Say a failed test's whole output on the Go and Node build modules' own log streams, kept 14 days and 2 GiB, and read it with build_go_log and build_node_log, so a cut verdict's cause is read, not guessed

modules/mesh-build-go/cmd/mesh-build-go/asks.go

@@ -47,6 +47,9 @@ func (m *Module) askSteps(steps []StepTool) buildstep.AskSteps {
 		Has:     m.Has,
 		Release: func(ws string) error { return m.spaces().Release(ws) },
 		Logf:    m.Say,
+		// A failed test's whole output is said on the module's own log stream (buildstep.LogTool reads it back).
+		Narrate: m.Emit,
+		Module:  "mesh-build-go",
 	}
 }
 

modules/mesh-build-go/cmd/mesh-build-go/emit_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"os"
 	"path/filepath"
 	"slices"
@@ -47,9 +48,14 @@ func TestTheManifestDeclaresTheToolchainsStream(t *testing.T) {
 		Streams []struct {
 			Name   string   `json:"name"`
 			Events []string `json:"events"`
+			Age    int      `json:"max-age-days"`
+			MiB    int      `json:"max-mib"`
 		} `json:"streams"`
 	}
-	if err := json.Unmarshal(raw, &m); err != nil || len(m.Streams) != 1 || m.Streams[0].Name != "toolchains-go" || !slices.Equal(m.Streams[0].Events, []string{"toolchain.**"}) {
+	// And its log stream: a failed test's whole output, kept 14 days and at most 2 GiB, dropping its oldest (the operator,
+	// 2026-10-30).
+	if err := json.Unmarshal(raw, &m); err != nil || len(m.Streams) != 2 || m.Streams[0].Name != "toolchains-go" || !slices.Equal(m.Streams[0].Events, []string{"toolchain.**"}) ||
+		m.Streams[1].Name != buildstep.LogStreamOf("go") || !slices.Equal(m.Streams[1].Events, []string{"log.**"}) || m.Streams[1].Age != 14 || m.Streams[1].MiB != 2048 {
 		t.Errorf("streams = %+v (%v)", m.Streams, err)
 	}
 }

modules/mesh-build-go/cmd/mesh-build-go/main.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
@@ -41,6 +42,7 @@ func main() {
 		Emit:                func(t string, b any) error { return stdio.Emit(t, b) },
 		Steps:               stdio.State(delivery.StepsState).Put,
 		ReadSteps:           readOf(stdio.State(delivery.StepsState)),
+		ReadLog:             stdio.Stream(buildstep.LogStreamOf("go")).Read,
 		Pauses:              stdio.State(delivery.PausesState).Put,
 		ReadPauses:          readOf(stdio.State(delivery.PausesState)),
 		ReadToolchainsState: readOf(stdio.State(delivery.ToolchainsState)),

modules/mesh-build-go/cmd/mesh-build-go/module.go

@@ -31,6 +31,9 @@ type Module struct {
 	// Held is the puller whose running asks a step-end tool will not end (issue 1890); nil in a test.
 	Held                           *buildstep.Puller
 	ReadSteps, ReadToolchainsState StateRead
+	// ReadLog reads the module's own log stream (stdio.Stream(buildstep.LogStreamOf(language)).Read), where each step
+	// says a failed test's whole output (Emit says it); nil in a test.
+	ReadLog buildstep.StreamRead
 	// Pauses is the Put of the pauses state, which keeps the node's pause key without an age; ReadPauses reads it back.
 	Pauses     buildstep.Put
 	ReadPauses StateRead

modules/mesh-build-go/cmd/mesh-build-go/module_test.go

@@ -115,7 +115,7 @@ func TestAGoThatCannotBeRunRefusesEveryStepAndHealthIsUnhealthy(t *testing.T) {
 		{Name: "short_probe", Run: run},
 	}, m.StepTools()...)
 	for _, tool := range m.Tools(steps) {
-		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == StepEndTool {
+		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == LogReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == StepEndTool {
 			continue
 		}
 		var reason string

modules/mesh-build-go/cmd/mesh-build-go/read.go

@@ -15,13 +15,16 @@ import (
 	"time"
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 // The read tools, named as the module is: build_go_ and the verb.
 const (
-	StepReadTool       = "build_go_step"
+	StepReadTool  = "build_go_step"
-	StepsReadTool      = "build_go_steps"
+	StepsReadTool = "build_go_steps"
+	// LogReadTool reads one step's log, a failed test's whole output, from the module's own log stream.
+	LogReadTool        = "build_go_log"
 	ToolchainsReadTool = "build_go_toolchains"
 )
 
@@ -225,7 +228,14 @@ func (m *Module) ReadToolchains() (map[string]delivery.Toolchain, error) {
 
