[subganapathy]

Trim the name and refuse an empty one with InvalidArgument instead of returning hello .

Review fixture P4 from the evaluation plan: a business-logic change that can error on existing input.

[subganapathy]

impact: 🟡 WARNING

No blocking issue: hello has no real production caller today (service.yaml says so; frontend's Home handler is Unimplemented and never builds a HelloRequest), so the behavior change from 'hello '→InvalidArgument for blank names breaks nobody deployed. Two warnings stand: the canary's AnalysisTemplate excludes InvalidArgument from its error-ratio query, so a bad regression here would promote undetected; and there's no alert on the new error code plus thin test coverage (literal "" untested, e2e blind to the status code).

Worst case: Every hello.v1.HelloService/Hello call whose name is empty or whitespace, which previously succeeded with "hello ", now fails with gRPC InvalidArgument (code 3). Blast radius as measured: one cluster, e1-dev, one ready pod (instances query: {cluster=e1-dev} 1), service type ClusterIP only (exposure query: hello, hello-canary both ClusterIP — nothing reachable from outside the cluster), and exactly one caller, workload traffic in namespace frontend under principal spiffe://cluster.local/ns/frontend/sa/frontend at 1.5 rps (callers query). No prod or staging instance appears in any measured series, and discover.yaml answers record staging_exists=no. So the realistic worst case is: the single internal traffic generator (and, later, the real frontend service listed in service.yaml authorizedCallers) starts receiving code 3 on blank-name requests; because the canary AnalysisTemplate server-errors (deploy/base/rollout.yaml) counts only code="Unknown|Internal|DataLoss|DeadlineExceeded", a 100%-InvalidArgument regression would not fail the canary gate and, with no alerting rules in the metrics stack (discover.yaml stack.metrics), nothing would page. Secondary worst case: if CI's e2e probe or the toxic-client conformance suite asserts the old empty-name response, the change never ships (red CI) rather than breaking production. (reduced proof)

What this service runs on (discovered)

• mesh: Istio 1.31.1 sidecar mesh, strict mTLS — discover.yaml verified; VirtualService/NetworkPolicy manifests present
• deploy: Argo CD + Argo Rollouts canary with AnalysisTemplate server-errors — kube_replicaset_owner → owner_kind=Rollout (measured); deploy/base/rollout.yaml
• admission: PSS enforce=restricted, no policy engine — discover.yaml stack.admission; deploy/base/rollout.yaml securityContext
• autoscaler: KEDA ScaledObject on vikrant_inflight_rpcs, min 3/max 10 (base), e1-dev measured ceiling=2/floor=1 — deploy/base/autoscaling.yaml; measured ceiling/floor queries
• metrics: prometheus-compatible, vikrant_* families, no alerting rules configured — discover.yaml stack.metrics; measured alerts query empty

Property	Verdict
correct	info	Trim+reject is not constrained by any documented contract (proto has no validation note, README silent), status/codes packages are already satisfied by go.mod's existing grpc v1.84.0 dependency, and the change touches only service-team-owned files so check-stamp/check-generated are unaffected.
reversible	info	No stored state, proto, or config format changes; service.yaml itself states hello has no real callers yet, and frontend's own code (confirmed) never constructs a HelloRequest — the only observed caller is a synthetic dev traffic generator, so no deployed caller depends on the old 'hello ' response for blank input.
within budget	info	Adds no outbound call or fan-out; trimming and early-return reduce work on the rejected path; current headroom (ceiling=2, desired=1, inflight=0, p99=65.9ms) is irrelevant since load is unaffected.
stable under failure	info	InvalidArgument is absent from both VirtualService retryOn sets (idempotent and primary routes) and the client has no service-config retryPolicy (client/client_test.go asserts none), so the new error cannot be amplified into a retry storm.
progressively delivered	warning	The canary AnalysisTemplate server-errors (deploy/base/rollout.yaml, second document) filters code=~"Unknown
available	info	No manifest, probe, resource, or security-context change in this diff; PDB, spread and admission settings are untouched.
secure	info	The rejection path logs/returns only the constant string "name is required", never req.GetName(), so no caller-supplied value is exposed; no permission or authz change.
observable	warning	vikrant_rpcs_handled_total already labels by code so InvalidArgument becomes visible to the measured errors query, but no alerting rule exists in this metrics backend (measured alerts query empty) and there is no flag to revert the validation without a redeploy.
proven	warning	The unit tests cover trimming and a whitespace-only rejection, but the literal empty string "" is no longer exercised on either path, no end-to-end test asserts the business behaviour of a blank name (the probe's 'reach'/'no-errors' matchers are blind to InvalidArgument), and client/client_test.go and frontend never exercise HelloRequest at all.

