span.setTag(0L, "") or a null value reached TagMap.getAndRemove(long),
which rejects unknown ids, so clearing threw IllegalArgumentException
while every id-keyed setter ignores an unknown id. removeTag(long) now
ignores it too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The long-valued setters prechecked with needsIntercept, but when the
interceptor declined the tag they discarded the box it was given and stored
the primitive. Follow the same precheckIntercept -> setBox shape as the
other primitive setters, so TagMap keeps the box.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

peer.port is declared per direction in the registry (#12713), so it has no
direction-free id: BaseDecorator, shared by client and server decorators,
sets it by name, and the set-by-id tests use an unshared int tag.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Set-path routing is a per-language concern, so it lives in a Java overlay
next to tag-conventions.yaml rather than in the language-agnostic
conventions. The overlay declares the keys that exist only to be routed
(resource.name, error, sampling directives, ...) and lists every tag
TagInterceptor may route. Each listed tag's id carries the INTERCEPTED bit
(bit 1), so a setter called with a constant id can fold the interception
test away. Serial numbers become public so TagInterceptor can switch on
them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

TagInterceptor switches on the tag's serial rather than its name, so a
known tag is matched under any of its names and the *_OTEL_NAME cases go
away. needsIntercept(long) tests the INTERCEPTED bit first, which folds
away for a constant id. split-by-tags entries resolve to serials at
construction (each direction for a name declared per direction); only
custom tags are still matched by name. A test checks that exactly the
tags carrying the bit have a case.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

A name setter resolves a known tag's name to its id once and sets it as the
id-keyed setters do; only a custom tag is still handled by name. The
id-keyed setters no longer look up the name to feed the interceptor, so with
a constant id the interception test folds to the INTERCEPTED bit. Entry
paths (builder ledger, prototypes, default tags) route by the entry's id
and precheck before boxing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The generated nameOf switched over every tag's serial: 491 bytes of
bytecode, too big for C2 to inline, so each id-keyed set paid two
out-of-line calls into it (the span's unknown-id guard and the entry's
name). Read a NAMES_BY_SERIAL array instead; nameOf is now 23 bytes and
inlines at every caller.

Also adds SetTagBenchmark (span setTag by constant id, non-constant id,
name, and custom name, against a bare and a synchronized TagMap store).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The table is always allocated and never resized, so the split check -- the
only run-time check left on a non-intercepted constant-id set -- is a single
load, with no null or length test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The span's unknown-id guard called nameOf; KnownTagCodec.isKnown answers the
same question from the serial and a generated SERIAL_LIMIT, so it folds
away for a constant id. Also note that serials are not stable across
releases.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

DDSpanContext.setTag calls interceptTag only for intercepted tags. Kept out
of line (over FreqInlineSize, 325 bytes of bytecode), it never brings the
profiled handler bodies into setTag's compiled code, which would push setTag
past InlineSmallCode and stop callers inlining it -- the inlining a constant
id needs to fold its interception test. A test now fails if the switch
shrinks below the limit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

An overlay tag exists only to be routed, so the generator now marks it
intercepted without a second listing; intercepted: lists only the tags
declared in tag-conventions.yaml that the tracer also routes. Also restore
the doc comment and @Suppress that the overlay helper displaced, read the
serial limit one way, inline isUnknownTag, and drop an unused default.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

A tag declared once per direction (peer.port) has two ids but one
shared Datadog name, and keyOf resolves that name to neither. An entry
keyed by one of those ids hashed by the id while name-based access
hashed the name as a custom tag, so get/remove/containsKey by name
missed it and a later set by name produced a duplicate key.

Encode a SHARED_NAME flag in the reserved id bit 0 so the check folds
for a constant id. TagMap's id-keyed create/get/remove reject such ids,
and DDSpanContext's id-keyed setters ignore them, as they do unknown
ids, until name resolution knows the span's direction.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Entry's package-private name factories are now custom-only: they skip the
registry and assert the name is not a known tag. Callers that start from a
name resolve it once -- TagMap.set(String, ...) forwards a known tag to
set(long, ...), while getAndSet, put, Ledger.set, putAll and the public
Entry.create(String, ...) API go through anyEntryFor and friends -- so a
custom tag pays one registry lookup instead of two.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

# Conflicts:
#	.github/CODEOWNERS

TagMap.internals() returns a small Internals view whose setKnown(...) skips
the id validation the checked set(long, ...) repeats; DDSpanContext's
id-keyed setters, which have already checked isKeyableById, now use it.
Internals is created per call, so escape analysis removes it.

internals() is marked with a new @restricted(allowedIn = ...) annotation,
and gradle/forbiddenApiFilters/instrumentation.txt bans it in
instrumentation modules, so calling it there fails forbiddenApisMain.
Internals is also where the batched setTagsFrom/TagSink writes will go.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

It exists to be created, used within the expression, and scalar-replaced;
storing one would force a real allocation.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Restricted lives in the new datadog.apicontract package, which had no owner.
Give it the same owner as its sibling datadog.perfcontract.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

peer.port was modeled as one tag per direction: PEER_PORT_INBOUND_ID and
PEER_PORT_OUTBOUND_ID, sharing the Datadog name and marked with a
SHARED_NAME id bit. Two ids under one name kept producing lookup and
supersede bugs: keyOf("peer.port") resolved to neither id, so a value set
by name and one set by id landed in different entries, and tombstones and
getAndSet by name could not find what an id had stored.

