Tracer.inject now reports whether it wrote context into the carrier, and
index.d.ts was updated to return boolean. index.d.v5.ts still declared
void. inject exists on v5 and this return is not v6-only, so the v5
release type swap (scripts/release/swap-v5-types.js) would ship a stale
void declaration and hide the return value from v5 TypeScript users even
though the runtime provides it. Mirror the signature and JSDoc so the two
public surfaces diverge only by the intended v6 cleanups.

Refs: #9183 (comment)

The prior commit widened Tracer.inject's declared return from void to
boolean across the public surface. That is a breaking TypeScript change:
under strict mode `const x: void = tracer.inject(...)` and returning
`tracer.inject(...)` from a void-typed function stop compiling. It must
not ship on a shipping major.

The runtime already returns the boolean and the internal AWS SDK
producers consume it through the unwrapped DatadogTracer (a plugin's
`this.tracer` resolves to `_tracer._tracer`, and the DSM checkpointer
holds that inner tracer directly), never through the public proxy. So
the boolean stays an internal signal regardless of what the public
`.d.ts` promises.

Freeze the contract per major:

1. index.d.v5.ts and the new index.d.v6.ts declare `inject(): void` —
   the current shipping majors keep their contract.
2. index.d.ts (master is 7.0.0-pre) declares `inject(): boolean` as the
   next-major public API, documented in MIGRATING.md under 6.0 to 7.0.

Generalize the release type swap: swap-v5-types.js only handled v5, so a
v6 release would publish the v7 index.d.ts. Rename it to
swap-legacy-types.js and pick index.d.v<major>.ts by the release major;
the newest major has no frozen file and is a no-op. Adding a future
frozen surface is now a single file drop. The .v<major>.ts files stay
out of the npm `files` array by design — the swap copies the chosen one
over index.d.ts at pack time, so only index.d.ts ships.

Refs: #9183 (comment)

…9183)

* fix(aws-sdk): record kinesis DSM checkpoint only when context ships

When a Kinesis record exceeds the 1 MiB cap, injectToMessage bailed after
setDSMCheckpoint had already run: it recorded a produce checkpoint, advanced the
pathway context, and tagged pathway.hash on the span, yet params.Data was never
written so nothing shipped on the wire. The producer left a dangling pathway edge
no consumer completes and a span tagged with a hash for a message it never sent.

Gate on the trace-context payload before setDSMCheckpoint so a record we cannot
ship records no checkpoint, advances no pathway, and tags no hash. The bounded
dd-pathway-ctx-base64 bytes are added after the gate; they cannot realistically
tip a record that already cleared 1 MiB with room for them.

EventBridge shares this checkpoint-before-gate pattern and is tracked separately
in #8476; this change is Kinesis-only.

* refactor(aws-sdk): track message injection with a boolean, drop isEmpty

The kinesis, sqs, and sns producers decided whether to attach `_datadog`
by re-scanning the freshly built `ddInfo` carrier with an `isEmpty`
for-in helper. A local `injected` flag set at each population site
carries the same fact without the per-send rescan or the shared helper,
and matches `DsmPathwayCodec.encode`'s own `!dataStreamsContext.hash`
guard on the sns path so an empty pathway context no longer counts as
injected.

Replace the faked kinesis inject-to-message spec — an
`Object.create(Kinesis.prototype)` instance with a stubbed tracer — with
a real agent-loaded regression in kinesis.dsm.spec.js: a record that
only clears the 1 MiB cap before the trace context is attached must
record no produce checkpoint, asserted through the `putRecord` span
carrying no `pathway.hash`. Drop the sqs unit case that asserted a
carrier state (`injectTraceContext` true, `inject` a no-op) no real
caller reaches.

* refactor(core): return whether inject wrote anything into the carrier

`Tracer.inject` and every propagator now report whether they wrote any
context, so the AWS SDK messaging producers stop attaching an empty
`_datadog` message attribute when nothing was injected. Previously they
assumed a write happened whenever injection was attempted, which shipped an
empty carrier under `DD_TRACE_PROPAGATION_STYLE_INJECT=none` and whenever a
disabled-APM-tracing (standalone ASM) trace was stripped after injection.

The standalone ASM strip runs on the `dd-trace:span:inject` channel after the
propagator writes, so the text_map propagator re-checks the `_dd.p.ts` trace
tag when APM tracing is disabled to keep the returned value truthful without
rescanning the carrier.

* test: align inject test doubles with the boolean carrier-write return

`Tracer.inject` now reports whether it wrote context into the carrier, and the
AWS SDK producers read that instead of rescanning with `isEmpty`. Four
expectations still modelled the old `undefined` return and failed in CI:

1. sqs-inject-to-message: stubs mutate the carrier but returned `undefined`, so
   the producer dropped `_datadog`; return `true` from the writing stubs and
   `false` from the no-op default.
2. dd-trace-api: `inject` forwards its return through the public API, now
   `false` for the empty test args; assert `false`.
3. pathway: type the no-hash `encode` argument concretely to clear
   jsdoc/reject-any-type.
4. kinesis.dsm: `assert.match(resource, /^putRecord/)` clears
   eslint-prefer-assert-match.