[info] reversible — hello has no production caller to break: service.yaml's own header states "Nobody may call it yet", and smallStepGiantLeap/frontend's only handler (Home) is Unimplemented with zero references to hellov1/HelloRequest anywhere in its repo. (confidence 0.85)

• evidence (config): hello repo · service.yaml line 1 → "service.yaml for hello, owned by the hello team. Nobody may call it yet."
• evidence (doc): org-finder on smallStepGiantLeap/frontend · grep -rn HelloRequest|hellov1|NewHelloServiceClient → zero hits; Home RPC returns codes.Unimplemented
• evidence (metric): measured callers query (discover.yaml) → only source_workload=traffic under frontend's service account, documented in discover.yaml answers as a synthetic load generator
• recommend: None required; if a future frontend revision implements Home and calls Hello, re-check whether it can send blank names.

[warning] progressively delivered — The canary's only automated judgment, the server-error-ratio AnalysisTemplate, excludes code 3 (InvalidArgument), so this behavior change is not gated by the staged rollout the platform provides. (confidence 0.90)

• evidence (config): deploy/base/rollout.yaml · AnalysisTemplate server-errors, prometheus.query → code=~"Unknown|Internal|DataLoss|DeadlineExceeded" — InvalidArgument absent
• recommend: Accept as a known gap for business-logic error codes, or extend the AnalysisTemplate (platform-owned, regenerated from service.yaml) to also watch a business-error ratio before relying on canary to catch future contract changes like this one.

[warning] observable — No alert watches vikrant_rpcs_handled_total{code="InvalidArgument"}, so a caller-visible spike in rejections (e.g. a buggy upstream sending blank names) would page nobody. (confidence 0.80)

• evidence (metric): measured alerts query · ALERTS{alertstate="firing",namespace="hello"} → no data (empty)
• evidence (config): .paved-agent/discover.yaml · stack.metrics.is → "...no alerting rules"
• recommend: If/when hello gets a real caller, add an alert on the InvalidArgument rate for Hello, or at minimum document this failure mode in the service's runbook.

[warning] proven — The new table-test drops the literal empty string "" entirely (it tests " " for rejection and " Ada " for trimming), and no end-to-end test observes the business behaviour: the e2e probe's reach/no-errors matchers treat InvalidArgument the same as OK. (confidence 0.75)

• evidence (diff): internal/handlers/hello_service_test.go → map keys "Subramanian"/" Ada " and a single " " case in TestHelloRejectsEmptyName; literal "" untested
• evidence (config): e2e/run.sh · matches() reach/no-errors cases → reach: any CODE not PermissionDenied|Unavailable|DeadlineExceeded passes; no-errors: failure list is Unavailable,DeadlineExceeded,Interna...
• recommend: Add a literal "" case to the table test for completeness; note for future contract changes that e2e cannot catch business-logic status-code regressions as currently written.

❓ Question q1

Does the dev traffic generator (workload 'traffic', running under spiffe://cluster.local/ns/frontend/sa/frontend) ever send an empty or whitespace-only name to Hello?

Blocks: reversible. Reply yes or no on this thread; I will write the file and the review restarts on the push.

if yes → .paved-agent/discover.yaml

answers:
  - {question: traffic_generator_sends_blank_names, answer: "yes", detail: "the dev traffic generator (workload traffic, ns frontend) sends blank/whitespace names and will now see InvalidArgument instead of 200 for those calls"}

if no → .paved-agent/discover.yaml

answers:
  - {question: traffic_generator_sends_blank_names, answer: "no", detail: "the dev traffic generator always sends a non-empty name; this change cannot affect its traffic"}

• unknown: Whether the synthetic traffic generator (workload 'traffic', frontend namespace/SA) ever sends a blank or whitespace-only name, which would turn its requests from 200 to InvalidArgument in dev metrics. (blocks reversible); tried: org-finder searched smallStepGiantLeap/frontend (the declared identity) and found no HelloRequest construction there at all, i.e. the generator is not frontend's own code

_{instantiate sesn_011LC3XR62mnixp6TgDMz9fR: 10 input (79368 cached), 6247 output tokens, 86s active · execute sesn_01Ug9fQwRzgVcDAcfKqTEd6w: 50 input (710498 cached), 17090 output tokens, 194s active}

[subganapathy]

impact: 🟡 WARNING

No blocking issue: hello has no real production caller today (service.yaml says so; frontend's Home handler is Unimplemented and never builds a HelloRequest), so the behavior change from 'hello '→InvalidArgument for blank names breaks nobody deployed. Two warnings stand: the canary's AnalysisTemplate excludes InvalidArgument from its error-ratio query, so a bad regression here would promote undetected; and there's no alert on the new error code plus thin test coverage (literal "" untested, e2e blind to the status code).

