diff --git a/AGENTS.md b/AGENTS.md
index d711b4214d..308348c6ae 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -177,7 +177,24 @@ def _register_builtins() -> None:
 
 Set `context_file` on the integration class. The base integration setup creates or updates the managed Spec Kit section in that file, and uninstall removes the managed section when appropriate.
 
-Only add custom setup logic when the agent needs non-standard behavior. Most integrations do not need wrapper scripts or separate context-update dispatch code.
+The managed section is owned by the bundled `agent-context` extension (`extensions/agent-context/`). All configuration flows through the extension's own config file at `.specify/extensions/agent-context/agent-context-config.yml`:
+
+```yaml
+# Path to the coding agent context file managed by this extension
+context_file: CLAUDE.md
+
+# Delimiters for the managed Spec Kit section
+context_markers:
+  start: "<!-- SPECKIT START -->"
+  end: "<!-- SPECKIT END -->"
+```
+
+- `context_file` is written automatically from the integration's class attribute when `specify init` or `specify integration use` is run.
+- `context_markers.{start,end}` defaults to `IntegrationBase.CONTEXT_MARKER_START` / `CONTEXT_MARKER_END`. Users who want custom markers edit `agent-context-config.yml` directly — both the Python layer (`upsert_context_section()` / `remove_context_section()`) and the bundled scripts (`extensions/agent-context/scripts/bash/update-agent-context.sh` and `.ps1`) read from this single source of truth.
+
+Users can opt out entirely with `specify extension disable agent-context`; while disabled, Spec Kit skips context-file creation, updates, and removal (the gates are inside `upsert_context_section()` and `remove_context_section()`).
+
+Only add custom setup logic when the agent needs non-standard behavior. Integrations no longer require per-agent thin wrapper scripts or shared context-update dispatcher scripts — the `agent-context` extension is fully generic.
 
 ### 5. Test it
 
@@ -382,7 +399,7 @@ Implementation: Extends `YamlIntegration` (parallel to `TomlIntegration`):
 ## Common Pitfalls
 