The generator now merges a name's per-direction declarations into one tag
with one id (PEER_PORT_ID), and only its OpenTelemetry name depends on the
span's direction: openTelemetryNameOf(id, direction) returns client.port
inbound and server.port outbound. The SHARED_NAME bit, hasSharedName and
isKeyableById go away (bit 0 is left unused), and keyOf("peer.port")
returns PEER_PORT_ID.

KnownTagCodec gains the DIRECTION_* constants and
openTelemetryTagOf(id, direction). Direction-scoped OpenTelemetry names
are still not resolved when written by name.

This is the direction-neutral-id part of #12731's redesign; its
direction-scoped aliases and read-time resolution are left to that PR.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

With peer.port now one direction-neutral tag, its OpenTelemetry name
depends on the span: server.port on a client span, client.port on a
server span. The OTLP JSON and protobuf writers compute the span's
direction once from its span.kind and name each tag for it, so
direction-scoped renames apply too: peer.hostname exports as
server.address on a client span, and network.client.ip as
network.peer.address on a server span.

KnownTagCodec gains directionOf(TagMap) / directionOfKind(String), and
TagMap.EntryReader gains openTelemetryTag(direction), standing in for
the SpanTags helpers #12731 introduces.

Ported from #12731's redesign.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Entry's full constructor and the Internals and Ledger constructors were
private, so javac (targeting Java 8, without nestmates) gave each one a
synthetic access constructor taking the never-loaded class TagMap$1. C2
refuses to inline a call whose signature names an unloaded class
("unloaded signature classes"). So the Internals view the core creates
for each id write could not be scalar-replaced, and every Entry built
through that constructor went through a real call. Making the
constructors package-private removes the accessors and TagMap$1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Several private members were used across TagMap's nested classes, so
javac (targeting Java 8) generated access$ methods for them: Entry's
*2Prim helpers and requireKnownName, TagMap.parentEntryVisible,
TagMap.putEntry and the TagMap.buckets field. Each accessor adds a level
of inlining depth. putEntry's accessor sits on Internals.setKnown, the
core's trusted id-write path. All of these are now package-private.

TagMapSyntheticAccessorTest fails if TagMap or any of its nested classes
gains a synthetic accessor again. It is the prototype for the
@NoSyntheticAccess contract (APMLP-1976).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Master now has #12715 (set-by-id, squashed) and #12037 (decorator
SpanPrototype). Conflicts resolve to this branch's newer id-keyed code,
plus:
- getAndSet finds its inherited prior by the entry's id (#12715's last fix);
  the shared-name test for it is dropped, since peer.port now has one id.
- #12037's resolveSplitByTagsPrecedence checks component by id and language
  by name against the serial-indexed split-by-tags table.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Brings the three classes back over jacoco's thresholds: the trusted
setters' Object/float/double overloads, isIntercepted, isKnown's range
edges, canonicalTagName, span-kind direction, and an entry's directional
OpenTelemetry name.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

build-logic is a separate Gradle build, so the root spotlessApply never
formats it. Three generator lines were wrapped where its Kotlin formatter
keeps them on one line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Set sites checked per tag:

- trace_level: process_id (a local root tag) and ai_guard.event (set on
  the local root of a trace holding an AI Guard evaluation span).
- base: events, the span events as JSON when the writer can't encode
  them natively, alongside _dd.span_links.
- exception_replay, a product mixin on every span:
  error.debug_info_captured.
- rpc: status.code and status.description (gRPC, set by literal).
- db.client: couchbase.operation_id (set by literal).
- Java servlet.request: user.principal (servlet containers) and timeout
  (Servlet 3 async timeouts); spring.webflux.client: event.

Never registered, each with its reason: thread.id and thread.name are
span fields the serializers write, never stored as tags;
runtime_version is a profiling and telemetry tag; t0 is a baggage key;
dd.env, dd.service and dd.version are log correlation (MDC) keys.

The CI Visibility constants among them (os.*, runtime.*,
_dd.host.vcpu_count, itr_correlation_id, pr.number, and library_version,
a span tag only on CI test traces) join the CI Visibility families.
That leaves no single unregistered constant: what remains is CI
Visibility, for a follow-up PR.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

db.client carried system-specific tags in every DB span's clique.
System-specific tags extend one concept, so they become types:

- db.client keeps what any database client sets: type, instance,
  operation, user, statement, and a command's outcome
  (db.command.cancelled and .results.count, set by Redis and Memcached).
- db.sql (JDBC, R2DBC): db.pool.name, db.schema, db.warehouse.
- db.cassandra, db.couchbase (seed nodes, bucket, operation id),
  db.redis (db.redis.dbIndex), and db.mongo.
- Database Monitoring is a product add-on, so its propagation tags
  become a dbm mixin on db.sql and db.mongo, where it injects comments.

With #12882's coloring the 213 tags use 47 slots, down from 57
(elasticsearch.transport).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Span types are what instrumentation developers work with most, so they
lead the file, ahead of the routing-only keys and the intercepted list.
The header now describes both halves of the file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>