Worst case: Every hello.v1.HelloService/Hello call whose name is empty or whitespace, which previously succeeded with "hello ", now fails with gRPC InvalidArgument (code 3). Blast radius as measured: one cluster, e1-dev, one ready pod (instances query: {cluster=e1-dev} 1), service type ClusterIP only (exposure query: hello, hello-canary both ClusterIP — nothing reachable from outside the cluster), and exactly one caller, workload traffic in namespace frontend under principal spiffe://cluster.local/ns/frontend/sa/frontend at 1.5 rps (callers query). No prod or staging instance appears in any measured series, and discover.yaml answers record staging_exists=no. So the realistic worst case is: the single internal traffic generator (and, later, the real frontend service listed in service.yaml authorizedCallers) starts receiving code 3 on blank-name requests; because the canary AnalysisTemplate server-errors (deploy/base/rollout.yaml) counts only code="Unknown|Internal|DataLoss|DeadlineExceeded", a 100%-InvalidArgument regression would not fail the canary gate and, with no alerting rules in the metrics stack (discover.yaml stack.metrics), nothing would page. Secondary worst case: if CI's e2e probe or the toxic-client conformance suite asserts the old empty-name response, the change never ships (red CI) rather than breaking production. (reduced proof)

What this service runs on (discovered)

• mesh: Istio 1.31.1 sidecar mesh, strict mTLS — discover.yaml verified; VirtualService/NetworkPolicy manifests present
• deploy: Argo CD + Argo Rollouts canary with AnalysisTemplate server-errors — kube_replicaset_owner → owner_kind=Rollout (measured); deploy/base/rollout.yaml
• admission: PSS enforce=restricted, no policy engine — discover.yaml stack.admission; deploy/base/rollout.yaml securityContext
• autoscaler: KEDA ScaledObject on vikrant_inflight_rpcs, min 3/max 10 (base), e1-dev measured ceiling=2/floor=1 — deploy/base/autoscaling.yaml; measured ceiling/floor queries
• metrics: prometheus-compatible, vikrant_* families, no alerting rules configured — discover.yaml stack.metrics; measured alerts query empty

Property Verdict
correct info Trim+reject is not constrained by any documented contract (proto has no validation note, README silent), status/codes packages are already satisfied by go.mod's existing grpc v1.84.0 dependency, and the change touches only service-team-owned files so check-stamp/check-generated are unaffected.
reversible info No stored state, proto, or config format changes; service.yaml itself states hello has no real callers yet, and frontend's own code (confirmed) never constructs a HelloRequest — the only observed caller is a synthetic dev traffic generator, so no deployed caller depends on the old 'hello ' response for blank input.
within budget info Adds no outbound call or fan-out; trimming and early-return reduce work on the rejected path; current headroom (ceiling=2, desired=1, inflight=0, p99=65.9ms) is irrelevant since load is unaffected.
stable under failure info InvalidArgument is absent from both VirtualService retryOn sets (idempotent and primary routes) and the client has no service-config retryPolicy (client/client_test.go asserts none), so the new error cannot be amplified into a retry storm.
progressively delivered warning The canary AnalysisTemplate server-errors (deploy/base/rollout.yaml, second document) filters code=~"Unknown
available info No manifest, probe, resource, or security-context change in this diff; PDB, spread and admission settings are untouched.
secure info The rejection path logs/returns only the constant string "name is required", never req.GetName(), so no caller-supplied value is exposed; no permission or authz change.
observable warning vikrant_rpcs_handled_total already labels by code so InvalidArgument becomes visible to the measured errors query, but no alerting rule exists in this metrics backend (measured alerts query empty) and there is no flag to revert the validation without a redeploy.
proven warning The unit tests cover trimming and a whitespace-only rejection, but the literal empty string "" is no longer exercised on either path, no end-to-end test asserts the business behaviour of a blank name (the probe's 'reach'/'no-errors' matchers are blind to InvalidArgument), and client/client_test.go and frontend never exercise HelloRequest at all.
[info] reversible — hello has no production caller to break: service.yaml's own header states "Nobody may call it yet", and smallStepGiantLeap/frontend's only handler (Home) is Unimplemented with zero references to hellov1/HelloRequest anywhere in its repo. (confidence 0.85)