 // ReadTools are the module's read tools. All are read-only.
 func (m *Module) ReadTools() []stdio.Tool {
+	readLog := m.ReadLog
+	if readLog == nil {
+		readLog = func(string, uint64, int) (*stdio.StreamPage, error) {
+			return nil, fmt.Errorf("this process reads no log stream: it was not launched by the runtime")
+		}
+	}
 	return []stdio.Tool{
+		buildstep.LogTool(LogReadTool, readLog),
 		{Name: StepReadTool,
 			Description: "What one step of this machine ended with, as stored in the module's steps state: its tool, state " +
 				"(running, passed, failed, refused), when it started and ended, why it failed or was refused, and its result " +

modules/mesh-build-go/go.mod

@@ -3,7 +3,7 @@ module meshbuildgo
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde
 	github.com/distribution/distribution/v3 v3.1.2
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0

modules/mesh-build-go/go.sum

@@ -1,5 +1,11 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771 h1:Tt16HJk8JZRce1i3JzzDSNdCWOrv7dw8FQ/bckNQ5Ig=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095131-16bc0dcf3e9d h1:jFOz6wUfZvIayd4DctwlaFKKZHQNME6NLs2OS1rNv30=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095131-16bc0dcf3e9d/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095816-530d8d3007dc h1:Wdjl2gomooHswJ5qpkwZPq/ureZgXVw6FMCsgzPJhPo=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095816-530d8d3007dc/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde h1:eKXSllHCS31GgMazfvZ7BeiLoXIUibnUmzxWVkj+Vcw=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/alicebob/miniredis/v2 v2.35.0 h1:QwLphYqCEAo1eu1TqPRN2jgVMPBweeQcR21jeqDCONI=
 github.com/alicebob/miniredis/v2 v2.35.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=

modules/mesh-build-go/module.json

@@ -51,6 +51,7 @@
     "build_go_release",
     "build_go_step",
     "build_go_steps",
+    "build_go_log",
     "build_go_step_end",
     "build_go_toolchains",
     "build_go_status",
@@ -60,6 +61,12 @@
     {
       "name": "toolchains-go",
       "events": ["toolchain.**"]
+    },
+    {
+      "name": "go-build-logs",
+      "events": ["log.**"],
+      "max-age-days": 14,
+      "max-mib": 2048
     }
   ],
   "requires": [

modules/mesh-build-node/.gitignore

@@ -0,0 +1 @@
+/mesh-build-node

modules/mesh-build-node/cmd/mesh-build-node/asks.go

@@ -37,6 +37,9 @@ func (m *Module) askSteps(steps []StepTool) buildstep.AskSteps {
 		},
 		Release: func(ws string) error { return m.spaces().Release(ws) },
 		Logf:    m.Say,
+		// A failed test's whole output is said on the module's own log stream (buildstep.LogTool reads it back).
+		Narrate: m.Emit,
+		Module:  "mesh-build-node",
 	}
 }
 

modules/mesh-build-node/cmd/mesh-build-node/emit_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"os"
 	"path/filepath"
 	"slices"
@@ -47,9 +48,14 @@ func TestTheManifestDeclaresTheToolchainsStream(t *testing.T) {
 		Streams []struct {
 			Name   string   `json:"name"`
 			Events []string `json:"events"`
+			Age    int      `json:"max-age-days"`
+			MiB    int      `json:"max-mib"`
 		} `json:"streams"`
 	}
-	if err := json.Unmarshal(raw, &m); err != nil || len(m.Streams) != 1 || m.Streams[0].Name != "toolchains-node" || !slices.Equal(m.Streams[0].Events, []string{"toolchain.**"}) {
+	// And its log stream: a failed test's whole output, kept 14 days and at most 2 GiB, dropping its oldest (the operator,
+	// 2026-10-30).
+	if err := json.Unmarshal(raw, &m); err != nil || len(m.Streams) != 2 || m.Streams[0].Name != "toolchains-node" || !slices.Equal(m.Streams[0].Events, []string{"toolchain.**"}) ||
+		m.Streams[1].Name != buildstep.LogStreamOf("node") || !slices.Equal(m.Streams[1].Events, []string{"log.**"}) || m.Streams[1].Age != 14 || m.Streams[1].MiB != 2048 {
 		t.Errorf("streams = %+v (%v)", m.Streams, err)
 	}
 }

