diff --git a/apps/server/src/main/kotlin/com/correx/apps/server/Main.kt b/apps/server/src/main/kotlin/com/correx/apps/server/Main.kt
index 8f433214..ca648ca8 100644
--- a/apps/server/src/main/kotlin/com/correx/apps/server/Main.kt
+++ b/apps/server/src/main/kotlin/com/correx/apps/server/Main.kt
@@ -344,9 +344,12 @@ fun main() {
         ),
     )
 
+    val observationStore = InfrastructureModule.createObservationStore()
     val wsToolRegistryProvider = WorkspaceToolRegistryProvider { workspace ->
         val wsRegistry = InfrastructureModule.createToolRegistry(
-            buildToolConfigForWorkspace(workspace, shellAllowedExecutables, toolsConfig, researchToolConfig),
+            buildToolConfigForWorkspace(
+                workspace, shellAllowedExecutables, toolsConfig, researchToolConfig, observationStore,
+            ),
             extraTools = extraTools,
         )
         val wsExecutor = DispatchingToolExecutor(wsRegistry)
@@ -390,7 +393,6 @@ fun main() {
         semanticReviewer = SemanticReviewerImpl(inferenceRouter),
     )
     val decisionJournalRepository = InfrastructureModule.createDecisionJournalRepository(eventStore)
-    val observationStore = InfrastructureModule.createObservationStore()
     val defaultOrchestrationConfig = OrchestrationConfig(
         sandboxRoot = sandboxRoot,
         defaultSystemPromptPath = toolsConfig.defaultSystemPromptPath,
@@ -963,6 +965,7 @@ private fun buildToolConfigForWorkspace(
     shellAllowedExecutables: Set<String>,
     toolsConfig: com.correx.core.config.ToolsConfig,
     research: com.correx.infrastructure.tools.ResearchToolConfig,
+    observationStore: com.correx.core.context.observation.ObservationStore? = null,
 ): ToolConfig = ToolConfig(
     research = research,
     shell = ShellConfig(
@@ -974,6 +977,8 @@ private fun buildToolConfigForWorkspace(
         enabled = toolsConfig.fileReadEnabled,
         allowedPaths = workspace.allowedPaths,
         workingDir = workspace.workingDir,
+        observationStore = observationStore,
+        repoRoot = workspace.workingDir?.toString(),
     ),
     fileWrite = FileWriteConfig(
         enabled = toolsConfig.fileWriteEnabled,
diff --git a/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorConcepts.kt b/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorConcepts.kt
index 090a45d9..88c2ae3e 100644
--- a/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorConcepts.kt
+++ b/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorConcepts.kt
@@ -4,8 +4,12 @@ import com.correx.core.context.model.ContextEntry
 import com.correx.core.context.model.ContextLayer
 import com.correx.core.context.model.EntryRole
 import com.correx.core.events.events.ConceptPromotedEvent
+import com.correx.core.events.events.RetryAttemptedEvent
+import com.correx.core.events.events.StoredEvent
 import com.correx.core.events.types.ContextEntryId
+import com.correx.core.events.types.StageId
 import com.correx.core.kernel.concept.ConceptCompilerProjection
+import com.correx.core.kernel.concept.conceptClassKey
 import com.correx.core.transitions.graph.StageConfig
 import java.util.UUID
 
@@ -66,4 +70,51 @@ internal suspend fun SessionOrchestrator.promotedConceptEntries(stageConfig: Sta
     }
 }
 
