From f6da5ded83bcf62abea44715bb6bdde30710a573 Mon Sep 17 00:00:00 2001
From: Mark IJbema <mark@kilocode.ai>
Date: Tue, 24 Feb 2026 13:00:54 +0100
Subject: [PATCH] refactor: move dynamic editor context from system prompt to
 user message

Split editor context into static and dynamic parts:

- Static (system prompt, cached): date, timezone, shell
  These rarely change and benefit from prompt caching.

- Dynamic (user message, per-turn): active file, visible files, open tabs
  These change frequently as the user switches files/tabs. Injected as a
  synthetic <environment_details> block on each user message so the model
  always has fresh context.

This matches the pattern used by the VS Code extension, where
getEnvironmentDetails() is called before every agent turn.
---
 .../opencode/src/kilocode/editor-context.ts   | 42 ++++++++++++-------
 packages/opencode/src/session/prompt.ts       | 15 +++++++
 packages/opencode/src/session/system.ts       |  4 +-
 3 files changed, 45 insertions(+), 16 deletions(-)

diff --git a/packages/opencode/src/kilocode/editor-context.ts b/packages/opencode/src/kilocode/editor-context.ts
index 06085e9301f..f5da9bfa33d 100644
--- a/packages/opencode/src/kilocode/editor-context.ts
+++ b/packages/opencode/src/kilocode/editor-context.ts
@@ -6,36 +6,50 @@ export interface EditorContext {
   timezone?: string
 }
 
-function formatDate(timezone?: string): string[] {
+/**
+ * Build static <env> lines from editor context.
+ * These rarely change during a session and belong in the system prompt
+ * so they benefit from prompt caching.
+ */
+export function staticEnvLines(ctx?: EditorContext): string[] {
   const now = new Date()
   const lines = [`  Today's date: ${now.toDateString()}`]
-  if (timezone) {
+  if (ctx?.timezone) {
     const offset = -now.getTimezoneOffset()
     const sign = offset >= 0 ? "+" : "-"
     const hours = Math.floor(Math.abs(offset) / 60)
     const mins = Math.abs(offset) % 60
-    lines.push(`  User timezone: ${timezone}, UTC${sign}${hours}:${mins.toString().padStart(2, "0")}`)
+    lines.push(`  User timezone: ${ctx.timezone}, UTC${sign}${hours}:${mins.toString().padStart(2, "0")}`)
+  }
+  if (ctx?.shell) {
+    lines.push(`  Default shell: ${ctx.shell}`)
   }
   return lines
 }
 
 /**
- * Build additional <env> lines from VS Code editor context.
- * Returns an array of pre-formatted `  key: value` strings.
+ * Build a per-message <environment_details> block from editor context.
+ * These change frequently (user switches files/tabs) and belong in the
+ * user message so the model always has fresh context.
+ * Returns undefined when there is nothing dynamic to report.
  */
-export function editorContextEnvLines(ctx?: EditorContext): string[] {
-  const lines = formatDate(ctx?.timezone)
-  if (ctx?.shell) {
-    lines.push(`  Default shell: ${ctx.shell}`)
-  }
+export function environmentDetails(ctx?: EditorContext): string | undefined {
+  const lines: string[] = []
   if (ctx?.activeFile) {
-    lines.push(`  Active file: ${ctx.activeFile}`)
+    lines.push(`Active file: ${ctx.activeFile}`)
   }
   if (ctx?.visibleFiles?.length) {
-    lines.push(`  Visible files: ${ctx.visibleFiles.join(", ")}`)
+    lines.push(`Visible files:`)
+    for (const f of ctx.visibleFiles) {
+      lines.push(`  ${f}`)
+    }
   }
   if (ctx?.openTabs?.length) {
-    lines.push(`  Open tabs: ${ctx.openTabs.join(", ")}`)
+    lines.push(`Open tabs:`)
+    for (const f of ctx.openTabs) {
+      lines.push(`  ${f}`)
+    }
   }
-  return lines
+  if (lines.length === 0) return undefined
+  return ["<environment_details>", ...lines, "</environment_details>"].join("\n")
 }
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index 6779ecc6e12..f90e55ac918 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -47,6 +47,7 @@ import { iife } from "@/util/iife"
 import { Shell } from "@/shell/shell"
 import { Truncate } from "@/tool/truncation"
 import { PlanFollowup } from "@/kilocode/plan-followup" // kilocode_change
+import { environmentDetails } from "@/kilocode/editor-context" // kilocode_change
 
 // @ts-ignore
 globalThis.AI_SDK_LOG_WARNINGS = false
@@ -1355,6 +1356,20 @@ export namespace SessionPrompt {
       }),
     ).then((x) => x.flat().map(assign))
 
+    // kilocode_change start — inject dynamic editor context into user message
+    const envBlock = environmentDetails(input.editorContext)
+    if (envBlock) {
+      parts.push({
+        id: Identifier.ascending("part"),
+        messageID: info.id,
+        sessionID: input.sessionID,
+        type: "text",
+        text: envBlock,
+        synthetic: true,
+      })
+    }
+    // kilocode_change end
+
     await Plugin.trigger(
       "chat.message",
       {
diff --git a/packages/opencode/src/session/system.ts b/packages/opencode/src/session/system.ts
index 4c793c014b8..348fd881062 100644
--- a/packages/opencode/src/session/system.ts
+++ b/packages/opencode/src/session/system.ts
@@ -13,7 +13,7 @@ import type { Provider } from "@/provider/provider"
 
 // kilocode_change start
 import SOUL from "../kilocode/soul.txt"
-import { editorContextEnvLines, type EditorContext } from "../kilocode/editor-context"
+import { staticEnvLines, type EditorContext } from "../kilocode/editor-context"
 // kilocode_change end
 
 export namespace SystemPrompt {
@@ -67,7 +67,7 @@ export namespace SystemPrompt {
         `  Working directory: ${Instance.directory}`,
         `  Is directory a git repo: ${project.vcs === "git" ? "yes" : "no"}`,
         `  Platform: ${process.platform}`,
-        ...editorContextEnvLines(editorContext), // kilocode_change
+        ...staticEnvLines(editorContext), // kilocode_change
         `</env>`,
         `<directories>`,
         `  ${