 1. **Using shorthand keys for CLI-based integrations**: For CLI-based integrations (`requires_cli: True`), the `key` must match the executable name (e.g., `"cursor-agent"` not `"cursor"`). `shutil.which(key)` is used for CLI tool checks — mismatches require special-case mappings. IDE-based integrations (`requires_cli: False`) are not subject to this constraint.
-2. **Forgetting update scripts**: Both bash and PowerShell thin wrappers and the shared context-update scripts must be updated.
+2. **Forgetting context configuration**: The bundled `agent-context` extension reads from `.specify/extensions/agent-context/agent-context-config.yml`. New integrations only need to set `context_file` on the class — markers and dispatcher scripts are managed centrally.
 3. **Incorrect `requires_cli` value**: Set to `True` only for agents that have a CLI tool; set to `False` for IDE-based agents.
 4. **Wrong argument format**: Use `$ARGUMENTS` for Markdown agents, `{{args}}` for TOML agents.
 5. **Skipping registration**: The import and `_register()` call in `_register_builtins()` must both be added.
diff --git a/extensions/agent-context/README.md b/extensions/agent-context/README.md
new file mode 100644
index 0000000000..dba004eb80
--- /dev/null
+++ b/extensions/agent-context/README.md
@@ -0,0 +1,57 @@
+# Coding Agent Context Extension
+
+This bundled extension manages the **coding agent context/instruction file** (e.g. `CLAUDE.md`, `.github/copilot-instructions.md`, `AGENTS.md`, `GEMINI.md`, …) for the active integration.
+
+It owns the lifecycle of the managed section delimited by the configurable start/end markers (defaults: `<!-- SPECKIT START -->` / `<!-- SPECKIT END -->`).
+
+## Why an extension?
+
+Not every Spec Kit user wants Spec Kit to write into the coding agent's context file. Extracting this behavior into a dedicated extension lets users:
+
+- **Opt out** entirely with `specify extension disable agent-context` — Spec Kit will then never create or modify the agent context file.
+- **Customize the markers** by editing `.specify/extensions/agent-context/agent-context-config.yml` — both the Python layer and the bundled scripts honor the same `context_markers` value.
+- **Refresh on demand** with `/speckit.agent-context.update`, or automatically through the hooks declared in `extension.yml` (`after_specify`, `after_plan`).
+
+## Commands
+
+| Command | Description |
+|---------|-------------|
+| `speckit.agent-context.update` | Refresh the managed section in the agent context file with the current plan path. |
+
+## Configuration
+
+All configuration flows through the extension's own config file at
+`.specify/extensions/agent-context/agent-context-config.yml`:
+
+```yaml
+# Path to the coding agent context file managed by this extension
+context_file: CLAUDE.md
+
+# Delimiters for the managed Spec Kit section
+context_markers:
+  start: "<!-- SPECKIT START -->"
+  end: "<!-- SPECKIT END -->"
+```
+
+- `context_file` — the project-relative path to the coding agent context file, written by `specify init` and `specify integration install`.
+- `context_markers.start` / `.end` — the delimiters around the managed section. Edit these to use custom markers.
+
+## Requirements
+
+The bundled update scripts require **Python 3** with **PyYAML** for YAML/upsert processing (PowerShell can also use `ConvertFrom-Yaml` when available).
+
+PyYAML ships with the `specify` CLI and is normally available via the same `python3` interpreter. If a hook reports *"PyYAML is required … not available in the current Python environment"*, it means the system `python3` differs from the one used to install Spec Kit. To resolve, run:
+
+```bash
+pip install pyyaml
+# or target the specific interpreter Spec Kit uses:
+/path/to/speckit-python -m pip install pyyaml
+```
+
+## Disable
+
+```bash
+specify extension disable agent-context
+```
+
+When disabled, Spec Kit skips context file creation, updates, and removal (the gates are inside `upsert_context_section()` and `remove_context_section()`).
diff --git a/extensions/agent-context/agent-context-config.yml b/extensions/agent-context/agent-context-config.yml
new file mode 100644
index 0000000000..8c8d308b27
--- /dev/null
+++ b/extensions/agent-context/agent-context-config.yml
@@ -0,0 +1,15 @@
+# Coding Agent Context Extension Configuration
+# These values are populated automatically by `specify init` and
+# `specify integration use` / `specify integration install`.
+
+# Path (relative to the project root) to the coding agent context file
+# managed by this extension (e.g. CLAUDE.md, AGENTS.md,
+# .github/copilot-instructions.md). Set automatically from the active
+# integration and regenerated during `specify init` or integration switches.
+context_file: ""
+
+# Delimiters for the managed Spec Kit section.
+# Edit these to use custom markers.
+context_markers:
+  start: "<!-- SPECKIT START -->"
+  end: "<!-- SPECKIT END -->"
diff --git a/extensions/agent-context/commands/speckit.agent-context.update.md b/extensions/agent-context/commands/speckit.agent-context.update.md
new file mode 100644
index 0000000000..02f1706926
--- /dev/null
+++ b/extensions/agent-context/commands/speckit.agent-context.update.md
@@ -0,0 +1,26 @@
+---
+description: "Refresh the managed Spec Kit section in the coding agent context file"
+---
+
+# Update Coding Agent Context
+
+Refresh the managed Spec Kit section inside the active coding agent's context/instruction file (e.g. `CLAUDE.md`, `.github/copilot-instructions.md`, `AGENTS.md`).
+
+## Behavior
+
+The script reads the agent-context extension config at
+`.specify/extensions/agent-context/agent-context-config.yml` to discover:
+
+- `context_file` — the path of the coding agent context file to manage.
+- `context_markers.start` / `.end` — the delimiters surrounding the managed section. Defaults to `<!-- SPECKIT START -->` and `<!-- SPECKIT END -->` when the field is missing.
+
+It then creates, replaces, or appends the managed block so that the section points at the most recent plan path when one can be discovered (`specs/<feature>/plan.md`).
+
+If `context_file` is empty or the file cannot be located, the command reports nothing to do and exits successfully.
+
+## Execution
+
+- **Bash**: `.specify/extensions/agent-context/scripts/bash/update-agent-context.sh [plan_path]`
+- **PowerShell**: `.specify/extensions/agent-context/scripts/powershell/update-agent-context.ps1 [plan_path]`
+
+When `plan_path` is omitted, the script auto-detects the most recently modified `specs/*/plan.md`.
diff --git a/extensions/agent-context/extension.yml b/extensions/agent-context/extension.yml
new file mode 100644
index 0000000000..191069e32c
--- /dev/null
+++ b/extensions/agent-context/extension.yml
@@ -0,0 +1,34 @@
+schema_version: "1.0"
+
+extension:
+  id: agent-context
+  name: "Coding Agent Context"
+  version: "1.0.0"
+  description: "Manages coding agent context/instruction files (e.g., CLAUDE.md, copilot-instructions.md) with project-specific plan references and configurable markers"
+  author: spec-kit-core
+  repository: https://github.com/github/spec-kit
+  license: MIT
+
+requires:
+  speckit_version: ">=0.2.0"
+
+provides:
+  commands:
+    - name: speckit.agent-context.update
+      file: commands/speckit.agent-context.update.md
+      description: "Refresh the managed Spec Kit section in the coding agent context file"
+
+hooks:
+  after_specify:
+    command: speckit.agent-context.update
+    optional: true
+    description: "Refresh agent context after specification"
+  after_plan:
+    command: speckit.agent-context.update
+    optional: true
+    description: "Refresh agent context after planning"
+
+tags:
+  - "agent"
+  - "context"
+  - "core"
diff --git a/extensions/agent-context/scripts/bash/update-agent-context.sh b/extensions/agent-context/scripts/bash/update-agent-context.sh
new file mode 100755
index 0000000000..62cc0a7281
--- /dev/null
+++ b/extensions/agent-context/scripts/bash/update-agent-context.sh
@@ -0,0 +1,182 @@
+#!/usr/bin/env bash
+# update-agent-context.sh
+#
+# Refresh the managed Spec Kit section in the coding agent's context file
+# (e.g. CLAUDE.md, .github/copilot-instructions.md, AGENTS.md).
+#
+# Reads `context_file` and `context_markers.{start,end}` from the
+# agent-context extension config:
+#   .specify/extensions/agent-context/agent-context-config.yml
+#
+# Usage: update-agent-context.sh [plan_path]
+#
+# When `plan_path` is omitted, the script picks the most recently modified
+# `specs/*/plan.md` if any exist, otherwise emits the section without a
+# concrete plan path.
+
+set -euo pipefail
+
+PROJECT_ROOT="$(pwd)"
+EXT_CONFIG="$PROJECT_ROOT/.specify/extensions/agent-context/agent-context-config.yml"
+DEFAULT_START="<!-- SPECKIT START -->"
+DEFAULT_END="<!-- SPECKIT END -->"
+
+if [[ ! -f "$EXT_CONFIG" ]]; then
+  echo "agent-context: $EXT_CONFIG not found; nothing to do." >&2
+  exit 0
+fi
+
+# Locate a suitable Python interpreter (python3, then python).
+_python=""
+if command -v python3 >/dev/null 2>&1; then
+  _python="python3"
+elif command -v python >/dev/null 2>&1 && python --version 2>&1 | grep -q "^Python 3"; then
+  _python="python"
+fi
+
+if [[ -z "$_python" ]]; then
+  echo "agent-context: Python 3 not found on PATH; skipping update." >&2
+  exit 0
+fi
+
+# Parse extension config once; emit three newline-separated fields:
+# context_file, context_markers.start, context_markers.end
+if ! _raw_opts="$("$_python" - "$EXT_CONFIG" <<'PY'
+import sys
+try:
+    import yaml
+except ImportError:
+    print(
+        "agent-context: PyYAML is required to parse extension config but is not available "
+        "in the current Python environment.\n"
+        "  To resolve: pip install pyyaml (or install it into the environment used by python3).\n"
+        "  Context file will not be updated until PyYAML is importable.",
+        file=sys.stderr,
+    )
+    sys.exit(2)
+try:
+    with open(sys.argv[1], "r", encoding="utf-8") as fh:
+        data = yaml.safe_load(fh)
+except Exception as exc:
+    print(
+        f"agent-context: unable to parse {sys.argv[1]} ({exc}); cannot update context.",
+        file=sys.stderr,
+    )
+    sys.exit(2)
+if not isinstance(data, dict):
+    data = {}
+def get_str(obj, *keys):
+    node = obj
+    for k in keys:
+        if isinstance(node, dict) and k in node:
+            node = node[k]
+        else:
+            return ""
+    return node if isinstance(node, str) else ""
+print(get_str(data, "context_file"))
+print(get_str(data, "context_markers", "start"))
+print(get_str(data, "context_markers", "end"))
+PY
+)"; then
+  echo "agent-context: skipping update (see above for details)." >&2
+  exit 0
+fi
+
+_opts_lines=()
+while IFS= read -r _line || [[ -n "$_line" ]]; do
+  _opts_lines+=("$_line")
+done < <(printf '%s\n' "$_raw_opts")
+if (( ${#_opts_lines[@]} < 3 )); then
+  echo "agent-context: malformed config parser output; expected 3 lines (context_file, marker_start, marker_end), got ${#_opts_lines[@]}; skipping update." >&2
+  exit 0
+fi
+CONTEXT_FILE="${_opts_lines[0]}"
+MARKER_START="${_opts_lines[1]}"
+MARKER_END="${_opts_lines[2]}"
+
+if [[ -z "$CONTEXT_FILE" ]]; then
+  echo "agent-context: context_file not set in extension config; nothing to do." >&2
+  exit 0
+fi
+
+[[ -z "$MARKER_START" ]] && MARKER_START="$DEFAULT_START"
+[[ -z "$MARKER_END"   ]] && MARKER_END="$DEFAULT_END"
+
+PLAN_PATH="${1:-}"
+if [[ -z "$PLAN_PATH" ]]; then
