feat(voyage): add lib/exporters/textfile-format.mjs — Prometheus text-format pure transform SC #12

Step 9 av v4.1-execute (Wave 2, Session 3).

Pure function transformToPrometheus(records) → Prometheus text-format 0.0.4.

Hard rules:
- NO client-side timestamps (research/01 node_exporter#1284 mitigation)
- Allowlist-redacted records ONLY (caller responsibility — Step 11 enforces)
- UTF-8 metric names normalized: lowercase, [.\\-\\s] → _, voyage_ prefix
- Empty input → empty string output
- Sorted output for determinism (snapshot-test-friendly)

Heuristic metric typing:
- counter: *_total, *_count, *_passed, *_failed, *_skipped
- histogram: *_ms, *_duration, *_p\\d+, *_seconds
- gauge: everything else (Prometheus convention)

Snapshot: tests/fixtures/expected.prom byte-for-byte match.
Regenerate: node scripts/gen-expected-prom.mjs > tests/fixtures/expected.prom

Tester (6 nye, baseline 400 → 406):
- Snapshot byte-for-byte match (SC #12)
- Empty input handling (null, undefined, [])
- Allowlist-redaction sanity (post-bash-stats uten command_excerpt)
- NO client-side timestamps (token-count-assertion per linje)
- normalizeMetricName edge-cases
- Determinism (identisk input → identisk output)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/voyage/tests/fixtures/expected.prom

@@ -0,0 +1,54 @@
+# HELP voyage_trekbrief_interview_turns voyage stats — trekbrief_interview_turns
+# TYPE voyage_trekbrief_interview_turns gauge
+voyage_trekbrief_interview_turns{_schema_id="trekbrief",slug="add-auth",mode="default",profile="economy",profile_source="env"} 7
+# HELP voyage_trekbrief_research_topics voyage stats — trekbrief_research_topics
+# TYPE voyage_trekbrief_research_topics gauge
+voyage_trekbrief_research_topics{_schema_id="trekbrief",slug="add-auth",mode="default",profile="economy",profile_source="env"} 3
+# HELP voyage_trekbrief_review_iterations voyage stats — trekbrief_review_iterations
+# TYPE voyage_trekbrief_review_iterations gauge
+voyage_trekbrief_review_iterations{_schema_id="trekbrief",slug="add-auth",mode="default",profile="economy",profile_source="env"} 2
+# HELP voyage_trekexecute_steps_failed voyage stats — trekexecute_steps_failed
+# TYPE voyage_trekexecute_steps_failed counter
+voyage_trekexecute_steps_failed{_schema_id="trekexecute",plan="trekplan-add-auth.md",plan_type="plan",mode="execute",result="completed",profile="premium",profile_source="inheritance"} 0
+# HELP voyage_trekexecute_steps_passed voyage stats — trekexecute_steps_passed
+# TYPE voyage_trekexecute_steps_passed counter
+voyage_trekexecute_steps_passed{_schema_id="trekexecute",plan="trekplan-add-auth.md",plan_type="plan",mode="execute",result="completed",profile="premium",profile_source="inheritance"} 12
+# HELP voyage_trekexecute_steps_skipped voyage stats — trekexecute_steps_skipped
+# TYPE voyage_trekexecute_steps_skipped counter
+voyage_trekexecute_steps_skipped{_schema_id="trekexecute",plan="trekplan-add-auth.md",plan_type="plan",mode="execute",result="completed",profile="premium",profile_source="inheritance"} 0
+# HELP voyage_trekexecute_steps_total voyage stats — trekexecute_steps_total
+# TYPE voyage_trekexecute_steps_total counter
+voyage_trekexecute_steps_total{_schema_id="trekexecute",plan="trekplan-add-auth.md",plan_type="plan",mode="execute",result="completed",profile="premium",profile_source="inheritance"} 12
+# HELP voyage_trekplan_agents_deployed voyage stats — trekplan_agents_deployed
+# TYPE voyage_trekplan_agents_deployed gauge
+voyage_trekplan_agents_deployed{_schema_id="trekplan",slug="add-auth",mode="default",profile="premium",profile_source="flag"} 7
+# HELP voyage_trekplan_codebase_files voyage stats — trekplan_codebase_files
+# TYPE voyage_trekplan_codebase_files gauge
+voyage_trekplan_codebase_files{_schema_id="trekplan",slug="add-auth",mode="default",profile="premium",profile_source="flag"} 156
+# HELP voyage_trekplan_deep_dives voyage stats — trekplan_deep_dives
+# TYPE voyage_trekplan_deep_dives gauge
+voyage_trekplan_deep_dives{_schema_id="trekplan",slug="add-auth",mode="default",profile="premium",profile_source="flag"} 2
+# HELP voyage_trekplan_research_briefs_used voyage stats — trekplan_research_briefs_used
+# TYPE voyage_trekplan_research_briefs_used gauge
+voyage_trekplan_research_briefs_used{_schema_id="trekplan",slug="add-auth",mode="default",profile="premium",profile_source="flag"} 3
+# HELP voyage_trekresearch_agents_external voyage stats — trekresearch_agents_external
+# TYPE voyage_trekresearch_agents_external gauge
+voyage_trekresearch_agents_external{_schema_id="trekresearch",slug="add-auth",mode="default",scope="both",profile="premium",profile_source="default"} 3
+# HELP voyage_trekresearch_agents_local voyage stats — trekresearch_agents_local
+# TYPE voyage_trekresearch_agents_local gauge
+voyage_trekresearch_agents_local{_schema_id="trekresearch",slug="add-auth",mode="default",scope="both",profile="premium",profile_source="default"} 5
+# HELP voyage_trekresearch_contradictions voyage stats — trekresearch_contradictions
+# TYPE voyage_trekresearch_contradictions gauge
+voyage_trekresearch_contradictions{_schema_id="trekresearch",slug="add-auth",mode="default",scope="both",profile="premium",profile_source="default"} 1
+# HELP voyage_trekresearch_dimensions voyage stats — trekresearch_dimensions
+# TYPE voyage_trekresearch_dimensions gauge
+voyage_trekresearch_dimensions{_schema_id="trekresearch",slug="add-auth",mode="default",scope="both",profile="premium",profile_source="default"} 4
+# HELP voyage_trekresearch_open_questions voyage stats — trekresearch_open_questions
+# TYPE voyage_trekresearch_open_questions gauge
+voyage_trekresearch_open_questions{_schema_id="trekresearch",slug="add-auth",mode="default",scope="both",profile="premium",profile_source="default"} 2
+# HELP voyage_trekreview_duration_ms voyage stats — trekreview_duration_ms
+# TYPE voyage_trekreview_duration_ms histogram
+voyage_trekreview_duration_ms{_schema_id="trekreview",slug="add-auth",verdict="ALLOW",mode="default",profile="balanced",profile_source="flag"} 4521
+# HELP voyage_trekreview_reviewed_files_count voyage stats — trekreview_reviewed_files_count
+# TYPE voyage_trekreview_reviewed_files_count counter
+voyage_trekreview_reviewed_files_count{_schema_id="trekreview",slug="add-auth",verdict="ALLOW",mode="default",profile="balanced",profile_source="flag"} 18