• evidence (config): hello repo · service.yaml line 1 → "service.yaml for hello, owned by the hello team. Nobody may call it yet."
• evidence (doc): org-finder on smallStepGiantLeap/frontend · grep -rn HelloRequest|hellov1|NewHelloServiceClient → zero hits; Home RPC returns codes.Unimplemented
• evidence (metric): measured callers query (discover.yaml) → only source_workload=traffic under frontend's service account, documented in discover.yaml answers as a synthetic load generator
• recommend: None required; if a future frontend revision implements Home and calls Hello, re-check whether it can send blank names.

[warning] progressively delivered — The canary's only automated judgment, the server-error-ratio AnalysisTemplate, excludes code 3 (InvalidArgument), so this behavior change is not gated by the staged rollout the platform provides. (confidence 0.90)

• evidence (config): deploy/base/rollout.yaml · AnalysisTemplate server-errors, prometheus.query → code=~"Unknown|Internal|DataLoss|DeadlineExceeded" — InvalidArgument absent
• recommend: Accept as a known gap for business-logic error codes, or extend the AnalysisTemplate (platform-owned, regenerated from service.yaml) to also watch a business-error ratio before relying on canary to catch future contract changes like this one.

[warning] observable — No alert watches vikrant_rpcs_handled_total{code="InvalidArgument"}, so a caller-visible spike in rejections (e.g. a buggy upstream sending blank names) would page nobody. (confidence 0.80)

• evidence (metric): measured alerts query · ALERTS{alertstate="firing",namespace="hello"} → no data (empty)
• evidence (config): .paved-agent/discover.yaml · stack.metrics.is → "...no alerting rules"
• recommend: If/when hello gets a real caller, add an alert on the InvalidArgument rate for Hello, or at minimum document this failure mode in the service's runbook.

[warning] proven — The new table-test drops the literal empty string "" entirely (it tests " " for rejection and " Ada " for trimming), and no end-to-end test observes the business behaviour: the e2e probe's reach/no-errors matchers treat InvalidArgument the same as OK. (confidence 0.75)

• evidence (diff): internal/handlers/hello_service_test.go → map keys "Subramanian"/" Ada " and a single " " case in TestHelloRejectsEmptyName; literal "" untested
• evidence (config): e2e/run.sh · matches() reach/no-errors cases → reach: any CODE not PermissionDenied|Unavailable|DeadlineExceeded passes; no-errors: failure list is Unavailable,DeadlineExceeded,Interna...
• recommend: Add a literal "" case to the table test for completeness; note for future contract changes that e2e cannot catch business-logic status-code regressions as currently written.

❓ Question q1

Does the dev traffic generator (workload 'traffic', running under spiffe://cluster.local/ns/frontend/sa/frontend) ever send an empty or whitespace-only name to Hello?

Blocks: reversible. Reply yes or no on this thread; I will write the file and the review restarts on the push.

if yes → .paved-agent/discover.yaml

answers:
  - {question: traffic_generator_sends_blank_names, answer: "yes", detail: "the dev traffic generator (workload traffic, ns frontend) sends blank/whitespace names and will now see InvalidArgument instead of 200 for those calls"}

if no → .paved-agent/discover.yaml

answers:
  - {question: traffic_generator_sends_blank_names, answer: "no", detail: "the dev traffic generator always sends a non-empty name; this change cannot affect its traffic"}

• unknown: Whether the synthetic traffic generator (workload 'traffic', frontend namespace/SA) ever sends a blank or whitespace-only name, which would turn its requests from 200 to InvalidArgument in dev metrics. (blocks reversible); tried: org-finder searched smallStepGiantLeap/frontend (the declared identity) and found no HelloRequest construction there at all, i.e. the generator is not frontend's own code

instantiate sesn_011LC3XR62mnixp6TgDMz9fR: 10 input (79368 cached), 6247 output tokens, 86s active · execute sesn_01Ug9fQwRzgVcDAcfKqTEd6w: 50 input (710498 cached), 17090 output tokens, 194s active

No

[subganapathy]

impact: recorded @subganapathy's answer to q1 in .paved-agent/discover.yaml (map[branch:fixture/p4-logic commit:adf776c796372afeb24eac8168be37485f9e7c91 path:.paved-agent/discover.yaml url:https://github.com/smallStepGiantLeap/hello/commit/adf776c796372afeb24eac8168be37485f9e7c91]). The review restarts on the push.