+  # Pick the most recently modified plan.md one level deep (specs/<feature>/plan.md).
+  # Use find + sort by modification time to avoid ls/head fragility with
+  # spaces in paths or SIGPIPE from pipefail.
+  _plan_abs="$("$_python" - "$PROJECT_ROOT" <<'PY'
+import sys, os
+from pathlib import Path
+specs = Path(sys.argv[1]) / "specs"
+plans = sorted(
+    specs.glob("*/plan.md"),
+    key=lambda p: p.stat().st_mtime,
+    reverse=True,
+)
+print(plans[0] if plans else "")
+PY
+)"
+  if [[ -n "$_plan_abs" ]]; then
+    PLAN_PATH="${_plan_abs#"$PROJECT_ROOT/"}"
+  fi
+fi
+
+CTX_PATH="$PROJECT_ROOT/$CONTEXT_FILE"
+mkdir -p "$(dirname "$CTX_PATH")"
+
+# Build the managed section
+TMP_SECTION="$(mktemp)"
+trap 'rm -f "$TMP_SECTION"' EXIT
+{
+  echo "$MARKER_START"
+  echo "For additional context about technologies to be used, project structure,"
+  echo "shell commands, and other important information, read the current plan"
+  if [[ -n "$PLAN_PATH" ]]; then
+    echo "at $PLAN_PATH"
+  fi
+  echo "$MARKER_END"
+} > "$TMP_SECTION"
+
+"$_python" - "$CTX_PATH" "$MARKER_START" "$MARKER_END" "$TMP_SECTION" <<'PY'
+import sys, os
+ctx_path, start, end, section_path = sys.argv[1:5]
+with open(section_path, "r", encoding="utf-8") as fh:
+    section = fh.read().rstrip("\n") + "\n"
+
+if os.path.exists(ctx_path):
+    with open(ctx_path, "r", encoding="utf-8-sig") as fh:
+        content = fh.read()
+    s = content.find(start)
+    e = content.find(end, s if s != -1 else 0)
+    if s != -1 and e != -1 and e > s:
+        end_of_marker = e + len(end)
+        if end_of_marker < len(content) and content[end_of_marker] == "\r":
+            end_of_marker += 1
+        if end_of_marker < len(content) and content[end_of_marker] == "\n":
+            end_of_marker += 1
+        new_content = content[:s] + section + content[end_of_marker:]
+    elif s != -1:
+        new_content = content[:s] + section
+    elif e != -1:
+        end_of_marker = e + len(end)
+        if end_of_marker < len(content) and content[end_of_marker] == "\r":
+            end_of_marker += 1
+        if end_of_marker < len(content) and content[end_of_marker] == "\n":
+            end_of_marker += 1
+        new_content = section + content[end_of_marker:]
+    else:
+        if content and not content.endswith("\n"):
+            content += "\n"
+        new_content = (content + "\n" + section) if content else section
+else:
+    new_content = section
+
+new_content = new_content.replace("\r\n", "\n").replace("\r", "\n")
+with open(ctx_path, "wb") as fh:
+    fh.write(new_content.encode("utf-8"))
+PY
+
+echo "agent-context: updated $CONTEXT_FILE"
diff --git a/extensions/agent-context/scripts/powershell/update-agent-context.ps1 b/extensions/agent-context/scripts/powershell/update-agent-context.ps1
new file mode 100644
index 0000000000..db8180a5da
--- /dev/null
+++ b/extensions/agent-context/scripts/powershell/update-agent-context.ps1
@@ -0,0 +1,222 @@
+#!/usr/bin/env pwsh
+# update-agent-context.ps1
+#
+# Refresh the managed Spec Kit section in the coding agent's context file
+# (e.g. CLAUDE.md, .github/copilot-instructions.md, AGENTS.md).
+#
+# Reads `context_file` and `context_markers.{start,end}` from the
+# agent-context extension config:
+#   .specify/extensions/agent-context/agent-context-config.yml
+#
+# Usage: update-agent-context.ps1 [plan_path]
+
+[CmdletBinding()]
+param(
+    [Parameter(Position = 0)]
+    [string]$PlanPath
+)
+
+function Get-ConfigValue {
+    param(
+        [AllowNull()][object]$Object,
+        [Parameter(Mandatory = $true)][string]$Key
+    )
+
+    if ($null -eq $Object) {
+        return $null
+    }
+    if ($Object -is [System.Collections.IDictionary]) {
+        return $Object[$Key]
+    }
+    $prop = $Object.PSObject.Properties[$Key]
+    if ($prop) {
+        return $prop.Value
+    }
+    return $null
+}
+
+function Test-ConfigObject {
+    param(
+        [AllowNull()][object]$Object
+    )
+
+    if ($null -eq $Object) {
+        return $false
+    }
+    if ($Object -is [System.Collections.IDictionary]) {
+        return $true
+    }
+    if ($Object -is [System.Management.Automation.PSCustomObject]) {
+        return $true
+    }
+    return $false
+}
+
+$ErrorActionPreference = 'Stop'
+$DefaultStart = '<!-- SPECKIT START -->'
+$DefaultEnd   = '<!-- SPECKIT END -->'
+$ProjectRoot  = (Get-Location).Path
+$ExtConfig    = Join-Path $ProjectRoot '.specify/extensions/agent-context/agent-context-config.yml'
+
+if (-not (Test-Path -LiteralPath $ExtConfig)) {
+    Write-Warning "agent-context: $ExtConfig not found; nothing to do."
+    exit 0
+}
+
+$Options = $null
+if (Get-Command ConvertFrom-Yaml -ErrorAction SilentlyContinue) {
+    try {
+        $Options = Get-Content -LiteralPath $ExtConfig -Raw | ConvertFrom-Yaml -ErrorAction Stop
+    } catch {
+        # fall through to Python fallback
+    }
+}
+
+if ($null -eq $Options) {
+    # ConvertFrom-Yaml unavailable or failed; fall back to Python+PyYAML.
+    $pythonCmd = $null
+    foreach ($candidate in @('python3', 'python')) {
+        if (Get-Command $candidate -ErrorAction SilentlyContinue) {
+            $pythonCmd = $candidate
+            break
+        }
+    }
+
+    if ($pythonCmd) {
+        try {
+            $jsonOut = & $pythonCmd -c @'
+import json
+import sys
+try:
+    import yaml
+except ImportError:
+    print(
+        "agent-context: PyYAML is required to parse extension config; cannot update context.",
+        file=sys.stderr,
+    )
+    sys.exit(2)
+
+try:
+    with open(sys.argv[1], "r", encoding="utf-8") as fh:
+        data = yaml.safe_load(fh)
+except Exception as exc:
+    print(
+        f"agent-context: unable to parse {sys.argv[1]} ({exc}); cannot update context.",
+        file=sys.stderr,
+    )
+    sys.exit(2)
+
+if not isinstance(data, dict):
+    data = {}
+
+print(json.dumps(data))
+'@ $ExtConfig
+            if ($LASTEXITCODE -eq 0 -and $jsonOut) {
+                $Options = $jsonOut | ConvertFrom-Json -ErrorAction Stop
+            }
+        } catch {
+            $Options = $null
+        }
+    }
+
+    if (-not $Options) {
+        Write-Warning "agent-context: unable to parse $ExtConfig; skipping update."
+        exit 0
+    }
+}
+
+if (-not (Test-ConfigObject -Object $Options)) {
+    Write-Warning "agent-context: $ExtConfig must contain a YAML mapping; skipping update."
+    exit 0
+}
+
+$ContextFile = Get-ConfigValue -Object $Options -Key 'context_file'
+if (-not $ContextFile) {
+    Write-Warning 'agent-context: context_file not set in extension config; nothing to do.'
+    exit 0
+}
+
+$MarkerStart = $DefaultStart
+$MarkerEnd   = $DefaultEnd
+$cm = Get-ConfigValue -Object $Options -Key 'context_markers'
+if ($cm) {
+    $cmStart = Get-ConfigValue -Object $cm -Key 'start'
+    if ($cmStart -is [string] -and $cmStart) {
+        $MarkerStart = $cmStart
+    }
+    $cmEnd = Get-ConfigValue -Object $cm -Key 'end'
+    if ($cmEnd -is [string] -and $cmEnd) {
+        $MarkerEnd = $cmEnd
+    }
+}
+
+if (-not $PlanPath) {
+    # Discover plan.md exactly one level deep (specs/<feature>/plan.md),
+    # matching the bash glob specs/*/plan.md. Wrap in try/catch so access errors under
+    # $ErrorActionPreference = 'Stop' don't abort the script.
+    try {
+        $specsDir = Join-Path $ProjectRoot 'specs'
+        $candidate = Get-ChildItem -Path $specsDir -Directory -ErrorAction SilentlyContinue |
+            ForEach-Object { Get-Item -LiteralPath (Join-Path $_.FullName 'plan.md') -ErrorAction SilentlyContinue } |
+            Where-Object { $_ } |
+            Sort-Object LastWriteTime -Descending |
+            Select-Object -First 1
+        if ($candidate) {
+            $PlanPath = [System.IO.Path]::GetRelativePath($ProjectRoot, $candidate.FullName).Replace('\','/')
+        }
+    } catch {
+        # Non-fatal: continue without a plan path.
+    }
+}
+
+$CtxPath = Join-Path $ProjectRoot $ContextFile
+$CtxDir  = Split-Path -Parent $CtxPath
+if ($CtxDir -and -not (Test-Path -LiteralPath $CtxDir)) {
+    New-Item -ItemType Directory -Path $CtxDir -Force | Out-Null
+}
+
+$lines = @($MarkerStart,
+           'For additional context about technologies to be used, project structure,',
+           'shell commands, and other important information, read the current plan')
+if ($PlanPath) {
+    $lines += "at $PlanPath"
+}
+$lines += $MarkerEnd
+$Section = ($lines -join "`n") + "`n"
+
+if (Test-Path -LiteralPath $CtxPath) {
+    $rawBytes = [System.IO.File]::ReadAllBytes($CtxPath)
+    # Strip UTF-8 BOM if present
+    if ($rawBytes.Length -ge 3 -and $rawBytes[0] -eq 0xEF -and $rawBytes[1] -eq 0xBB -and $rawBytes[2] -eq 0xBF) {
+        $content = [System.Text.Encoding]::UTF8.GetString($rawBytes, 3, $rawBytes.Length - 3)
+    } else {
+        $content = [System.Text.Encoding]::UTF8.GetString($rawBytes)
+    }
+
+    $s = $content.IndexOf($MarkerStart)
+    $e = if ($s -ge 0) { $content.IndexOf($MarkerEnd, $s) } else { $content.IndexOf($MarkerEnd) }
+
+    if ($s -ge 0 -and $e -ge 0 -and $e -gt $s) {
+        $endOfMarker = $e + $MarkerEnd.Length
+        if ($endOfMarker -lt $content.Length -and $content[$endOfMarker] -eq "`r") { $endOfMarker++ }
+        if ($endOfMarker -lt $content.Length -and $content[$endOfMarker] -eq "`n") { $endOfMarker++ }
+        $newContent = $content.Substring(0, $s) + $Section + $content.Substring($endOfMarker)
+    } elseif ($s -ge 0) {
+        $newContent = $content.Substring(0, $s) + $Section
+    } elseif ($e -ge 0) {
+        $endOfMarker = $e + $MarkerEnd.Length
+        if ($endOfMarker -lt $content.Length -and $content[$endOfMarker] -eq "`r") { $endOfMarker++ }
+        if ($endOfMarker -lt $content.Length -and $content[$endOfMarker] -eq "`n") { $endOfMarker++ }
+        $newContent = $Section + $content.Substring($endOfMarker)
+    } else {
+        if ($content -and -not $content.EndsWith("`n")) { $content += "`n" }
+        if ($content) { $newContent = $content + "`n" + $Section } else { $newContent = $Section }
+    }
+} else {
+    $newContent = $Section
+}
+
+$newContent = $newContent.Replace("`r`n", "`n").Replace("`r", "`n")
+[System.IO.File]::WriteAllText($CtxPath, $newContent, (New-Object System.Text.UTF8Encoding($false)))
+
+Write-Host "agent-context: updated $ContextFile"
diff --git a/extensions/catalog.json b/extensions/catalog.json
index de9372e2bc..284e9abe75 100644
--- a/extensions/catalog.json
+++ b/extensions/catalog.json
@@ -3,6 +3,20 @@
   "updated_at": "2026-04-10T00:00:00Z",
   "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/extensions/catalog.json",
   "extensions": {
+    "agent-context": {
+      "name": "Coding Agent Context",
+      "id": "agent-context",
+      "version": "1.0.0",
+      "description": "Manages coding agent context/instruction files (e.g., CLAUDE.md, copilot-instructions.md) with project-specific plan references and configurable markers",
+      "author": "spec-kit-core",
+      "repository": "https://github.com/github/spec-kit",
+      "bundled": true,
+      "tags": [
+        "agent",
+        "context",
+        "core"
+      ]
+    },
     "git": {
       "name": "Git Branching Workflow",
       "id": "git",
diff --git a/src/specify_cli/__init__.py b/src/specify_cli/__init__.py
index d4e8632215..25092a508a 100644
--- a/src/specify_cli/__init__.py
+++ b/src/specify_cli/__init__.py
@@ -412,6 +412,72 @@ def load_init_options(project_path: Path) -> dict[str, Any]:
         return {}
 