plugins/voyage/tests/fixtures/stats-sample.jsonl

@@ -0,0 +1,5 @@
+{"_schema_id":"trekplan","ts":"2026-05-09T08:00:00.000Z","slug":"add-auth","mode":"default","codebase_files":156,"agents_deployed":7,"deep_dives":2,"research_briefs_used":3,"profile":"premium","profile_source":"flag"}
+{"_schema_id":"trekexecute","ts":"2026-05-09T08:30:00.000Z","plan":"trekplan-add-auth.md","plan_type":"plan","mode":"execute","result":"completed","steps_total":12,"steps_passed":12,"steps_failed":0,"steps_skipped":0,"profile":"premium","profile_source":"inheritance"}
+{"_schema_id":"trekreview","ts":"2026-05-09T09:00:00.000Z","slug":"add-auth","verdict":"ALLOW","reviewed_files_count":18,"mode":"default","duration_ms":4521,"profile":"balanced","profile_source":"flag"}
+{"_schema_id":"trekbrief","ts":"2026-05-09T07:00:00.000Z","slug":"add-auth","mode":"default","interview_turns":7,"review_iterations":2,"research_topics":3,"profile":"economy","profile_source":"env"}
+{"_schema_id":"trekresearch","ts":"2026-05-09T07:30:00.000Z","slug":"add-auth","mode":"default","scope":"both","dimensions":4,"agents_local":5,"agents_external":3,"contradictions":1,"open_questions":2,"profile":"premium","profile_source":"default"}