Generate KnownTags from tag-conventions via the tag-registry code generator (phase 2)

[dougqh]

What Does This Do

Replaces the hand-maintained known-tag table with one generated from a single source of truth (tag-conventions.yaml + a Java overlay), so tag ids / the id↔name resolver / (later) per-type layouts stop drifting across core, instrumentation, and language tracers.

Generator (buildSrc)

Modeled on SupportedConfigPlugin (data file → .java via PrintWriter):

• TagRegistryGeneratorPlugin + GenerateKnownTagsTask — read tag-conventions.yaml (domain) + tag-conventions.java.yaml (Java overlay: intercepted hints + virtual/special registry), resolve per-type tag sets (extends/include/applies, de-duped), assign ids in stable serial order, and greedily graph-color the colorable set into slots.
• KnownTagsEmitter — emits google-java-format-clean Java to committed internal-api/src/generated with a literal id + // tagId(serial=…, group=…, field=…) audit comment (literal ⟹ javac constant-folds; comment ⟹ auditable).
• verifyKnownTags — regenerates + git-diffs to catch stale commits. Generated classes are jacoco-excluded.

Committing the generated sources also lets us audit what ids/layout any release branch shipped via git checkout.

internal-api

• Deletes the interim hand-maintained src/main/.../KnownTags.java in favor of the generated src/generated/.../KnownTags.java (byte-equal ids — the equivalence gate).
• Read-through stays chain-aware: keeps this stack's multi-level parentDenseVisible over the pre-reconcile single-level form.
• Generated keyOf table uses StringIndex.EmbeddingSupport (matching the tagset base rename) in both the emitter and its committed output, so regeneration is drift-free.

Verification

:internal-api:generateKnownTags (no drift), verifyKnownTags, KnownTagsTest, TagMapDenseForkedTest, TagMapDenseFuzzForkedTest, spotlessJavaCheck, spotbugsMain — all green.

Stack

tagset → dense-store (#12045) → two-tier bloom (#12046) → **generator**. Base dougqh/bloom-v2. Supersedes old #11961.

Non-goals (follow-on)

Wiring SpanLayouts into the dense store; full virtual-dispatch table → TagInterceptor retirement; bandwidth-minimizing packer (greedy is v1).

🤖 Generated with Claude Code

[datadog-prod-us1-4]

Bits has a CI fix ready

🟢 Investigated · 🟢 Fix prepared · ⚪ Validation skipped · 🟠 Ready

CoreTracer.java had a line exceeding the required formatter’s wrapping rules. Wrapped the dense-tag initialization comment to comply with the repository style.

Commit fix to this PR

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View in Datadog | Reviewed commit e6800b8 · Any feedback? Reach out in #deveng-pr-agent

[datadog-prod-us1-4]

🎯 Code Coverage (details)
• Patch Coverage: 43.53%
• Overall Coverage: 57.38% (-0.02%)

_{This comment will be updated automatically if new data arrives.
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[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	14.82 s	14.74 s	[-0.4%; +1.4%] (no difference)
startup:insecure-bank:tracing:Agent	13.60 s	13.76 s	[-2.1%; -0.2%] (maybe better)
startup:petclinic:appsec:Agent	17.04 s	17.00 s	[-0.7%; +1.2%] (no difference)
startup:petclinic:iast:Agent	17.08 s	17.07 s	[-0.8%; +1.0%] (no difference)
startup:petclinic:profiling:Agent	16.76 s	16.88 s	[-1.8%; +0.4%] (no difference)
startup:petclinic:sca:Agent	16.98 s	16.89 s	[-0.3%; +1.4%] (no difference)
startup:petclinic:tracing:Agent	16.20 s	16.20 s	[-1.0%; +1.0%] (no difference)

Commit: e6800b8c · CI Pipeline · Benchmarking Platform UI

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Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.