 
+# ---------------------------------------------------------------------------
+# Agent-context extension config helpers
+# ---------------------------------------------------------------------------
+
+_AGENT_CTX_EXT_CONFIG = (
+    Path(".specify") / "extensions" / "agent-context" / "agent-context-config.yml"
+)
+
+
+def _load_agent_context_config(project_root: Path) -> dict[str, Any]:
+    """Load the agent-context extension config, returning defaults on failure."""
+    from .integrations.base import IntegrationBase
+
+    defaults: dict[str, Any] = {
+        "context_file": "",
+        "context_markers": {
+            "start": IntegrationBase.CONTEXT_MARKER_START,
+            "end": IntegrationBase.CONTEXT_MARKER_END,
+        },
+    }
+    path = project_root / _AGENT_CTX_EXT_CONFIG
+    if not path.exists():
+        return defaults
+    try:
+        raw = yaml.safe_load(path.read_text(encoding="utf-8"))
+    except (OSError, yaml.YAMLError):
+        return defaults
+    if not isinstance(raw, dict):
+        return defaults
+    return raw
+
+
+def _save_agent_context_config(
+    project_root: Path, config: dict[str, Any]
+) -> None:
+    """Persist *config* to the agent-context extension config file."""
+    path = project_root / _AGENT_CTX_EXT_CONFIG
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(yaml.safe_dump(config, default_flow_style=False), encoding="utf-8")
+
+
+def _update_agent_context_config_file(
+    project_root: Path,
+    context_file: str | None,
+    *,
+    preserve_markers: bool = True,
+) -> None:
+    """Update the agent-context extension config with *context_file*.
+
+    When *preserve_markers* is True (default), any existing
+    ``context_markers`` values are kept unchanged so user customisations
+    survive integration changes and reinit.  When False, the default
+    markers are written unconditionally.
+    """
+    from .integrations.base import IntegrationBase
+
+    cfg = _load_agent_context_config(project_root)
+    cfg["context_file"] = context_file or ""
+    if not preserve_markers or not isinstance(cfg.get("context_markers"), dict):
+        cfg["context_markers"] = {
+            "start": IntegrationBase.CONTEXT_MARKER_START,
+            "end": IntegrationBase.CONTEXT_MARKER_END,
+        }
+    _save_agent_context_config(project_root, cfg)
+
+
 def _get_skills_dir(project_path: Path, selected_ai: str) -> Path:
     """Resolve the agent-specific skills directory.
 