+/**
+ * Store 2 fix-confidence lifecycle (docs/plans/2026-07-21-acr-knowledge-accretion.md §Store 2): a
+ * classKey below the hard-promotion threshold isn't silence — [ConceptCompilerProjection] already
+ * tracks it as `unconfirmed` (validatedFixes 1..threshold-1) or `falsified` (contradicted). Reactively
+ * matched against the CURRENT retry's own classKey (same normalization the compiler uses) and
+ * delivered as a soft, one-shot hint (or steer-away) BEFORE the cluster earns hard promotion. Once
+ * `classKey` is in [state.promoted][com.correx.core.kernel.concept.ConceptCompilerState.promoted] the
+ * hard-promoted delivery ([promotedConceptEntries]) already covers it, so this is skipped to avoid
+ * double delivery.
+ */
+internal suspend fun SessionOrchestrator.unconfirmedFixEntries(
+    sessionEvents: List<StoredEvent>,
+    stageId: StageId,
+): List<ContextEntry> {
+    val latest = sessionEvents.mapNotNull { it.payload as? RetryAttemptedEvent }.lastOrNull { it.stageId == stageId }
+    val sig = latest?.failureReason?.lineSequence()?.firstOrNull()?.take(SIGNATURE_MAX)?.trim().orEmpty()
+    val classKey = latest?.let { conceptClassKey(it.gate, sig) }
+    val projection = ConceptCompilerProjection()
+    val state = eventStore.allEvents().fold(projection.initial(), projection::apply)
+    val cluster = classKey?.takeIf { it !in state.promoted }?.let { state.clusters[it] }
+    val content = when {
+        cluster == null -> null
+        cluster.contradicted ->
+            "## Steer away from a known dead end\nA prior attempt at this exact failure class " +
+                "(${cluster.signature}) was tried before and a later failure showed it did NOT hold. " +
+                "Do not repeat that approach — find a materially different fix."
+        cluster.validatedFixes >= 1 ->
+            "## Unconfirmed prior fix (validated ${cluster.validatedFixes}x, not yet settled)\n" +
+                "This failure class (${cluster.signature}) was resolved before" +
+                (cluster.fixPath?.let { " in `$it`" } ?: "") + " — worth trying first, but it hasn't " +
+                "recurred enough times across sessions to be a certain fix here. Verify it actually applies."
+        else -> null
+    } ?: return emptyList()
+    return listOf(
+        ContextEntry(
+            id = ContextEntryId(UUID.randomUUID().toString()),
+            layer = ContextLayer.L1,
+            content = content,
+            sourceType = "unconfirmedFix",
+            sourceId = classKey.orEmpty(),
+            tokenEstimate = estimateTokens(content),
+            role = EntryRole.USER,
+        ),
+    )
+}
+
+private const val SIGNATURE_MAX = 200
 private const val MAX_PROMOTED_CONCEPTS = 3
diff --git a/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorExecution.kt b/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorExecution.kt
index 94af0b58..796086f9 100644
--- a/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorExecution.kt
+++ b/core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestratorExecution.kt
@@ -245,6 +245,9 @@ internal suspend fun SessionOrchestrator.executeStage(
         ?.let { listOf(it) } ?: emptyList()
     val recoveryTicketEntries = buildRecoveryTicketEntry(sessionEvents, stageId)
         ?.let { listOf(it) } ?: emptyList()
+    // Store 2 soft-confidence lifecycle (below hard-promotion threshold): reactive hint/steer-away
+    // matched to THIS retry's own classKey, see unconfirmedFixEntries.
+    val unconfirmedFixHints = unconfirmedFixEntries(sessionEvents, stageId)
     val vocabularyEntries = artifactKindRegistry
         ?.takeIf { stageConfig.metadata["injectArtifactKinds"] == "true" }
         ?.let { listOf(buildArtifactKindVocabularyEntry(it.list())) } ?: emptyList()
@@ -282,7 +285,7 @@ internal suspend fun SessionOrchestrator.executeStage(
             journalEntries + repoMapEntries + claimedTaskEntries +
             needsEntries + schemaEntries + vocabularyEntries + promptEntries + steeringEntries +
             rejectionEntries + clarificationEntries + retryFeedbackEntries + groundingFeedbackEntries +
-            recoveryTicketEntries + remainingDeltaEntries,
+            recoveryTicketEntries + unconfirmedFixHints + remainingDeltaEntries,
     )
     val contextPack = runCatching {
         contextPackBuilder.build(
diff --git a/infrastructure/tools/build.gradle b/infrastructure/tools/build.gradle
index c9dc23c3..55540369 100644
--- a/infrastructure/tools/build.gradle
+++ b/infrastructure/tools/build.gradle
@@ -17,6 +17,7 @@ dependencies {
     implementation project(":infrastructure:tools:filesystem")
     implementation project(":core:artifacts")
     implementation project(":core:artifacts-store")
+    implementation project(":core:context")
 