[subganapathy]

impact: 🔴 BLOCKING

Verdict: blocking, on correctness. The change is well-tested and load/security/availability-neutral, but the one caller it could break — the dev traffic generator — has no discoverable source in the org, so the self-added discover.yaml claim that it 'never sends blank names' is an unverified assumption authored by this same PR. Separately (warning): the canary analysis ignores InvalidArgument so a total-rejection regression would auto-promote, and the e2e suite's own simulated caller sends an empty name yet both its reach and no-errors checks would still pass green, meaning no automated gate in this pipeline would catch this change being wrong about its one real caller.

Worst case: hello.v1.HelloService/Hello is the service's only method. After this change every request whose name is empty or all-whitespace gets InvalidArgument (gRPC code 3) instead of hello . If any deployed caller sends such a name — today the only caller measured is source_workload=traffic in namespace frontend, spiffe://cluster.local/ns/frontend/sa/frontend, 1.77-3.1 rps in cluster e1-dev — then 100% of that caller's calls to the service's only method fail, i.e. a total functional outage of hello as seen by that caller. Containment: the fleet has exactly one cluster (fleet: e1-dev, env=dev); hello is ClusterIP only (exposure query: services hello and hello-canary, both ClusterIP), 1 ready instance, no prod cluster exists, no firing alerts, no human end users behind the measured caller. Blast radius is therefore one internal dev service path, but it is that service's entire function, and the promote workflow carries the same digest onward to any environment added later. Two amplifiers to check: the Argo Rollouts analysis gate only counts Unknown|Internal|DataLoss|DeadlineExceeded, so an InvalidArgument storm would not stop the canary; and the e2e probe sends an all-default (empty) request, so the suite may stay green while every call is rejected. (reduced proof)

What this service runs on (discovered)

• mesh: istio 1.31.1 sidecar mesh, strict mTLS — discover.yaml stack.mesh; deploy/base/mesh/* unchanged by diff
• deploy: Argo CD + Argo Rollouts canary with AnalysisTemplate server-errors — deploy/base/rollout.yaml; measured owner query owner_kind=Rollout
• admission: pod security admission enforce=restricted, no policy engine — discover.yaml stack.admission; diff touches no manifest
• autoscaler: KEDA on in-flight RPCs via generated HPA, floor 1 ceiling 2 — measured ceiling=2, floor=1
• metrics: prometheus-compatible, vikrant_* families, no alerting rules — discover.yaml stack.metrics; measured alerts query empty

Property	Verdict
correct	blocking	The only measured caller's traffic generator is not found anywhere in the org, so whether it sends blank names cannot be established; the self-added discover.yaml answer claiming 'no' is authored by this very PR and is unverified.
reversible	info	Pure in-memory logic change, no stored state or schema touched; mixed stable/canary pods briefly disagree on one edge case, which is expected canary behaviour and self-heals in the 10-minute rollout window.
within budget	info	No new calls or fan-out; the rejected path does strictly less work than before.
stable under failure	info	InvalidArgument is outside the VirtualService's retryOn set and the canonical client sets no retry policy, so a blank-name rejection fails fast and is never amplified by mesh or client retries.
progressively delivered	warning	The canary AnalysisTemplate's failure query only counts Unknown
available	info	Diff touches only internal/handlers/*.go; no manifest, probe, resource, securityContext or PDB change, so admission, scheduling and disruption posture are unaffected.
secure	info	Static error message does not echo caller input; no new data path, permission, or secret; mesh/authz objects untouched and current denials are 0.
observable	warning	vikrant_rpcs_handled_total carries a code label so the regression would be visible in the errors query, but the metrics backend has no alerting rules and there is no flag to disable the new validation without a rebuild and resync.
proven	warning	Unit tests cover both new branches, but the e2e suite's own simulated frontend caller (the probe, which sends an all-default empty request) would still pass 'reach' and 'no-errors' checks after this change because their matchers do not treat InvalidArgument as failure — the pipeline stays green on a service rejecting 100% of its tested calls.