@@ -747,6 +813,7 @@ def init(
         ("chmod", "Ensure scripts executable"),
         ("constitution", "Constitution setup"),
         ("git", "Install git extension"),
+        ("agent-context", "Install agent-context extension"),
         ("workflow", "Install bundled workflow"),
         ("final", "Finalize"),
     ]:
@@ -900,30 +967,105 @@ def init(
                 sanitized_wf = str(wf_err).replace('\n', ' ').strip()
                 tracker.error("workflow", f"install failed: {sanitized_wf[:120]}")
 
-            # Fix permissions after all installs (scripts + extensions)
-            ensure_executable_scripts(project_path, tracker=tracker)
-
             # Persist the CLI options so later operations (e.g. preset add)
             # can adapt their behaviour without re-scanning the filesystem.
             # Must be saved BEFORE preset install so _get_skills_dir() works.
+            # Also saved BEFORE agent-context install so init-options.json is
+            # available when the extension's hooks run.
+            from .integrations.base import SkillsIntegration as _SkillsPersist
             init_opts = {
                 "ai": selected_ai,
                 "integration": resolved_integration.key,
                 "branch_numbering": branch_numbering or "sequential",
-                "context_file": resolved_integration.context_file,
                 "here": here,
                 "script": selected_script,
                 "speckit_version": get_speckit_version(),
             }
-            # Ensure ai_skills is set for SkillsIntegration so downstream
-            # tools (extensions, presets) emit SKILL.md overrides correctly.
-            # Also set for integrations running in skills mode (e.g. Copilot
-            # with --skills).
-            from .integrations.base import SkillsIntegration as _SkillsPersist
+            # context_file and context_markers live in the agent-context
+            # extension config, not in init-options.json.
             if isinstance(resolved_integration, _SkillsPersist) or getattr(resolved_integration, "_skills_mode", False):
                 init_opts["ai_skills"] = True
             save_init_options(project_path, init_opts)
 
+            # Install bundled agent-context extension (opt-out via
+            # `specify extension disable agent-context`). Owns the managed
+            # section in coding agent context files (CLAUDE.md, etc.).
+            # Installed after init-options are saved so project metadata
+            # reflects the selected integration before extension setup.
+            # The extension config is then updated (in finally) with the
+            # active integration's context_file.
+            tracker.start("agent-context")
+            _ac_bundled: Path | None = None
+            _ac_err_msg: str | None = None
+            _ac_terminal: str | None = None
+            _ac_terminal_detail = ""
+            try:
+                from .extensions import ExtensionManager as _AgentCtxMgr
+                _ac_bundled = _locate_bundled_extension("agent-context")
+                if _ac_bundled:
+                    ac_manager = _AgentCtxMgr(project_path)
+                    if ac_manager.registry.is_installed("agent-context"):
+                        _ac_terminal = "complete"
+                        _ac_terminal_detail = "already installed"
+                        tracker.complete("agent-context", _ac_terminal_detail)
+                    else:
+                        ac_manager.install_from_directory(
+                            _ac_bundled, get_speckit_version()
+                        )
+                        _ac_terminal = "complete"
+                        _ac_terminal_detail = "installed"
+                        tracker.complete("agent-context", _ac_terminal_detail)
+                else:
+                    _ac_terminal = "skip"
+                    _ac_terminal_detail = "bundled extension not found"
+                    tracker.skip("agent-context", _ac_terminal_detail)
+            except Exception as ac_err:
+                sanitized_ac = str(ac_err).replace('\n', ' ').strip()
+                _ac_err_msg = f"install failed: {sanitized_ac[:120]}"
+            finally:
+                # Always write context_file into the extension config so the
+                # shell scripts work even if the extension install itself
+                # failed (e.g. dev pre-release version mismatch in CI).
+                # User-customised markers are preserved.
+                if _ac_bundled is not None:
+                    try:
+                        _update_agent_context_config_file(
+                            project_path,
+                            resolved_integration.context_file,
+                            preserve_markers=True,
+                        )
+                        if _ac_err_msg is not None:
+                            # Config was written despite the failed install;
+                            # the Python context-section plumbing remains active.
+                            _ac_err_msg += "; config written, Python context plumbing active"
+                    except Exception as cfg_err:
+                        sanitized_cfg = str(cfg_err).replace('\n', ' ').strip()
+                        cfg_msg = f"config update failed: {sanitized_cfg[:120]}"
+                        if _ac_err_msg is not None:
+                            _ac_err_msg += f"; {cfg_msg}"
+                        else:
+                            _ac_err_msg = cfg_msg
+                if _ac_err_msg is not None:
+                    if _ac_terminal == "complete":
+                        tracker.complete(
+                            "agent-context",
+                            f"{_ac_terminal_detail}; {_ac_err_msg}"
+                            if _ac_terminal_detail
+                            else _ac_err_msg,
+                        )
+                    elif _ac_terminal == "skip":
+                        tracker.skip(
+                            "agent-context",
+                            f"{_ac_terminal_detail}; {_ac_err_msg}"
+                            if _ac_terminal_detail
+                            else _ac_err_msg,
+                        )
+                    else:
+                        tracker.error("agent-context", _ac_err_msg)
+
+            # Fix permissions after all installs (scripts + extensions)
+            ensure_executable_scripts(project_path, tracker=tracker)
+
             # Install preset if specified
             if preset:
                 try:
@@ -1434,13 +1576,31 @@ def _write_integration_json(
 
 
 def _clear_init_options_for_integration(project_root: Path, integration_key: str) -> None:
-    """Clear active integration keys from init-options.json when they match."""
+    """Clear active integration keys from init-options.json when they match.
+
+    Also clears ``context_file`` from the agent-context extension config so
+    no stale path is left behind when the integration is uninstalled.
+    """
     opts = load_init_options(project_root)
+    has_legacy_context_keys = ("context_file" in opts) or ("context_markers" in opts)
+    # Remove legacy fields that older versions may have written.
+    opts.pop("context_file", None)
+    opts.pop("context_markers", None)
+
     if opts.get("integration") == integration_key or opts.get("ai") == integration_key:
         opts.pop("integration", None)
         opts.pop("ai", None)
         opts.pop("ai_skills", None)
-        opts.pop("context_file", None)
+        save_init_options(project_root, opts)
+        # Clear context_file in the extension config if it already exists.
+        # Avoid creating the config (and parent dirs) in projects where the
+        # agent-context extension was never installed.
+        ext_cfg_path = project_root / _AGENT_CTX_EXT_CONFIG
+        if ext_cfg_path.exists():
+            _update_agent_context_config_file(
+                project_root, "", preserve_markers=True
+            )
+    elif has_legacy_context_keys:
         save_init_options(project_root, opts)
 