     // Web research tools (web_search, web_fetch) + deterministic HTML→markdown extraction.
     implementation 'org.jsoup:jsoup:1.20.1'
diff --git a/infrastructure/tools/filesystem/build.gradle b/infrastructure/tools/filesystem/build.gradle
index 5190029e..8a04f7da 100644
--- a/infrastructure/tools/filesystem/build.gradle
+++ b/infrastructure/tools/filesystem/build.gradle
@@ -10,6 +10,8 @@ dependencies {
     implementation project(':core:approvals')
     implementation project(':core:artifacts')
     implementation project(':core:artifacts-store')
+    implementation project(':core:context')
+    implementation project(':core:sourcedesc')
     implementation 'org.slf4j:slf4j-api:2.0.16'
 }
 
diff --git a/infrastructure/tools/filesystem/src/main/kotlin/com/correx/infrastructure/tools/filesystem/FileReadTool.kt b/infrastructure/tools/filesystem/src/main/kotlin/com/correx/infrastructure/tools/filesystem/FileReadTool.kt
index 9c5c6277..9aa4f2e1 100644
--- a/infrastructure/tools/filesystem/src/main/kotlin/com/correx/infrastructure/tools/filesystem/FileReadTool.kt
+++ b/infrastructure/tools/filesystem/src/main/kotlin/com/correx/infrastructure/tools/filesystem/FileReadTool.kt
@@ -1,7 +1,10 @@
 package com.correx.infrastructure.tools.filesystem
 
 import com.correx.core.approvals.Tier
+import com.correx.core.context.observation.Observation
+import com.correx.core.context.observation.ObservationStore
 import com.correx.core.events.events.ToolRequest
+import com.correx.core.sourcedesc.describe
 import com.correx.core.tools.compression.CompressionRule.StripBlankLines
 import com.correx.core.tools.compression.CompressionRule.StripLeadingWhitespace
 import com.correx.core.tools.compression.DeclarativeCompressor
@@ -32,6 +35,12 @@ import kotlin.io.path.name
 class FileReadTool(
     private val allowedPaths: Set<Path> = emptySet(),
     private val workingDir: Path? = null,
+    // ACR Store 1 (docs/plans/2026-07-21-acr-knowledge-accretion.md): primes the cross-session
+    // observation cache on a whole-file read, not just on write, so a later describeCached lookup
+    // (SessionOrchestratorArtifacts.kt) for this exact content hash is already warm. Both null by
+    // default — no-op unless a workspace wiring supplies them.
+    private val observationStore: ObservationStore? = null,
+    private val repoRoot: String? = null,
 ) : Tool, ToolExecutor {
 
     // Resolve relative paths against the bound workspace's working dir, NOT the JVM
@@ -140,7 +149,7 @@ class FileReadTool(
         }
     }
 
-    private fun readFile(path: Path, startLine: Int?, endLine: Int?, request: ToolRequest): ToolResult = runCatching {
+    private suspend fun readFile(path: Path, startLine: Int?, endLine: Int?, request: ToolRequest): ToolResult = runCatching {
         // Read the file once. Lines and the (whole-read) content hash both derive from these bytes,
         // so a full read no longer hits the disk twice (readAllLines + readAllBytes for the hash).
         val bytes = Files.readAllBytes(path)
@@ -169,7 +178,9 @@ class FileReadTool(
         // against what the agent actually saw. A partial or truncated view establishes no baseline —
         // the agent must read the relevant range before editing.
         val sawWholeFile = startLine == null && endLine == null && !lineCapped && !charCapped
-        val metadata = if (sawWholeFile) mapOf("contentHash" to sha256(bytes)) else emptyMap()
+        val hash = if (sawWholeFile) sha256(bytes) else null
+        val metadata = hash?.let { mapOf("contentHash" to it) } ?: emptyMap()
+        hash?.let { primeObservation(path, bytes, it) }
         ToolResult.Success(
             invocationId = request.invocationId,
             output = content + note,
@@ -183,6 +194,17 @@ class FileReadTool(
         )
     }
 
