fix(audit): require integer phase0 summary row limits

Require non-negative integer maxSessions/maxChannels/maxSkipReasons in summary core and both phase0 summary/capture CLIs to prevent silent flooring of fractional values. Architecture/protocol diagrams reviewed; no flow or API shape changes required.

docs/plans/state.json

@@ -493,6 +493,20 @@
       ],
       "test_status": "pnpm test:run src/audit/phase0BaselineArtifactRetention.test.ts + pnpm typecheck passing"
     },
+    "phase0-live-baseline-summary-limit-integer-validation": {
+      "status": "completed",
+      "date": "2026-02-27",
+      "updated": "2026-02-27",
+      "summary": "Hardened phase-0 summary limit handling by requiring non-negative integer values for `maxSessions`, `maxChannels`, and `maxSkipReasons` in both capture/summarize CLIs and summary core logic, eliminating silent flooring of fractional limits.",
+      "files_modified": [
+        "src/audit/phase0BaselineSummary.ts",
+        "src/audit/phase0BaselineSummary.test.ts",
+        "scripts/capture-phase0-live-baseline.ts",
+        "scripts/summarize-phase0-baseline.ts",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/audit/phase0BaselineSummary.test.ts + pnpm typecheck passing"
+    },
     "phase0-instrumentation-ticket-checklist": {
       "status": "completed",
       "date": "2026-02-25",

scripts/capture-phase0-live-baseline.ts

@@ -45,9 +45,9 @@ function usage(): string {
     '  --sample-out <path>                     Output JSONL sample path override',
     '  --summary-json-out <path>               Output summary JSON path override',
     '  --summary-md-out <path>                 Output summary markdown path override',
-    '  --max-sessions <number>                 Limit session rows in output (default: 20)',
+    '  --max-sessions <integer>                Limit session rows in output (default: 20)',
-    '  --max-channels <number>                 Limit channel rows in output (default: 20)',
+    '  --max-channels <integer>                Limit channel rows in output (default: 20)',
-    '  --max-skip-reasons <number>             Limit skip reason rows in output (default: 10)',
+    '  --max-skip-reasons <integer>            Limit skip reason rows in output (default: 10)',
   ].join('\n');
 }
 
@@ -125,6 +125,20 @@ function parseOptionalNumber(raw: string | undefined, flag: string): number | un
   return parsed;
 }
 
+function parseOptionalInteger(raw: string | undefined, flag: string): number | undefined {
+  const parsed = parseOptionalNumber(raw, flag);
+  if (parsed === undefined) {
+    return undefined;
+  }
+  if (!Number.isInteger(parsed)) {
+    throw new Error(`Invalid ${flag} value "${raw}". Expected an integer.`);
+  }
+  if (parsed < 0) {
+    throw new Error(`${flag} must be greater than or equal to 0.`);
+  }
+  return parsed;
+}
+
 function parseBackendTargets(raw: string | undefined): Phase0BackendTarget[] | undefined {
   const values = parseCsv(raw);
   if (!values) {
@@ -237,9 +251,9 @@ async function main(): Promise<void> {
   const summaryOptions: Phase0BaselineSummaryOptions = {
     channels,
     sources,
-    maxSessions: parseOptionalNumber(values['max-sessions'], '--max-sessions') ?? 20,
+    maxSessions: parseOptionalInteger(values['max-sessions'], '--max-sessions') ?? 20,
-    maxChannels: parseOptionalNumber(values['max-channels'], '--max-channels') ?? 20,
+    maxChannels: parseOptionalInteger(values['max-channels'], '--max-channels') ?? 20,
-    maxSkipReasons: parseOptionalNumber(values['max-skip-reasons'], '--max-skip-reasons') ?? 10,
+    maxSkipReasons: parseOptionalInteger(values['max-skip-reasons'], '--max-skip-reasons') ?? 10,
   };
 
   const backendRouteEvents = backendTargets && backendTargets.length > 0

scripts/summarize-phase0-baseline.ts

@@ -23,9 +23,9 @@ function usage(): string {
     '  --channel <name[,name...]>              Restrict to channels',
     '  --sender <id[,id...]>                   Restrict to senders',
     '  --source <gateway|channel[,..]>         Restrict to sources',
-    '  --max-sessions <number>                 Limit session rows in output (default: 20)',
+    '  --max-sessions <integer>                Limit session rows in output (default: 20)',
-    '  --max-channels <number>                 Limit channel rows in output (default: 20)',
+    '  --max-channels <integer>                Limit channel rows in output (default: 20)',
-    '  --max-skip-reasons <number>             Limit skip reason rows in output (default: 10)',
+    '  --max-skip-reasons <integer>            Limit skip reason rows in output (default: 10)',
     '  --format <markdown|json>                Output format (default: markdown)',
     '  --out <path>                            Write output to file instead of stdout',
   ].join('\n');
@@ -70,6 +70,20 @@ function parseOptionalNumber(raw: string | undefined, flag: string): number | un
   return parsed;
 }
 