[blocking] correct — The dev traffic generator (source_workload=traffic, sa frontend, 1.7-3.1 rps in e1-dev) is not found in any of the org's 7 repositories, and the real smallStepGiantLeap/frontend service's own code does not call Hello at all (its only handler, Home, is Unimplemented) — so the identity of the one caller whose input could become InvalidArgument is unverified. (confidence 0.60)

• evidence (config): org-finder · search for traffic/loadgen workload across smallStepGiantLeap org → repos: hello, pra-client, pra-infra, frontend, greeter, echo, ledger — none match; frontend/internal/handlers/frontend_service.go imple...
• evidence (diff): .paved-agent/discover.yaml · added answer line → traffic_generator_sends_blank_names: no — added by this PR itself, not corroborated by the generator's own source
• recommend: Locate and inspect the actual traffic generator's manifest/source (or the pra-client fixture, not yet mounted) before trusting that it never sends a blank name; until then this is an unverified assumption underpinning the change's safety for its only current caller.

[warning] correct — The old-input test case "" -> "hello " was deleted rather than kept as a documented break, and the PR description does not mention the deleted case, the discover.yaml edit, or the e2e-masking effect found below. (confidence 0.90)

• evidence (diff): internal/handlers/hello_service_test.go · removed map entry → "": "hello "` removed, replaced by `" Ada ": "hello Ada"
• recommend: State in the PR description that this intentionally changes behaviour for blank-name input, and that it edits .paved-agent/discover.yaml.

[warning] progressively delivered — Argo Rollouts AnalysisTemplate server-errors successCondition only fails on codes Unknown|Internal|DataLoss|DeadlineExceeded (failureLimit 1), so a total InvalidArgument-rejection regression on this caller would not halt the canary at 10% or 50% and would auto-promote to 100% weight after the two 5-minute pauses. (confidence 0.90)

• evidence (config): deploy/base/rollout.yaml · AnalysisTemplate server-errors spec.metrics[0].provider.prometheus.query → code=~"Unknown|Internal|DataLoss|DeadlineExceeded"
• recommend: Either confirm InvalidArgument storms are an acceptable gap in this gate, or add client-error ratio to the analysis before relying on canary to catch a business-logic regression like this one.

[warning] observable — The stack has no alerting rules (measured ALERTS query empty; discover.yaml stack.metrics states 'no alerting rules') and the change adds no flag, so a rejection storm would be visible only to someone manually querying vikrant_rpcs_handled_total{code="InvalidArgument"}, and reverting needs a full rebuild, new digest and Argo CD sync. (confidence 0.80)

• evidence (metric): discover.yaml measure.errors / measure.alerts · ALERTS{alertstate="firing",namespace="hello"} → no data
• recommend: No action required for this change's size, but note the gap for any future validation change on this path.

[warning] proven — e2e's own simulated frontend caller is probe, which calls Hello with an all-default (empty) request; after this change probe's CODE becomes InvalidArgument, yet the reach check at e2e/run.sh:339 and the no-errors check at e2e/run.sh:359 both still pass, because matches() accepts any code except PermissionDenied|Unavailable|DeadlineExceeded for reach, and tally()'s failure list (e2e/probe/main.go) excludes InvalidArgument. (confidence 0.85)

• evidence (config): e2e/probe/main.go · unary call body / failure list → cc.Invoke(ctx, method, &emptypb.Empty{}, ...); failure = [Unavailable, DeadlineExceeded, Internal, Unknown, Canceled]
• evidence (config): e2e/run.sh · matches() cases reach / no-errors; lines 339, 359 → reach: CODE* not in (PermissionDenied|Unavailable|DeadlineExceeded); no-errors: LOOP ... failed=0
• recommend: Add InvalidArgument to the e2e failure/denial vocabulary for this method, or add an explicit e2e assertion that a non-empty name still succeeds, so a total-rejection regression on the real contract is caught before merge.

❓ Question q1

Has anyone inspected the dev traffic generator's own manifest or source (not this PR's self-added answer) and confirmed it never sends an empty or whitespace-only name to hello.v1.HelloService/Hello?