+    /** No-op unless both [observationStore] and [repoRoot] are wired; skips if already cached for this hash. */
+    private suspend fun primeObservation(path: Path, bytes: ByteArray, hash: String) {
+        val store = observationStore ?: return
+        val root = repoRoot ?: return
+        val relPath = workingDir?.let { runCatching { it.relativize(path).toString() }.getOrNull() } ?: path.toString()
+        val cached = store.get(root, relPath)
+        if (cached?.contentHash == hash) return
+        val rendered = describe(relPath, bytes).render().takeIf { it.isNotBlank() }
+        store.put(Observation(root, relPath, hash, rendered, System.currentTimeMillis()))
+    }
+
     private fun sha256(bytes: ByteArray): String =
         java.security.MessageDigest.getInstance("SHA-256").digest(bytes)
             .joinToString("") { "%02x".format(it) }
diff --git a/infrastructure/tools/filesystem/src/test/kotlin/com/correx/infrastructure/tools/filesystem/FileReadToolTest.kt b/infrastructure/tools/filesystem/src/test/kotlin/com/correx/infrastructure/tools/filesystem/FileReadToolTest.kt
index 1110784e..e5ef6dd6 100644
--- a/infrastructure/tools/filesystem/src/test/kotlin/com/correx/infrastructure/tools/filesystem/FileReadToolTest.kt
+++ b/infrastructure/tools/filesystem/src/test/kotlin/com/correx/infrastructure/tools/filesystem/FileReadToolTest.kt
@@ -1,5 +1,6 @@
 package com.correx.infrastructure.tools.filesystem
 
+import com.correx.core.context.observation.InMemoryObservationStore
 import com.correx.core.events.events.ToolRequest
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
@@ -193,6 +194,24 @@ class FileReadToolTest {
         assertTrue((result as ToolResult.Success).metadata["contentHash"] != null)
     }
 
+    @Test
+    fun `execute primes the observation store for a whole-file read`(): Unit = runBlocking {
+        val tempFile = Files.createTempFile("test_prime", ".kt")
+        Files.writeString(tempFile, "fun foo() {}")
+        val store = InMemoryObservationStore()
+        val tool = FileReadTool(
+            allowedPaths = setOf(tempFile.parent),
+            workingDir = tempFile.parent,
+            observationStore = store,
+            repoRoot = "repoA",
+        )
+
+        tool.execute(createRequest(tempFile.toString()))
+
+        val observed = store.get("repoA", tempFile.fileName.toString())
+        assertTrue(observed != null)
+    }
+
     @Test
     fun `outputCompressor strips blank lines and leading whitespace`() {
         val tool = FileReadTool()
diff --git a/infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/ToolConfig.kt b/infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/ToolConfig.kt
index d1a53945..313920ed 100644
--- a/infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/ToolConfig.kt
+++ b/infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/ToolConfig.kt
@@ -1,5 +1,6 @@
 package com.correx.infrastructure.tools
 
+import com.correx.core.context.observation.ObservationStore
 import com.correx.core.tools.contract.Tool
 import com.correx.infrastructure.tools.filesystem.FileDeleteTool
 import com.correx.infrastructure.tools.filesystem.FileEditTool
@@ -39,6 +40,9 @@ data class FileReadConfig(
     val enabled: Boolean = false,
     val allowedPaths: Set<Path> = emptySet(),
     val workingDir: Path? = null,
+    // ACR Store 1 hot-path priming (docs/plans/2026-07-21-acr-knowledge-accretion.md); both null is a no-op.
+    val observationStore: ObservationStore? = null,
+    val repoRoot: String? = null,
 )
 data class FileWriteConfig(
     val enabled: Boolean = false,
@@ -75,6 +79,8 @@ fun ToolConfig.buildTools(): List<Tool> = buildList {
             FileReadTool(
                 allowedPaths = fileRead.allowedPaths,
                 workingDir = fileRead.workingDir,
+                observationStore = fileRead.observationStore,
+                repoRoot = fileRead.repoRoot,
             ),
         )
         // list_dir is read-only enumeration; shares the reader's jail + anchor and the same toggle.