+function parseOptionalInteger(raw: string | undefined, flag: string): number | undefined {
+  const parsed = parseOptionalNumber(raw, flag);
+  if (parsed === undefined) {
+    return undefined;
+  }
+  if (!Number.isInteger(parsed)) {
+    throw new Error(`Invalid ${flag} value "${raw}". Expected an integer.`);
+  }
+  if (parsed < 0) {
+    throw new Error(`${flag} must be greater than or equal to 0.`);
+  }
+  return parsed;
+}
+
 function parseSources(raw: string | undefined): Array<'gateway' | 'channel'> | undefined {
   const values = parseCsv(raw);
   if (!values) {
@@ -126,9 +140,9 @@ async function main(): Promise<void> {
     channels: parseCsv(values.channel),
     senders: parseCsv(values.sender),
     sources: parseSources(values.source),
-    maxSessions: parseOptionalNumber(values['max-sessions'], '--max-sessions') ?? 20,
+    maxSessions: parseOptionalInteger(values['max-sessions'], '--max-sessions') ?? 20,
-    maxChannels: parseOptionalNumber(values['max-channels'], '--max-channels') ?? 20,
+    maxChannels: parseOptionalInteger(values['max-channels'], '--max-channels') ?? 20,
-    maxSkipReasons: parseOptionalNumber(values['max-skip-reasons'], '--max-skip-reasons') ?? 10,
+    maxSkipReasons: parseOptionalInteger(values['max-skip-reasons'], '--max-skip-reasons') ?? 10,
   };
 
   const startTime = parseTime(values.since, '--since');

src/audit/phase0BaselineSummary.test.ts

@@ -222,6 +222,14 @@ describe('summarizePhase0Baseline', () => {
     expect(() => summarizePhase0Baseline(events, { maxChannels: -1 })).toThrow('maxChannels');
     expect(() => summarizePhase0Baseline(events, { maxSkipReasons: -1 })).toThrow('maxSkipReasons');
   });
+
+  it('rejects non-integer max limits', () => {
+    const events: AuditEvent[] = [];
+
+    expect(() => summarizePhase0Baseline(events, { maxSessions: 1.5 })).toThrow('maxSessions');
+    expect(() => summarizePhase0Baseline(events, { maxChannels: 1.5 })).toThrow('maxChannels');
+    expect(() => summarizePhase0Baseline(events, { maxSkipReasons: 1.5 })).toThrow('maxSkipReasons');
+  });
 });
 
 describe('renderPhase0BaselineMarkdown', () => {

src/audit/phase0BaselineSummary.ts

@@ -126,10 +126,13 @@ function normalizeLimit(value: number | undefined, optionName: string): number |
   if (!Number.isFinite(value)) {
     throw new Error(`${optionName} must be a finite number.`);
   }
+  if (!Number.isInteger(value)) {
+    throw new Error(`${optionName} must be an integer greater than or equal to 0.`);
+  }
   if (value < 0) {
     throw new Error(`${optionName} must be greater than or equal to 0.`);
   }
-  return Math.floor(value);
+  return value;
 }
 
 function percentile(sortedAscending: number[], pct: number): number {
@@ -197,7 +200,7 @@ function sortGroups(groups: Map<string, RunCounter>, limit?: number): RunOutcome
     });
 
   if (typeof limit === 'number' && Number.isFinite(limit)) {
-    return rows.slice(0, Math.floor(limit));
+    return rows.slice(0, limit);
   }
   return rows;
 }
@@ -213,7 +216,7 @@ function sortSkipReasons(reasons: Map<string, number>, limit?: number): Reaction
     }));
 
   if (typeof limit === 'number' && Number.isFinite(limit)) {
-    return rows.slice(0, Math.floor(limit));
+    return rows.slice(0, limit);
   }
   return rows;
 }