 
@@ -1858,12 +2018,22 @@ def _update_init_options_for_integration(
     integration: Any,
     script_type: str | None = None,
 ) -> None:
-    """Update ``init-options.json`` to reflect *integration* as the active one."""
+    """Update init-options.json and the agent-context extension config to
+    reflect *integration* as the active one.
+
+    ``context_file`` and ``context_markers`` are stored in the agent-context
+    extension config (``.specify/extensions/agent-context/agent-context-config.yml``),
+    not in ``init-options.json``.  Existing user-customised markers are
+    preserved; the start/end values are only seeded from defaults when they
+    are absent or invalid.
+    """
     from .integrations.base import SkillsIntegration
     opts = load_init_options(project_root)
     opts["integration"] = integration.key
     opts["ai"] = integration.key
-    opts["context_file"] = integration.context_file
+    # Remove legacy fields if they were written by an older version.
+    opts.pop("context_file", None)
+    opts.pop("context_markers", None)
     if script_type:
         opts["script"] = script_type
     if isinstance(integration, SkillsIntegration) or getattr(integration, "_skills_mode", False):
@@ -1872,6 +2042,24 @@ def _update_init_options_for_integration(
         opts.pop("ai_skills", None)
     save_init_options(project_root, opts)
 
+    # Update the agent-context extension config with the new context_file,
+    # preserving any user-customised markers.
+    ext_cfg_path = project_root / _AGENT_CTX_EXT_CONFIG
+    if ext_cfg_path.exists():
+        _update_agent_context_config_file(
+            project_root,
+            integration.context_file,
+            preserve_markers=True,
+        )
+    elif integration.context_file:
+        # Extension config doesn't exist yet (extension not installed).
+        # Write defaults so scripts have something to read.
+        _update_agent_context_config_file(
+            project_root,
+            integration.context_file,
+            preserve_markers=False,
+        )
+
 
 @integration_app.command("use")
 def integration_use(
diff --git a/src/specify_cli/agents.py b/src/specify_cli/agents.py
index a1be34dcc2..9f827640cc 100644
--- a/src/specify_cli/agents.py
+++ b/src/specify_cli/agents.py
@@ -374,8 +374,15 @@ def resolve_skill_placeholders(
 
         body = body.replace("{ARGS}", "$ARGUMENTS").replace("__AGENT__", agent_name)
 
-        # Resolve __CONTEXT_FILE__ from init-options
-        context_file = init_opts.get("context_file") or ""
+        # Resolve __CONTEXT_FILE__ from the agent-context extension config.
+        # Fall back to init-options.json for projects that haven't migrated.
+        # Local import: _load_agent_context_config lives in __init__.py which
+        # imports agents.py, so a top-level import would be circular.
+        from . import _load_agent_context_config
+        ac_cfg = _load_agent_context_config(project_root)
+        context_file = ac_cfg.get("context_file") or ""
+        if not context_file:
+            context_file = init_opts.get("context_file") or ""
         body = body.replace("__CONTEXT_FILE__", context_file)
 
         return CommandRegistrar.rewrite_project_relative_paths(body)
diff --git a/src/specify_cli/integrations/base.py b/src/specify_cli/integrations/base.py
index 7ce107caec..279bd2f65e 100644
--- a/src/specify_cli/integrations/base.py
+++ b/src/specify_cli/integrations/base.py
@@ -13,6 +13,7 @@
 
 from __future__ import annotations
 
+import json
 import re
 import shutil
 from abc import ABC
@@ -482,6 +483,91 @@ def _build_context_section(plan_path: str = "") -> str:
             lines.append(f"at {plan_path}")
         return "\n".join(lines)
 
+    @staticmethod
+    def _agent_context_extension_enabled(project_root: Path) -> bool:
+        """Return whether the bundled ``agent-context`` extension is enabled.
+
+        The extension is the single source of truth for managing coding
+        agent context/instruction files (e.g. ``CLAUDE.md``,
+        ``.github/copilot-instructions.md``).
+
+        Returns ``True`` (enabled) when:
+        - the extension registry does not exist (legacy project, backwards
+          compatibility), or
+        - the registry has no ``agent-context`` entry (older project layout
+          predating the extension), or
+        - the entry is present and not explicitly disabled.
+
+        Returns ``False`` only when an entry exists with ``enabled: false``.
+        """
+        registry_path = (
+            project_root / ".specify" / "extensions" / ".registry"
+        )
+        if not registry_path.exists():
+            return True
+        try:
+            data = json.loads(registry_path.read_text(encoding="utf-8"))
+        except (OSError, ValueError, UnicodeError):
+            return True
+        if not isinstance(data, dict):
+            return True
+        extensions = data.get("extensions")
+        if not isinstance(extensions, dict):
+            return True
+        entry = extensions.get("agent-context")
+        if not isinstance(entry, dict):
+            return True
+        return bool(entry.get("enabled", True))
+
+    def _resolve_context_markers(self, project_root: Path) -> tuple[str, str]:
+        """Return the (start, end) context markers to use for *project_root*.
+
+        Reads ``context_markers.start`` / ``context_markers.end`` from the
+        agent-context extension config
+        (``.specify/extensions/agent-context/agent-context-config.yml``)
+        when present.  Falls back to the class-level constants
+        ``CONTEXT_MARKER_START`` / ``CONTEXT_MARKER_END`` when the file is
+        missing, the section is absent, or the values are not non-empty
+        strings.
+        """
+        from .._console import console  # local import to avoid cycles
+
+        start = self.CONTEXT_MARKER_START
+        end = self.CONTEXT_MARKER_END
+        config_path = (
+            project_root
+            / ".specify"
+            / "extensions"
+            / "agent-context"
+            / "agent-context-config.yml"
+        )
+        try:
+            raw = config_path.read_text(encoding="utf-8")
+            cfg = yaml.safe_load(raw)
+        except (OSError, ValueError, yaml.YAMLError):
+            return start, end
+        markers = cfg.get("context_markers") if isinstance(cfg, dict) else None
+        if isinstance(markers, dict):
+            cm_start = markers.get("start")
+            cm_end = markers.get("end")
+            s_valid = isinstance(cm_start, str) and cm_start
+            e_valid = isinstance(cm_end, str) and cm_end
+            if not s_valid and cm_start is not None:
+                console.print(
+                    f"[yellow]agent-context: ignoring invalid context_markers.start "
+                    f"({cm_start!r}), using default[/yellow]"
+                )
+            if not e_valid and cm_end is not None:
+                console.print(
+                    f"[yellow]agent-context: ignoring invalid context_markers.end "
+                    f"({cm_end!r}), using default[/yellow]"
+                )
+            if s_valid:
+                start = cm_start  # type: ignore[assignment]
+            if e_valid:
+                end = cm_end  # type: ignore[assignment]
+        return start, end
+
     def upsert_context_section(
         self,
         project_root: Path,
@@ -490,9 +576,12 @@ def upsert_context_section(
         """Create or update the managed section in the agent context file.
 
         If the context file does not exist it is created with just the
-        managed section.  If it exists, the content between
-        ``<!-- SPECKIT START -->`` and ``<!-- SPECKIT END -->`` markers
-        is replaced (or appended when no markers are found).
+        managed section.  If it exists, the content between the configured
+        start/end markers (default ``<!-- SPECKIT START -->`` /
+        ``<!-- SPECKIT END -->``) is replaced, or appended when no markers
+        are found. Markers are read from the agent-context extension config
+        (``.specify/extensions/agent-context/agent-context-config.yml``)
+        when present, falling back to the class-level constants.
 
         Returns the path to the context file, or ``None`` when
         ``context_file`` is not set.
@@ -500,24 +589,29 @@ def upsert_context_section(
         if not self.context_file:
             return None
 
+        if not self._agent_context_extension_enabled(project_root):
+            return None
+
+        marker_start, marker_end = self._resolve_context_markers(project_root)
+
         ctx_path = project_root / self.context_file
         section = (
-            f"{self.CONTEXT_MARKER_START}\n"
+            f"{marker_start}\n"
             f"{self._build_context_section(plan_path)}\n"
-            f"{self.CONTEXT_MARKER_END}\n"
+            f"{marker_end}\n"
         )
 
         if ctx_path.exists():
             content = ctx_path.read_text(encoding="utf-8-sig")
-            start_idx = content.find(self.CONTEXT_MARKER_START)
+            start_idx = content.find(marker_start)
             end_idx = content.find(
-                self.CONTEXT_MARKER_END,
+                marker_end,
                 start_idx if start_idx != -1 else 0,
             )
 
             if start_idx != -1 and end_idx != -1 and end_idx > start_idx:
                 # Replace existing section (include the end marker + newline)
-                end_of_marker = end_idx + len(self.CONTEXT_MARKER_END)
+                end_of_marker = end_idx + len(marker_end)
                 # Consume trailing line ending (CRLF or LF)
                 if end_of_marker < len(content) and content[end_of_marker] == "\r":
                     end_of_marker += 1
@@ -529,7 +623,7 @@ def upsert_context_section(
                 new_content = content[:start_idx] + section
             elif end_idx != -1:
                 # Corrupted: end marker without start — replace BOF through end marker
-                end_of_marker = end_idx + len(self.CONTEXT_MARKER_END)
+                end_of_marker = end_idx + len(marker_end)
                 if end_of_marker < len(content) and content[end_of_marker] == "\r":
                     end_of_marker += 1
                 if end_of_marker < len(content) and content[end_of_marker] == "\n":
@@ -563,20 +657,27 @@ def remove_context_section(self, project_root: Path) -> bool:
         """Remove the managed section from the agent context file.
 
