 | // Prevents a slow/stalled client from pinning unbounded server memory.
>   60 | const MAX_BUFFERED_BYTES = 1024 * 1024 // 1 MB
    61 | // Cap inbound client messages. All client→server messages are tiny JSON

+ (mutation): 1024 / 1024

ObjectLiteral at line 317

   316 | 
>  317 | const cborDecoder = new Decoder({ mapsAsObjects: true, useRecords: false })
   318 | 

+ (mutation): {}

BooleanLiteral at line 317

   316 | 
>  317 | const cborDecoder = new Decoder({ mapsAsObjects: true, useRecords: false })
   318 | 

+ (mutation): false

BooleanLiteral at line 317

   316 | 
>  317 | const cborDecoder = new Decoder({ mapsAsObjects: true, useRecords: false })
   318 | 

+ (mutation): true

StringLiteral at line 52

    51 | // (and the SEQNO.RAW tmpfs symlink) sits at the /persistent root.
>   52 | const RAW_DATA_FALLBACK_SUBDIR = 'biometrics'
    53 | const FILE_POLL_INTERVAL_MS = 10 // match Python's 10 ms poll for new data

+ (mutation): ""

ConditionalExpression at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): true

LogicalOperator at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): frameIndex.length > 0 || frameIndex[0].ts < cutoff

ConditionalExpression at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): true

EqualityOperator at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): frameIndex.length >= 0

ConditionalExpression at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): true

EqualityOperator at line 127

   126 |   // slice is correct. Batch the splice to avoid O(n) shift per push.
>  127 |   if (frameIndex.length > 0 && frameIndex[0].ts < cutoff) {
   128 |     let drop = 0

+ (mutation): frameIndex[0].ts <= cutoff

ConditionalExpression at line 129

   128 |     let drop = 0
>  129 |     while (drop < frameIndex.length && frameIndex[drop].ts < cutoff) drop += 1
   130 |     if (drop > 0) frameIndex.splice(0, drop)

+ (mutation): true

EqualityOperator at line 129

   128 |     let drop = 0
>  129 |     while (drop < frameIndex.length && frameIndex[drop].ts < cutoff) drop += 1
   130 |     if (drop > 0) frameIndex.splice(0, drop)

+ (mutation): drop <= frameIndex.length

EqualityOperator at line 129

   128 |     let drop = 0
>  129 |     while (drop < frameIndex.length && frameIndex[drop].ts < cutoff) drop += 1
   130 |     if (drop > 0) frameIndex.splice(0, drop)

+ (mutation): frameIndex[drop].ts <= cutoff

ConditionalExpression at line 130

   129 |     while (drop < frameIndex.length && frameIndex[drop].ts < cutoff) drop += 1
>  130 |     if (drop > 0) frameIndex.splice(0, drop)
   131 |   }

+ (mutation): true

EqualityOperator at line 130

   129 |     while (drop < frameIndex.length && frameIndex[drop].ts < cutoff) drop += 1
>  130 |     if (drop > 0) frameIndex.splice(0, drop)
   131 |   }

+ (mutation): drop >= 0

StringLiteral at line 154

   153 |   function need(n: number): void {
>  154 |     if (pos + n > end) throw new RangeError('Incomplete record')
   155 |   }

+ (mutation): ""

ConditionalExpression at line 159

   158 |   need(1)
>  159 |   if (buf[pos] !== 0xa2) {
   160 |     throw new Error(`Expected outer map 0xa2, got 0x${buf[pos].toString(16)}`)

+ (mutation): false

BlockStatement at line 159

   158 |   need(1)
>  159 |   if (buf[pos] !== 0xa2) {
   160 |     throw new Error(`Expected outer map 0xa2, got 0x${buf[pos].toString(16)}`)
   161 |   }
   162 |   pos += 1

+ (mutation): {}

StringLiteral at line 160

   159 |   if (buf[pos] !== 0xa2) {
>  160 |     throw new Error(`Expected outer map 0xa2, got 0x${buf[pos].toString(16)}`)
   161 |   }

+ (mutation): ``

ConditionalExpression at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65
   170 |     || buf[pos + 3] !== 0x71
   171 |   ) {

+ (mutation): false

LogicalOperator at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65
   170 |     || buf[pos + 3] !== 0x71
   171 |   ) {

+ (mutation): (buf[pos] !== 0x63 || buf[pos + 1] !== 0x73 || buf[pos + 2] !== 0x65) && buf[pos + 3] !== 0x71

ConditionalExpression at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65
   170 |     || buf[pos + 3] !== 0x71

+ (mutation): false

LogicalOperator at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65
   170 |     || buf[pos + 3] !== 0x71

+ (mutation): (buf[pos] !== 0x63 || buf[pos + 1] !== 0x73) && buf[pos + 2] !== 0x65