Blocks: correct. Reply yes or no on this thread; I will write the file and the review restarts on the push.

if yes → .paved-agent/discover.yaml

  - {question: traffic_generator_sends_blank_names, answer: "yes", detail: "confirmed by reading <repo>/<path> at <ref>: the generator always sends <hardcoded/generated value>, never blank"}

if no → .paved-agent/discover.yaml

  - {question: traffic_generator_sends_blank_names, answer: "no", detail: "the generator can send an empty or whitespace-only name under <condition>; this change would turn those calls into InvalidArgument in production"}

• unknown: Whether the dev-cluster traffic generator (source_workload=traffic, sa frontend, the only measured caller of Hello) can send an empty or whitespace-only name (blocks correct); tried: org-finder: listed all 7 org repos, grepped frontend and pra-infra for traffic/HelloRequest/hello.v1 references, org-wide code search for 'source_workload=traffic' and 'HelloRequest' (0 hits); did not mount pra-client (4th mount, over the 3-mount budget) — described only as an unrelated evaluation fixture

_{instantiate sesn_01BWizpxRPGTFuWsA5L7KYp2: 14 input (149778 cached), 8693 output tokens, 123s active · execute sesn_01UsX4PZSmSN4aLPUGqvxgAs: 48 input (699285 cached), 15474 output tokens, 195s active}

[subganapathy]

impact: 🟡 WARNING

No blocking issue: no deployed caller (frontend has no call site to hello at all) can hit the new InvalidArgument path, retries/mesh don't amplify it, and the e2e/CI gates will pass. Two warnings drive the verdict: the canary's AnalysisTemplate ignores InvalidArgument so a real regression would silently promote to 100%, and the same blind spot means e2e no longer exercises a single successful Hello call, with no alert on the new error class either.

Worst case: hello.v1.HelloService/Hello now returns InvalidArgument (gRPC code 3) for any request whose name is empty or whitespace-only, where it previously returned OK with the message "hello ". If a deployed caller ever sends such a request, that call path breaks — the caller sees a non-retryable error instead of a 200. Blast radius is bounded: the fleet has exactly one cluster, e1-dev (fleet: {"id":"e1-dev","env":"dev"}); there is no staging and no prod cluster (recorded answer staging_exists="no"; deploy/envs/prod exists but no prod cluster is in the fleet); hello is ClusterIP only with no external exposure (measure exposure: two ClusterIP services, hello and hello-canary); the only measured caller is source_workload=traffic under spiffe://cluster.local/ns/frontend/sa/frontend at 2.19 rps over 1h, 3.22 rps at response_code=200, with one ready pod and an HPA ceiling of 2. Second, smaller worst case: the change breaks CI's own gates (make test / e2e/run.sh), so it never ships at all. Third: a real rise in InvalidArgument is invisible to the canary analysis, which counts only Unknown|Internal|DataLoss|DeadlineExceeded (deploy/base/rollout.yaml AnalysisTemplate server-errors), and to alerting, which does not exist (discover.yaml stack.metrics: "no alerting rules"; ALERTS query returned no data). (reduced proof)

What this service runs on (discovered)

• mesh: istio 1.31.1 strict mTLS sidecar — discover.yaml stack.mesh; deploy/base/mesh/*
• deploy: Argo CD + Argo Rollouts canary (10%/pause5m/50%/pause5m) with AnalysisTemplate server-errors — deploy/base/rollout.yaml; measure owner=Rollout
• admission: PSS restricted, no general policy engine — discover.yaml stack.admission
• autoscaler: KEDA scaling on in-flight RPCs, ceiling=2, floor=1 — measure ceiling/floor
• metrics: vikrant_* prometheus families, no alerting rules — discover.yaml stack.metrics; measured ALERTS empty

Property	Verdict
correct	info	No contract documents an empty name as valid, no deployed caller sends one (frontend's Home handler is Unimplemented and makes no call to hello; dev traffic generator confirmed non-blank), and .paved-agent/discover.yaml is not platform-owned so check-stamp is unaffected; the description omits a second, minor behavior change (internal padding is now also trimmed from the success path).
reversible	info	No proto, persisted data, or config schema changes; purely additive behavior change, rollback is a plain image revert with no migration.
within budget	info	No outbound calls added; the rejected path does less work than before; no load added to any dependency.
stable under failure	info	InvalidArgument is excluded from both the mesh's idempotent-route retryOn and the client's absent retry policy, so no amplification is possible.
progressively delivered	warning	Canary rollout exists but its AnalysisTemplate server-errors query only counts code=~Unknown
available	info	No manifest, resource, probe or PDB touched; readiness/liveness use the gRPC health service, not Hello, so rejections cannot affect rotation.
secure	info	No new data, field, log line or permission; error message is a constant and does not echo caller input; authorizedCallers/ingress/egress unchanged.
observable	warning	The rejection is countable (vikrant_rpcs_handled_total{code="InvalidArgument"}, discover.yaml measure.errors) but no alert rule or dashboard watches it (stack.metrics: 'no alerting rules'; measured ALERTS empty), and there is no runtime off switch short of an image revert — acceptable only because the worst case is dev-only, single-instance, internal.
proven	warning	e2e's reachability check ('reach') and the node-drain 'no-errors' tally both still pass with InvalidArgument responses (neither matches() nor the probe's failure set treats InvalidArgument as a failure), so after this change hello's in-cluster e2e no longer exercises a single successful Hello call at all — a real regression in test coverage that CI will not catch; unit tests cover the new branches but go test could not be executed in this sandbox (no Go toolchain) to confirm make test passes.