* fix(aws-sdk): reserve the DSM pathway field before the kinesis size gate

The size gate ran on the trace-context payload before DsmPathwayCodec.encode
appended the fixed-size dd-pathway-ctx-base64 field. A record sitting within 55
bytes of the 1 MiB cap cleared the gate, recorded a checkpoint, and then wrote an
over-cap params.Data that Kinesis rejects, failing the user's putRecord. Reserve
the pathway field's bytes in the gate so a record that only fits without it
records no checkpoint and never ships over the cap.

* fix(types): mirror inject boolean return in the v5 type surface

Tracer.inject now reports whether it wrote context into the carrier, and
index.d.ts was updated to return boolean. index.d.v5.ts still declared
void. inject exists on v5 and this return is not v6-only, so the v5
release type swap (scripts/release/swap-v5-types.js) would ship a stale
void declaration and hide the return value from v5 TypeScript users even
though the runtime provides it. Mirror the signature and JSDoc so the two
public surfaces diverge only by the intended v6 cleanups.

Refs: #9183 (comment)

* fix(types): keep public inject void on v5/v6, expose boolean on v7

The prior commit widened Tracer.inject's declared return from void to
boolean across the public surface. That is a breaking TypeScript change:
under strict mode `const x: void = tracer.inject(...)` and returning
`tracer.inject(...)` from a void-typed function stop compiling. It must
not ship on a shipping major.

The runtime already returns the boolean and the internal AWS SDK
producers consume it through the unwrapped DatadogTracer (a plugin's
`this.tracer` resolves to `_tracer._tracer`, and the DSM checkpointer
holds that inner tracer directly), never through the public proxy. So
the boolean stays an internal signal regardless of what the public
`.d.ts` promises.

Freeze the contract per major:

1. index.d.v5.ts and the new index.d.v6.ts declare `inject(): void` —
   the current shipping majors keep their contract.
2. index.d.ts (master is 7.0.0-pre) declares `inject(): boolean` as the
   next-major public API, documented in MIGRATING.md under 6.0 to 7.0.

Generalize the release type swap: swap-v5-types.js only handled v5, so a
v6 release would publish the v7 index.d.ts. Rename it to
swap-legacy-types.js and pick index.d.v<major>.ts by the release major;
the newest major has no frozen file and is a no-op. Adding a future
frozen surface is now a single file drop. The .v<major>.ts files stay
out of the npm `files` array by design — the swap copies the chosen one
over index.d.ts at pack time, so only index.d.ts ships.

Refs: #9183 (comment)

* fix(propagation): return lazily created carriers

Standalone ASM can remove trace headers while leaving baggage in the carrier. A boolean result reported false for that non-empty carrier, causing AWS messaging producers to drop valid context. Return the carrier internally after its first write while keeping the public tracer API void at the proxy boundary.

Kinesis limits cover Data plus PartitionKey. Include both before recording a DSM checkpoint and allow records at the exact default limit.

No-write injection measured 11.96-12.21 ns eager vs 6.92-6.98 ns lazy; one write in eight measured 29.30-29.46 ns vs 26.09-26.66 ns on Node 24.18.0 / V8 13.6.233.17, 5M iterations x 7 trials with best and worst dropped.

…9183)

* fix(aws-sdk): record kinesis DSM checkpoint only when context ships

When a Kinesis record exceeds the 1 MiB cap, injectToMessage bailed after
setDSMCheckpoint had already run: it recorded a produce checkpoint, advanced the
pathway context, and tagged pathway.hash on the span, yet params.Data was never
written so nothing shipped on the wire. The producer left a dangling pathway edge
no consumer completes and a span tagged with a hash for a message it never sent.

Gate on the trace-context payload before setDSMCheckpoint so a record we cannot
ship records no checkpoint, advances no pathway, and tags no hash. The bounded
dd-pathway-ctx-base64 bytes are added after the gate; they cannot realistically
tip a record that already cleared 1 MiB with room for them.

EventBridge shares this checkpoint-before-gate pattern and is tracked separately
in #8476; this change is Kinesis-only.

* refactor(aws-sdk): track message injection with a boolean, drop isEmpty

The kinesis, sqs, and sns producers decided whether to attach `_datadog`
by re-scanning the freshly built `ddInfo` carrier with an `isEmpty`
for-in helper. A local `injected` flag set at each population site
carries the same fact without the per-send rescan or the shared helper,
and matches `DsmPathwayCodec.encode`'s own `!dataStreamsContext.hash`
guard on the sns path so an empty pathway context no longer counts as
injected.