ConditionalExpression at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65

+ (mutation): false

LogicalOperator at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65

+ (mutation): buf[pos] !== 0x63 && buf[pos + 1] !== 0x73

ConditionalExpression at line 167

   166 |   if (
>  167 |     buf[pos] !== 0x63
   168 |     || buf[pos + 1] !== 0x73

+ (mutation): false

ConditionalExpression at line 168

   167 |     buf[pos] !== 0x63
>  168 |     || buf[pos + 1] !== 0x73
   169 |     || buf[pos + 2] !== 0x65

+ (mutation): false

ConditionalExpression at line 169

   168 |     || buf[pos + 1] !== 0x73
>  169 |     || buf[pos + 2] !== 0x65
   170 |     || buf[pos + 3] !== 0x71

+ (mutation): false

ConditionalExpression at line 170

   169 |     || buf[pos + 2] !== 0x65
>  170 |     || buf[pos + 3] !== 0x71
   171 |   ) {

+ (mutation): false

ConditionalExpression at line 182

   181 |   const seqMt = seqHdr >> 5
>  182 |   if (seqMt !== 0) {
   183 |     throw new Error(`seq must be unsigned int, got major type ${seqMt}`)

+ (mutation): false

ConditionalExpression at line 188

   187 |   }
>  188 |   else if (seqAi === 24) {
   189 |     need(1)

+ (mutation): true

ConditionalExpression at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74
   215 |     || buf[pos + 4] !== 0x61
   216 |   ) {

+ (mutation): false

LogicalOperator at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74
   215 |     || buf[pos + 4] !== 0x61
   216 |   ) {

+ (mutation): (buf[pos] !== 0x64 || buf[pos + 1] !== 0x64 || buf[pos + 2] !== 0x61 || buf[pos + 3] !== 0x74) && buf[pos + 4] !== 0x61

ConditionalExpression at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74
   215 |     || buf[pos + 4] !== 0x61

+ (mutation): false

LogicalOperator at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74
   215 |     || buf[pos + 4] !== 0x61

+ (mutation): (buf[pos] !== 0x64 || buf[pos + 1] !== 0x64 || buf[pos + 2] !== 0x61) && buf[pos + 3] !== 0x74

ConditionalExpression at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74

+ (mutation): false

LogicalOperator at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74

+ (mutation): (buf[pos] !== 0x64 || buf[pos + 1] !== 0x64) && buf[pos + 2] !== 0x61

ConditionalExpression at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61

+ (mutation): false

LogicalOperator at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61

+ (mutation): buf[pos] !== 0x64 && buf[pos + 1] !== 0x64

ConditionalExpression at line 211

   210 |   if (
>  211 |     buf[pos] !== 0x64
   212 |     || buf[pos + 1] !== 0x64

+ (mutation): false

ConditionalExpression at line 212

   211 |     buf[pos] !== 0x64
>  212 |     || buf[pos + 1] !== 0x64
   213 |     || buf[pos + 2] !== 0x61

+ (mutation): false

ConditionalExpression at line 213

   212 |     || buf[pos + 1] !== 0x64
>  213 |     || buf[pos + 2] !== 0x61
   214 |     || buf[pos + 3] !== 0x74

+ (mutation): false

ConditionalExpression at line 214

   213 |     || buf[pos + 2] !== 0x61
>  214 |     || buf[pos + 3] !== 0x74
   215 |     || buf[pos + 4] !== 0x61

+ (mutation): false

ConditionalExpression at line 215

   214 |     || buf[pos + 3] !== 0x74
>  215 |     || buf[pos + 4] !== 0x61
   216 |   ) {

+ (mutation): false

ConditionalExpression at line 227

   226 |   let length: number
>  227 |   if (ai <= 23) {
   228 |     length = ai

+ (mutation): false

EqualityOperator at line 227

   226 |   let length: number
>  227 |   if (ai <= 23) {
   228 |     length = ai

+ (mutation): ai < 23

…and 2034 more surviving mutants not shown. See the HTML report for the full list.

[ng]

Working the top surviving file, src/streaming/mqttBridge.ts (220 surviving — largest single contributor).

PR #635 adds payload-content mutation coverage (no source changes). Scoped Stryker on this file: 220 → 32 surviving, file score 61.6% → 92.18%.

The remaining 32 are equivalent mutants — slugify's own empty-string fallback (L150), JSON.stringify dropping undefined (L302), JSON.parse whitespace-tolerance (L604/605), safePublish's connected-guard masking early-returns (L446/790/818), setTimeout timing values (L693/821), Math.random() clientId entropy (L676/725), shutdown guard internals (L796), and info-level console.log strings (L711/749/760/797).