         Returns ``True`` if the section was found and removed.  If the
-        file becomes empty (or whitespace-only) after removal it is
-        deleted.
+        file becomes empty (or whitespace-only) after removal it is deleted.
+        Markers are read from the agent-context extension config
+        (``.specify/extensions/agent-context/agent-context-config.yml``)
+        when present, falling back to the class-level constants.
         """
         if not self.context_file:
             return False
 
+        if not self._agent_context_extension_enabled(project_root):
+            return False
+
         ctx_path = project_root / self.context_file
         if not ctx_path.exists():
             return False
 
+        marker_start, marker_end = self._resolve_context_markers(project_root)
+
         content = ctx_path.read_text(encoding="utf-8-sig")
-        start_idx = content.find(self.CONTEXT_MARKER_START)
+        start_idx = content.find(marker_start)
         end_idx = content.find(
-            self.CONTEXT_MARKER_END,
+            marker_end,
             start_idx if start_idx != -1 else 0,
         )
 
@@ -587,7 +688,7 @@ def remove_context_section(self, project_root: Path) -> bool:
             return False
 
         removal_start = start_idx
-        removal_end = end_idx + len(self.CONTEXT_MARKER_END)
+        removal_end = end_idx + len(marker_end)
 
         # Consume trailing line ending (CRLF or LF)
         if removal_end < len(content) and content[removal_end] == "\r":
diff --git a/tests/extensions/test_extension_agent_context.py b/tests/extensions/test_extension_agent_context.py
new file mode 100644
index 0000000000..85981e64da
--- /dev/null
+++ b/tests/extensions/test_extension_agent_context.py
@@ -0,0 +1,377 @@
+"""Tests for the bundled ``agent-context`` extension and related plumbing."""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import yaml
+
+from specify_cli import (
+    _load_agent_context_config,
+    _save_agent_context_config,
+    load_init_options,
+    save_init_options,
+)
+from specify_cli.integrations.base import IntegrationBase
+from specify_cli.integrations.claude import ClaudeIntegration
+
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent.parent
+EXT_DIR = PROJECT_ROOT / "extensions" / "agent-context"
+
+
+def _write_ext_config(project_root: Path, **overrides: object) -> None:
+    """Write a minimal agent-context extension config."""
+    cfg: dict = {
+        "context_file": overrides.get("context_file", ""),
+        "context_markers": overrides.get(
+            "context_markers",
+            {
+                "start": IntegrationBase.CONTEXT_MARKER_START,
+                "end": IntegrationBase.CONTEXT_MARKER_END,
+            },
+        ),
+    }
+    _save_agent_context_config(project_root, cfg)
+
+
+# ── Bundled extension layout ─────────────────────────────────────────────────
+
+
+class TestExtensionLayout:
+    """The bundled agent-context extension ships a complete package."""
+
+    def test_extension_yml_exists(self):
+        assert (EXT_DIR / "extension.yml").is_file()
+
+    def test_extension_yml_has_required_fields(self):
+        manifest = yaml.safe_load((EXT_DIR / "extension.yml").read_text())
+        assert manifest["extension"]["id"] == "agent-context"
+        assert manifest["extension"]["name"] == "Coding Agent Context"
+        assert manifest["extension"]["author"] == "spec-kit-core"
+        # Provides at least the manual update command
+        commands = {c["name"] for c in manifest["provides"]["commands"]}
+        assert "speckit.agent-context.update" in commands
+
+    def test_readme_exists(self):
+        readme = EXT_DIR / "README.md"
+        assert readme.is_file()
+        text = readme.read_text(encoding="utf-8")
+        assert "Coding Agent Context Extension" in text
+
+    def test_config_template_exists(self):
+        cfg = EXT_DIR / "agent-context-config.yml"
+        assert cfg.is_file()
+        parsed = yaml.safe_load(cfg.read_text(encoding="utf-8"))
+        assert "context_file" in parsed
+        assert "context_markers" in parsed
+
+    def test_command_file_exists(self):
+        cmd = EXT_DIR / "commands" / "speckit.agent-context.update.md"
+        assert cmd.is_file()
+        assert "agent-context-config.yml" in cmd.read_text(encoding="utf-8")
+
+    def test_bundled_scripts_exist(self):
+        assert (EXT_DIR / "scripts" / "bash" / "update-agent-context.sh").is_file()
+        assert (EXT_DIR / "scripts" / "powershell" / "update-agent-context.ps1").is_file()
+
+    def test_bash_script_reads_extension_config(self):
+        text = (EXT_DIR / "scripts" / "bash" / "update-agent-context.sh").read_text(
+            encoding="utf-8"
+        )
+        # The script must consult the extension config, not init-options.json
+        assert "agent-context-config.yml" in text
+        assert "context_file" in text
+        assert "context_markers" in text
+
+
+# ── Catalog registration ─────────────────────────────────────────────────────
+
+
+class TestCatalogEntry:
+    def test_catalog_lists_agent_context_as_bundled(self):
+        catalog = json.loads(
+            (PROJECT_ROOT / "extensions" / "catalog.json").read_text(encoding="utf-8")
+        )
+        entry = catalog["extensions"]["agent-context"]
+        assert entry["bundled"] is True
+        assert entry["id"] == "agent-context"
+        assert entry["author"] == "spec-kit-core"
+
+
+# ── Marker resolution from extension config ──────────────────────────────────
+
+
+class _CtxIntegration(ClaudeIntegration):
+    """Use Claude as a concrete integration with a context_file."""
+
+
+class TestContextMarkerResolution:
+    def test_defaults_when_ext_config_missing(self, tmp_path):
+        i = _CtxIntegration()
+        start, end = i._resolve_context_markers(tmp_path)
+        assert start == IntegrationBase.CONTEXT_MARKER_START
+        assert end == IntegrationBase.CONTEXT_MARKER_END
+
+    def test_defaults_when_markers_field_missing(self, tmp_path):
+        _write_ext_config(tmp_path, context_file="CLAUDE.md")
+        i = _CtxIntegration()
+        start, end = i._resolve_context_markers(tmp_path)
+        assert start == IntegrationBase.CONTEXT_MARKER_START
+        assert end == IntegrationBase.CONTEXT_MARKER_END
+
+    def test_custom_markers_respected(self, tmp_path):
+        _write_ext_config(
+            tmp_path,
+            context_markers={"start": "<!-- BEGIN -->", "end": "<!-- END -->"},
+        )
+        i = _CtxIntegration()
+        start, end = i._resolve_context_markers(tmp_path)
+        assert start == "<!-- BEGIN -->"
+        assert end == "<!-- END -->"
+
+    def test_partial_override_falls_back_for_missing_side(self, tmp_path):
+        _write_ext_config(tmp_path, context_markers={"start": "<!-- ONLY START -->"})
+        i = _CtxIntegration()
+        start, end = i._resolve_context_markers(tmp_path)
+        assert start == "<!-- ONLY START -->"
+        assert end == IntegrationBase.CONTEXT_MARKER_END
+
+    def test_invalid_markers_fall_back(self, tmp_path):
+        _write_ext_config(tmp_path, context_markers={"start": 42, "end": ""})
+        i = _CtxIntegration()
+        start, end = i._resolve_context_markers(tmp_path)
+        assert start == IntegrationBase.CONTEXT_MARKER_START
+        assert end == IntegrationBase.CONTEXT_MARKER_END
+
+
+# ── upsert_context_section / remove_context_section honor markers ───────────
+
+
+class TestUpsertWithCustomMarkers:
+    def _setup(self, tmp_path: Path, markers: dict | None = None) -> _CtxIntegration:
+        _write_ext_config(
+            tmp_path,
+            context_file="CLAUDE.md",
+            **({"context_markers": markers} if markers is not None else {}),
+        )
+        return _CtxIntegration()
+
+    def test_upsert_uses_default_markers(self, tmp_path):
+        i = self._setup(tmp_path)
+        result = i.upsert_context_section(tmp_path)
+        assert result is not None
+        text = (tmp_path / "CLAUDE.md").read_text(encoding="utf-8")
+        assert IntegrationBase.CONTEXT_MARKER_START in text
+        assert IntegrationBase.CONTEXT_MARKER_END in text
+
+    def test_upsert_uses_custom_markers(self, tmp_path):
+        i = self._setup(
+            tmp_path, {"start": "<!-- BEGIN -->", "end": "<!-- END -->"}
+        )
+        i.upsert_context_section(tmp_path)
+        text = (tmp_path / "CLAUDE.md").read_text(encoding="utf-8")
+        assert "<!-- BEGIN -->" in text
+        assert "<!-- END -->" in text
+        # Defaults must not appear
+        assert IntegrationBase.CONTEXT_MARKER_START not in text
+        assert IntegrationBase.CONTEXT_MARKER_END not in text
+
+    def test_upsert_replaces_existing_custom_section(self, tmp_path):
+        i = self._setup(
+            tmp_path, {"start": "<!-- BEGIN -->", "end": "<!-- END -->"}
+        )
+        ctx = tmp_path / "CLAUDE.md"
+        ctx.write_text(
+            "# header\n\n<!-- BEGIN -->\nold body\n<!-- END -->\n\nfooter\n",
+            encoding="utf-8",
+        )
+        i.upsert_context_section(tmp_path, plan_path="specs/001-foo/plan.md")
+        text = ctx.read_text(encoding="utf-8")
+        assert "old body" not in text
+        assert "specs/001-foo/plan.md" in text
+        assert text.startswith("# header\n")
+        assert "footer" in text
+
+    def test_remove_uses_custom_markers(self, tmp_path):
+        i = self._setup(
+            tmp_path, {"start": "<!-- BEGIN -->", "end": "<!-- END -->"}
+        )
+        ctx = tmp_path / "CLAUDE.md"
+        ctx.write_text(
+            "preamble\n\n<!-- BEGIN -->\nbody\n<!-- END -->\nepilogue\n",
+            encoding="utf-8",
+        )
+        removed = i.remove_context_section(tmp_path)
+        assert removed is True
+        remaining = ctx.read_text(encoding="utf-8")
+        assert "<!-- BEGIN -->" not in remaining
+        assert "<!-- END -->" not in remaining
+        assert "body" not in remaining
+        assert "preamble" in remaining
+        assert "epilogue" in remaining
+
+    def test_remove_with_default_markers_unchanged_when_custom_in_file(self, tmp_path):
+        # Extension config absent → default markers used. File contains only
+        # custom markers — nothing should be removed.
+        i = _CtxIntegration()
+        ctx = tmp_path / "CLAUDE.md"
+        original = "x\n<!-- BEGIN -->\nbody\n<!-- END -->\n"
+        ctx.write_text(original, encoding="utf-8")
+        assert i.remove_context_section(tmp_path) is False
+        assert ctx.read_text(encoding="utf-8") == original
+
+
+# ── Extension disabled gates setup/teardown ──────────────────────────────────
+
+
+def _write_registry(project_root: Path, *, enabled: bool) -> None:
+    registry = project_root / ".specify" / "extensions" / ".registry"
+    registry.parent.mkdir(parents=True, exist_ok=True)
+    registry.write_text(
+        json.dumps(
+            {
+                "schema_version": "1.0",
+                "extensions": {
+                    "agent-context": {
+                        "version": "1.0.0",
+                        "enabled": enabled,
+                    }
+                },
+            }
+        ),
+        encoding="utf-8",
+    )
+
+
+class TestExtensionEnabledGate:
+    def test_enabled_helper_default_when_no_registry(self, tmp_path):
+        assert IntegrationBase._agent_context_extension_enabled(tmp_path) is True
+
+    def test_enabled_helper_when_entry_present(self, tmp_path):
+        _write_registry(tmp_path, enabled=True)
+        assert IntegrationBase._agent_context_extension_enabled(tmp_path) is True
+
+    def test_disabled_helper_when_entry_disabled(self, tmp_path):
+        _write_registry(tmp_path, enabled=False)
+        assert IntegrationBase._agent_context_extension_enabled(tmp_path) is False
+
+    def test_upsert_skipped_when_disabled(self, tmp_path):
+        _write_registry(tmp_path, enabled=False)
+        i = _CtxIntegration()
+        result = i.upsert_context_section(tmp_path)
+        assert result is None
+        assert not (tmp_path / "CLAUDE.md").exists()
+
+    def test_remove_skipped_when_disabled(self, tmp_path):
+        _write_registry(tmp_path, enabled=False)
+        i = _CtxIntegration()
+        ctx = tmp_path / "CLAUDE.md"
+        original = (
+            f"head\n{IntegrationBase.CONTEXT_MARKER_START}\nbody\n"
+            f"{IntegrationBase.CONTEXT_MARKER_END}\ntail\n"
+        )
+        ctx.write_text(original, encoding="utf-8")
+        assert i.remove_context_section(tmp_path) is False
+        # File must be unchanged when extension is disabled
+        assert ctx.read_text(encoding="utf-8") == original
+
+
+# ── Extension config writers ─────────────────────────────────────────────────
+
+
+class TestExtensionConfigWriters:
+    def test_clear_init_options_clears_ext_config_context_file(self, tmp_path):
+        from specify_cli import _clear_init_options_for_integration
+
+        save_init_options(
+            tmp_path,
+            {"integration": "claude", "ai": "claude"},
+        )
+        _write_ext_config(tmp_path, context_file="CLAUDE.md")
+        _clear_init_options_for_integration(tmp_path, "claude")
+        cfg = _load_agent_context_config(tmp_path)
+        assert cfg.get("context_file") == ""
+
+    def test_clear_init_options_creates_ext_config_when_missing(self, tmp_path):
+        from specify_cli import _clear_init_options_for_integration
+
+        save_init_options(
+            tmp_path,
+            {"integration": "claude", "ai": "claude"},
+        )
+        _clear_init_options_for_integration(tmp_path, "claude")
+        cfg = _load_agent_context_config(tmp_path)
+        assert cfg.get("context_file") == ""
+
+    def test_clear_init_options_removes_legacy_context_keys_even_when_not_active(
+        self, tmp_path
+    ):
+        from specify_cli import _clear_init_options_for_integration
+
+        save_init_options(
+            tmp_path,
+            {
+                "integration": "copilot",
+                "ai": "copilot",
+                "context_file": "CLAUDE.md",
+                "context_markers": {"start": "<!-- X -->", "end": "<!-- Y -->"},
+            },
+        )
+        _clear_init_options_for_integration(tmp_path, "claude")
+        opts = load_init_options(tmp_path)
+        assert opts["integration"] == "copilot"
+        assert opts["ai"] == "copilot"
+        assert "context_file" not in opts
+        assert "context_markers" not in opts
+
+    def test_update_init_options_writes_context_file_to_ext_config(self, tmp_path):
+        from specify_cli import _update_init_options_for_integration
+
+        # Pre-create the extension config so _update_init_options_for_integration
+        # updates it (rather than skipping it when ext config doesn't exist yet).
+        _write_ext_config(tmp_path, context_file="")
+        i = _CtxIntegration()
+        _update_init_options_for_integration(tmp_path, i, script_type="sh")
+        # init-options.json must NOT have context_file or context_markers
+        opts = load_init_options(tmp_path)
+        assert "context_file" not in opts
+        assert "context_markers" not in opts
+        # Extension config must have them
+        cfg = _load_agent_context_config(tmp_path)
+        assert cfg["context_file"] == i.context_file
+        assert "context_markers" in cfg
+
+    def test_update_init_options_preserves_custom_markers(self, tmp_path):
+        from specify_cli import _update_init_options_for_integration
+
+        _write_ext_config(
+            tmp_path,
+            context_file="",
+            context_markers={"start": "<!-- B -->", "end": "<!-- E -->"},
+        )
+        i = _CtxIntegration()
+        _update_init_options_for_integration(tmp_path, i)
+        cfg = _load_agent_context_config(tmp_path)
+        assert cfg["context_markers"] == {"start": "<!-- B -->", "end": "<!-- E -->"}
+
+    def test_reinit_preserves_custom_markers(self, tmp_path):
+        """specify init (reinit) must not overwrite user-customised markers."""
+        from specify_cli import _update_agent_context_config_file
+
+        # Simulate existing project with custom markers
+        _write_ext_config(
+            tmp_path,
+            context_file="CLAUDE.md",
+            context_markers={"start": "<!-- CUSTOM -->", "end": "<!-- /CUSTOM -->"},
+        )
+        # Re-running init updates context_file but must preserve markers
+        _update_agent_context_config_file(
+            tmp_path, "CLAUDE.md", preserve_markers=True
+        )
+        cfg = _load_agent_context_config(tmp_path)
+        assert cfg["context_markers"] == {
+            "start": "<!-- CUSTOM -->",
+            "end": "<!-- /CUSTOM -->",
+        }
diff --git a/tests/integrations/test_cli.py b/tests/integrations/test_cli.py
index de09205310..12fa6c7351 100644
--- a/tests/integrations/test_cli.py
+++ b/tests/integrations/test_cli.py
@@ -67,7 +67,14 @@ def test_integration_copilot_creates_files(self, tmp_path):
 
         opts = json.loads((project / ".specify" / "init-options.json").read_text(encoding="utf-8"))
         assert opts["integration"] == "copilot"
-        assert opts["context_file"] == ".github/copilot-instructions.md"
+        # context_file lives in the agent-context extension config, not init-options.json
+        assert "context_file" not in opts
+
+        import yaml as _yaml
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        assert ext_cfg_path.exists(), "agent-context extension config must be created on init"
+        ext_cfg = _yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8"))
+        assert ext_cfg["context_file"] == ".github/copilot-instructions.md"
 
         assert (project / ".specify" / "integrations" / "copilot.manifest.json").exists()
 
diff --git a/tests/integrations/test_integration_base_markdown.py b/tests/integrations/test_integration_base_markdown.py
index 0b74a6f1a9..1ba407a820 100644
--- a/tests/integrations/test_integration_base_markdown.py
+++ b/tests/integrations/test_integration_base_markdown.py
@@ -226,8 +226,8 @@ def test_integration_flag_creates_files(self, tmp_path):
         assert len(commands) > 0, f"No command files in {cmd_dir}"
 
     def test_init_options_includes_context_file(self, tmp_path):
-        """init-options.json must include context_file for the active integration."""
-        import json
+        """agent-context extension config must include context_file for the active integration."""
+        import yaml
         from typer.testing import CliRunner
         from specify_cli import app
 
