Surface LAL drop reason in DSL live-debugging

[wu-sheng]

Surface the drop reason in LAL live-debugging

• If this is non-trivial feature, paste the links/URLs to the design doc.
• Update the documentation to include this new feature.
• Tests(including UT, IT, E2E) are added to verify the new feature.

When a LAL rule stops a log at a parse step — a json {} / yaml {} parse failure, a text { regexp } non-match, or a non-log-body input — DSL live-debugging could only show continueOn=false (that a step stopped, never why); an operator had to read the OAP server log or the source to find out. This adds a human-readable drop reason to the live-debug capture.

How it works

• ExecutionContext.dropReason(String) / dropReason() are set at the LAL drop sites in FilterSpec (json/yaml parse failure → the parse exception; non-log-body input → an input-type mismatch message) and TextParserSpec (regexp non-match).
• The shared debug Sample gains an optional reason field. It is non-final with a setter, so the shared 5-arg constructor and the MAL / OAL recorders are unchanged (reason is LAL-populated today, but the field is available to all three DSL debuggers).
• The LAL recorder stamps Sample.reason from ctx.dropReason() only when the step stopped (continueOn == false), so the reason lands exactly on the parser step that halted the pipeline.
• The reason flows through the dsl-debugging REST session response (sampleToJson / clusterSampleToJson) and the cluster-forward proto (ClusterSample.reason = 6), so it works for both single-node and peer-forwarded sessions.
• Sample's TYPE_* constants now carry inline per-DSL usage comments (INPUT/FUNCTION/OUTPUT = all; FILTER = MAL+OAL; AGGREGATION = OAL only).

Testing — the live LAL execution test gains a dropReason assertion; the extended feature cases prove a json {} parse failure, an abortOnFailure false continuation, and a text { regexp } non-match each record the reason (the captured json reason is e.g. json parse failed: com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'plain'…).

Follow-up (separate horizon-ui PR): the OAP protocol now carries reason, but the UI (packages/api-client SessionSample, LiveDebuggerView.vue) still needs a reason? field + rendering to display it.

• If this pull request closes/resolves/fixes an existing issue, replace the issue number. Closes #.
• Update the CHANGES log.

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[Copilot]

Pull request overview

This PR enhances SkyWalking OAP’s DSL live-debugging for LAL by carrying a human-readable “drop reason” through the execution context, debugger samples, REST response, and cluster-forwarding protocol, so operators can see why a step stopped instead of only continueOn=false.

Changes:

• Add ExecutionContext.dropReason(...) / dropReason() and set it at key LAL drop sites (json/yaml parse failures, regexp non-match, input-type mismatch).
• Extend the shared debug Sample + cluster proto + REST JSON output to include an optional reason.
• Add/extend tests and feature-case expectations to assert drop-reason propagation, and document the feature in changes.md.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
oap-server/server-admin/dsl-debugging/src/main/proto/dsl-debugging-cluster.proto	Adds ClusterSample.reason to forward drop reason across nodes.
oap-server/server-admin/dsl-debugging/src/main/java/.../session/Sample.java	Adds optional reason field and includes it in byte-size accounting.
oap-server/server-admin/dsl-debugging/src/main/java/.../rest/DSLDebuggingRestHandler.java	Emits reason in REST session sample JSON when present.
oap-server/server-admin/dsl-debugging/src/main/java/.../lal/LALDebugRecorderImpl.java	Stamps Sample.reason from ExecutionContext.dropReason() when a step stops.
oap-server/server-admin/dsl-debugging/src/main/java/.../cluster/DSLDebuggingClusterServiceImpl.java	Copies Sample.reason into ClusterSample.reason.
oap-server/analyzer/log-analyzer/src/test/resources/.../execution-basic.data.yaml	Adds expected dropReason assertions for feature cases.
oap-server/analyzer/log-analyzer/src/test/java/.../LALScriptExecutionTest.java	Validates ctx.dropReason() contains expected substrings.
oap-server/analyzer/log-analyzer/src/main/java/.../parser/TextParserSpec.java	Records drop reason on regexp non-match.
oap-server/analyzer/log-analyzer/src/main/java/.../filter/FilterSpec.java	Records drop reasons for json/yaml parse failures and non-log-body inputs.
oap-server/analyzer/log-analyzer/src/main/java/.../dsl/ExecutionContext.java	Introduces KEY_DROP_REASON and accessor/mutator APIs.
docs/en/changes/changes.md	Documents the new live-debug drop-reason capability.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.