Replace the faked kinesis inject-to-message spec — an
`Object.create(Kinesis.prototype)` instance with a stubbed tracer — with
a real agent-loaded regression in kinesis.dsm.spec.js: a record that
only clears the 1 MiB cap before the trace context is attached must
record no produce checkpoint, asserted through the `putRecord` span
carrying no `pathway.hash`. Drop the sqs unit case that asserted a
carrier state (`injectTraceContext` true, `inject` a no-op) no real
caller reaches.

* refactor(core): return whether inject wrote anything into the carrier

`Tracer.inject` and every propagator now report whether they wrote any
context, so the AWS SDK messaging producers stop attaching an empty
`_datadog` message attribute when nothing was injected. Previously they
assumed a write happened whenever injection was attempted, which shipped an
empty carrier under `DD_TRACE_PROPAGATION_STYLE_INJECT=none` and whenever a
disabled-APM-tracing (standalone ASM) trace was stripped after injection.

The standalone ASM strip runs on the `dd-trace:span:inject` channel after the
propagator writes, so the text_map propagator re-checks the `_dd.p.ts` trace
tag when APM tracing is disabled to keep the returned value truthful without
rescanning the carrier.

* test: align inject test doubles with the boolean carrier-write return

`Tracer.inject` now reports whether it wrote context into the carrier, and the
AWS SDK producers read that instead of rescanning with `isEmpty`. Four
expectations still modelled the old `undefined` return and failed in CI:

1. sqs-inject-to-message: stubs mutate the carrier but returned `undefined`, so
   the producer dropped `_datadog`; return `true` from the writing stubs and
   `false` from the no-op default.
2. dd-trace-api: `inject` forwards its return through the public API, now
   `false` for the empty test args; assert `false`.
3. pathway: type the no-hash `encode` argument concretely to clear
   jsdoc/reject-any-type.
4. kinesis.dsm: `assert.match(resource, /^putRecord/)` clears
   eslint-prefer-assert-match.

* fix(aws-sdk): reserve the DSM pathway field before the kinesis size gate

The size gate ran on the trace-context payload before DsmPathwayCodec.encode
appended the fixed-size dd-pathway-ctx-base64 field. A record sitting within 55
bytes of the 1 MiB cap cleared the gate, recorded a checkpoint, and then wrote an
over-cap params.Data that Kinesis rejects, failing the user's putRecord. Reserve
the pathway field's bytes in the gate so a record that only fits without it
records no checkpoint and never ships over the cap.

* fix(types): mirror inject boolean return in the v5 type surface

Tracer.inject now reports whether it wrote context into the carrier, and
index.d.ts was updated to return boolean. index.d.v5.ts still declared
void. inject exists on v5 and this return is not v6-only, so the v5
release type swap (scripts/release/swap-v5-types.js) would ship a stale
void declaration and hide the return value from v5 TypeScript users even
though the runtime provides it. Mirror the signature and JSDoc so the two
public surfaces diverge only by the intended v6 cleanups.

Refs: #9183 (comment)

* fix(types): keep public inject void on v5/v6, expose boolean on v7

The prior commit widened Tracer.inject's declared return from void to
boolean across the public surface. That is a breaking TypeScript change:
under strict mode `const x: void = tracer.inject(...)` and returning
`tracer.inject(...)` from a void-typed function stop compiling. It must
not ship on a shipping major.

The runtime already returns the boolean and the internal AWS SDK
producers consume it through the unwrapped DatadogTracer (a plugin's
`this.tracer` resolves to `_tracer._tracer`, and the DSM checkpointer
holds that inner tracer directly), never through the public proxy. So
the boolean stays an internal signal regardless of what the public
`.d.ts` promises.

Freeze the contract per major:

1. index.d.v5.ts and the new index.d.v6.ts declare `inject(): void` —
   the current shipping majors keep their contract.
2. index.d.ts (master is 7.0.0-pre) declares `inject(): boolean` as the
   next-major public API, documented in MIGRATING.md under 6.0 to 7.0.

Generalize the release type swap: swap-v5-types.js only handled v5, so a
v6 release would publish the v7 index.d.ts. Rename it to
swap-legacy-types.js and pick index.d.v<major>.ts by the release major;
the newest major has no frozen file and is a no-op. Adding a future
frozen surface is now a single file drop. The .v<major>.ts files stay
out of the npm `files` array by design — the swap copies the chosen one
over index.d.ts at pack time, so only index.d.ts ships.

Refs: #9183 (comment)

* fix(propagation): return lazily created carriers

Standalone ASM can remove trace headers while leaving baggage in the carrier. A boolean result reported false for that non-empty carrier, causing AWS messaging producers to drop valid context. Return the carrier internally after its first write while keeping the public tracer API void at the proxy boundary.

Kinesis limits cover Data plus PartitionKey. Include both before recording a DSM checkpoint and allow records at the exact default limit.

No-write injection measured 11.96-12.21 ns eager vs 6.92-6.98 ns lazy; one write in eight measured 29.30-29.46 ns vs 26.09-26.66 ns on Node 24.18.0 / V8 13.6.233.17, 5M iterations x 7 trials with best and worst dropped.