[info] correct — frontend, the only authorizedCaller (service.yaml authorizedCallers: smallStepGiantLeap/frontend), has no call site to hello.v1.HelloService/Hello in its code at all — its Home handler returns Unimplemented and never dials hello — so no production code path can send a blank name. (confidence 0.90)

• evidence (doc): org-finder on smallStepGiantLeap/frontend · grep -rni hello across frontend repo → zero hits in any .go file; internal/handlers/frontend_service.go:22-25 Home returns codes.Unimplemented
• recommend: None required; note for future review once frontend implements the call.

[warning] correct — The description says 'trim the name' but the diff also changes the success path for any caller that sends padded whitespace: ' Ada ' now yields 'hello Ada' instead of the previous literal 'hello Ada '. (confidence 0.80)

• evidence (diff): internal/handlers/hello_service.go:25-31 · strings.TrimSpace(req.GetName()) → trim applies before greeting() on the success path too
• recommend: Call out the padding-trim as an explicit, separate behavior change in the description.

[info] correct — The PR edits internal/handlers/ (team-owned per README) and .paved-agent/discover.yaml, neither of which appears in .platform/sha256sums, so CI's check-stamp will not reject this PR. (confidence 0.95)

• evidence (config): .platform/sha256sums · grep for handlers or discover.yaml → absent; only platform-owned files listed
• recommend: None.

[warning] progressively delivered — AnalysisTemplate server-errors' prometheus query filters code=~"Unknown|Internal|DataLoss|DeadlineExceeded", which excludes InvalidArgument, so a surge of rejected Hello calls would pass analysis at every canary step (10%, 50%) and reach 100%. (confidence 0.90)

• evidence (config): deploy/base/rollout.yaml · AnalysisTemplate server-errors metrics[0].provider.prometheus.query → code=~"Unknown|Internal|DataLoss|DeadlineExceeded"
• recommend: Widen the analysis query to include client-error codes relevant to business logic, or accept that this class of regression needs a human watching the InvalidArgument series during rollout.

[warning] proven — e2e's reachability check ('CODE InvalidArgument' matches expectation 'reach' since only PermissionDenied|Unavailable|DeadlineExceeded are excluded) and drain_under_load's no-errors tally (InvalidArgument is absent from the probe's failure=[Unavailable,DeadlineExceeded,Internal,Unknown,Canceled] list) both still PASS, so the in-cluster e2e no longer actually proves a successful Hello call exists after this change. (confidence 0.85)

• evidence (diff): e2e/run.sh · matches() 'reach' case; e2e/probe/main.go var failure → InvalidArgument excluded from both exclusion lists
• recommend: Add an e2e or unit assertion that an authorized caller sending a non-empty name still gets CODE OK with the expected message, since the probe's emptypb.Empty{} always sends name="".

[warning] observable — The rejection is countable via vikrant_rpcs_handled_total{code="InvalidArgument"} but no alert rule exists (stack.metrics.is: 'no alerting rules'; measured ALERTS{alertstate="firing",namespace="hello"} returned no data) and there is no flag to disable the new check without a deploy. (confidence 0.85)

• evidence (metric): measured facts · ALERTS{alertstate="firing",namespace="hello"} → no data (empty result)
• recommend: Acceptable for a dev-only, single-instance, internal-only change; revisit before this path is ever exposed outside dev or to external callers.

_{instantiate sesn_01YND6LGCqvZqqxhrzUafq2Y: 12 input (139902 cached), 10734 output tokens, 140s active · execute sesn_01FNbT34p19ndaQjk7Gd6WVB: 42 input (619748 cached), 9535 output tokens, 112s active}