modules/mesh-build-node/cmd/mesh-build-node/main.go

@@ -16,6 +16,7 @@ import (
 	"time"
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/forgekey"
 )
@@ -47,6 +48,7 @@ func main() {
 		Emit:                func(t string, b any) error { return stdio.Emit(t, b) },
 		Steps:               stdio.State(delivery.StepsState).Put,
 		ReadSteps:           readOf(stdio.State(delivery.StepsState)),
+		ReadLog:             stdio.Stream(buildstep.LogStreamOf("node")).Read,
 		Pauses:              stdio.State(delivery.PausesState).Put,
 		ReadPauses:          readOf(stdio.State(delivery.PausesState)),
 		ReadToolchainsState: readOf(stdio.State(delivery.ToolchainsState)),

modules/mesh-build-node/cmd/mesh-build-node/module.go

@@ -45,6 +45,9 @@ type Module struct {
 	// Held is the puller whose running asks a step-end tool will not end (issue 1890); nil in a test.
 	Held                           *buildstep.Puller
 	ReadSteps, ReadToolchainsState StateRead
+	// ReadLog reads the module's own log stream (stdio.Stream(buildstep.LogStreamOf(language)).Read), where each step
+	// says a failed test's whole output (Emit says it); nil in a test.
+	ReadLog buildstep.StreamRead
 	// Pauses is the Put of the pauses state, which keeps the node's pause key without an age; ReadPauses reads it back.
 	Pauses     buildstep.Put
 	ReadPauses StateRead

modules/mesh-build-node/cmd/mesh-build-node/module_test.go

@@ -117,7 +117,7 @@ func TestANodeThatCannotBeRunRefusesEveryStepAndHealthIsUnhealthy(t *testing.T)
 		{Name: "short_probe", Run: run},
 	}, (&Module{}).StepTools()...)
 	for _, tool := range m.Tools(steps) {
-		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == StepEndTool {
+		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == LogReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == StepEndTool {
 			continue
 		}
 		var reason string

modules/mesh-build-node/cmd/mesh-build-node/read.go

@@ -15,13 +15,16 @@ import (
 	"time"
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 // The read tools, named as the module is: build_node_ and the verb.
 const (
-	StepReadTool       = "build_node_step"
+	StepReadTool  = "build_node_step"
-	StepsReadTool      = "build_node_steps"
+	StepsReadTool = "build_node_steps"
+	// LogReadTool reads one step's log, a failed test's whole output, from the module's own log stream.
+	LogReadTool        = "build_node_log"
 	ToolchainsReadTool = "build_node_toolchains"
 )
 
@@ -225,7 +228,14 @@ func (m *Module) ReadToolchains() (map[string]delivery.Toolchain, error) {
 
 // ReadTools are the module's read tools. All are read-only.
 func (m *Module) ReadTools() []stdio.Tool {
+	readLog := m.ReadLog
+	if readLog == nil {
+		readLog = func(string, uint64, int) (*stdio.StreamPage, error) {
+			return nil, fmt.Errorf("this process reads no log stream: it was not launched by the runtime")
+		}
+	}
 	return []stdio.Tool{
+		buildstep.LogTool(LogReadTool, readLog),
 		{Name: StepReadTool,
 			Description: "What one step of this machine ended with, as stored in the module's steps state: its tool, state " +
 				"(running, passed, failed, refused), when it started and ended, why it failed or was refused, and its result " +

modules/mesh-build-node/go.mod

@@ -3,7 +3,7 @@ module meshbuildnode
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde
 	github.com/distribution/distribution/v3 v3.1.2
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-build-node/go.sum

@@ -1,5 +1,11 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771 h1:Tt16HJk8JZRce1i3JzzDSNdCWOrv7dw8FQ/bckNQ5Ig=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261029233535-78c9ec881771/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095131-16bc0dcf3e9d h1:jFOz6wUfZvIayd4DctwlaFKKZHQNME6NLs2OS1rNv30=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095131-16bc0dcf3e9d/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095816-530d8d3007dc h1:Wdjl2gomooHswJ5qpkwZPq/ureZgXVw6FMCsgzPJhPo=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030095816-530d8d3007dc/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde h1:eKXSllHCS31GgMazfvZ7BeiLoXIUibnUmzxWVkj+Vcw=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030100935-c2ec8b6b2fde/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/alicebob/miniredis/v2 v2.35.0 h1:QwLphYqCEAo1eu1TqPRN2jgVMPBweeQcR21jeqDCONI=
 github.com/alicebob/miniredis/v2 v2.35.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=

modules/mesh-build-node/module.json

@@ -46,6 +46,7 @@
     "build_node_release",
     "build_node_step",
     "build_node_steps",
+    "build_node_log",
     "build_node_step_end",
     "build_node_toolchains",
     "build_node_status",
@@ -57,6 +58,12 @@
       "events": [
         "toolchain.**"
       ]
+    },
+    {
+      "name": "node-build-logs",
+      "events": ["log.**"],
+      "max-age-days": 14,
+      "max-mib": 2048
     }
   ],
   "requires": [