@@ -243,10 +243,11 @@ def test_init_options_includes_context_file(self, tmp_path):
         finally:
             os.chdir(old_cwd)
         assert result.exit_code == 0
-        opts = json.loads((project / ".specify" / "init-options.json").read_text())
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        ext_cfg = yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8")) if ext_cfg_path.exists() else {}
         i = get_integration(self.KEY)
-        assert opts.get("context_file") == i.context_file, (
-            f"Expected context_file={i.context_file!r}, got {opts.get('context_file')!r}"
+        assert ext_cfg.get("context_file") == i.context_file, (
+            f"Expected context_file={i.context_file!r}, got {ext_cfg.get('context_file')!r}"
         )
 
     # -- Complete file inventory ------------------------------------------
@@ -291,6 +292,9 @@ def _expected_files(self, script_variant: str) -> list[str]:
         files.append(".specify/workflows/speckit/workflow.yml")
         files.append(".specify/workflows/workflow-registry.json")
 
+        # Agent context extension config
+        files.append(".specify/extensions/agent-context/agent-context-config.yml")
+
         # Agent context file (if set)
         if i.context_file:
             files.append(i.context_file)
diff --git a/tests/integrations/test_integration_base_skills.py b/tests/integrations/test_integration_base_skills.py
index 89140de1c3..6fd1a0cf19 100644
--- a/tests/integrations/test_integration_base_skills.py
+++ b/tests/integrations/test_integration_base_skills.py
@@ -324,8 +324,8 @@ def test_integration_flag_creates_files(self, tmp_path):
         assert skills_dir.is_dir(), f"Skills directory {skills_dir} not created"
 
     def test_init_options_includes_context_file(self, tmp_path):
-        """init-options.json must include context_file for the active integration."""
-        import json
+        """agent-context extension config must include context_file for the active integration."""
+        import yaml
         from typer.testing import CliRunner
         from specify_cli import app
 
@@ -341,10 +341,11 @@ def test_init_options_includes_context_file(self, tmp_path):
         finally:
             os.chdir(old_cwd)
         assert result.exit_code == 0
-        opts = json.loads((project / ".specify" / "init-options.json").read_text())
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        ext_cfg = yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8")) if ext_cfg_path.exists() else {}
         i = get_integration(self.KEY)
-        assert opts.get("context_file") == i.context_file, (
-            f"Expected context_file={i.context_file!r}, got {opts.get('context_file')!r}"
+        assert ext_cfg.get("context_file") == i.context_file, (
+            f"Expected context_file={i.context_file!r}, got {ext_cfg.get('context_file')!r}"
         )
 
     # -- IntegrationOption ------------------------------------------------
@@ -410,6 +411,8 @@ def _expected_files(self, script_variant: str) -> list[str]:
             ".specify/workflows/speckit/workflow.yml",
             ".specify/workflows/workflow-registry.json",
         ]
+        # Agent context extension config
+        files.append(".specify/extensions/agent-context/agent-context-config.yml")
         # Agent context file (if set)
         if i.context_file:
             files.append(i.context_file)
diff --git a/tests/integrations/test_integration_base_toml.py b/tests/integrations/test_integration_base_toml.py
index 56862e534c..1dac629d02 100644
--- a/tests/integrations/test_integration_base_toml.py
+++ b/tests/integrations/test_integration_base_toml.py
@@ -457,8 +457,8 @@ def test_integration_flag_creates_files(self, tmp_path):
         assert len(commands) > 0, f"No command files in {cmd_dir}"
 
     def test_init_options_includes_context_file(self, tmp_path):
-        """init-options.json must include context_file for the active integration."""
-        import json
+        """agent-context extension config must include context_file for the active integration."""
+        import yaml
         from typer.testing import CliRunner
         from specify_cli import app
 
@@ -474,10 +474,11 @@ def test_init_options_includes_context_file(self, tmp_path):
         finally:
             os.chdir(old_cwd)
         assert result.exit_code == 0
-        opts = json.loads((project / ".specify" / "init-options.json").read_text())
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        ext_cfg = yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8")) if ext_cfg_path.exists() else {}
         i = get_integration(self.KEY)
-        assert opts.get("context_file") == i.context_file, (
-            f"Expected context_file={i.context_file!r}, got {opts.get('context_file')!r}"
+        assert ext_cfg.get("context_file") == i.context_file, (
+            f"Expected context_file={i.context_file!r}, got {ext_cfg.get('context_file')!r}"
         )
 
     # -- Complete file inventory ------------------------------------------
@@ -543,6 +544,9 @@ def _expected_files(self, script_variant: str) -> list[str]:
         files.append(".specify/workflows/speckit/workflow.yml")
         files.append(".specify/workflows/workflow-registry.json")
 
+        # Agent context extension config
+        files.append(".specify/extensions/agent-context/agent-context-config.yml")
+
         # Agent context file (if set)
         if i.context_file:
             files.append(i.context_file)
diff --git a/tests/integrations/test_integration_base_yaml.py b/tests/integrations/test_integration_base_yaml.py
index 956c7a796f..d0e808ef46 100644
--- a/tests/integrations/test_integration_base_yaml.py
+++ b/tests/integrations/test_integration_base_yaml.py
@@ -336,8 +336,8 @@ def test_integration_flag_creates_files(self, tmp_path):
         assert len(commands) > 0, f"No command files in {cmd_dir}"
 
     def test_init_options_includes_context_file(self, tmp_path):
-        """init-options.json must include context_file for the active integration."""
-        import json
+        """agent-context extension config must include context_file for the active integration."""
+        import yaml
         from typer.testing import CliRunner
         from specify_cli import app
 
@@ -353,10 +353,11 @@ def test_init_options_includes_context_file(self, tmp_path):
         finally:
             os.chdir(old_cwd)
         assert result.exit_code == 0
-        opts = json.loads((project / ".specify" / "init-options.json").read_text())
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        ext_cfg = yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8")) if ext_cfg_path.exists() else {}
         i = get_integration(self.KEY)
-        assert opts.get("context_file") == i.context_file, (
-            f"Expected context_file={i.context_file!r}, got {opts.get('context_file')!r}"
+        assert ext_cfg.get("context_file") == i.context_file, (
+            f"Expected context_file={i.context_file!r}, got {ext_cfg.get('context_file')!r}"
         )
 
     # -- Complete file inventory ------------------------------------------
@@ -422,6 +423,9 @@ def _expected_files(self, script_variant: str) -> list[str]:
         files.append(".specify/workflows/speckit/workflow.yml")
         files.append(".specify/workflows/workflow-registry.json")
 
+        # Agent context extension config
+        files.append(".specify/extensions/agent-context/agent-context-config.yml")
+
         # Agent context file (if set)
         if i.context_file:
             files.append(i.context_file)
diff --git a/tests/integrations/test_integration_copilot.py b/tests/integrations/test_integration_copilot.py
index c6e9259b09..664ce0d59a 100644
--- a/tests/integrations/test_integration_copilot.py
+++ b/tests/integrations/test_integration_copilot.py
@@ -198,6 +198,7 @@ def test_complete_file_inventory_sh(self, tmp_path):
             ".github/prompts/speckit.taskstoissues.prompt.md",
             ".vscode/settings.json",
             ".github/copilot-instructions.md",
+            ".specify/extensions/agent-context/agent-context-config.yml",
             ".specify/integration.json",
             ".specify/init-options.json",
             ".specify/integrations/copilot.manifest.json",
@@ -258,6 +259,7 @@ def test_complete_file_inventory_ps(self, tmp_path):
             ".github/prompts/speckit.taskstoissues.prompt.md",
             ".vscode/settings.json",
             ".github/copilot-instructions.md",
+            ".specify/extensions/agent-context/agent-context-config.yml",
             ".specify/integration.json",
             ".specify/init-options.json",
             ".specify/integrations/copilot.manifest.json",
@@ -606,6 +608,8 @@ def test_complete_file_inventory_skills_sh(self, tmp_path):
             *[f".github/skills/speckit-{cmd}/SKILL.md" for cmd in self._SKILL_COMMANDS],
             # Context file
             ".github/copilot-instructions.md",
+            # Agent context extension config
+            ".specify/extensions/agent-context/agent-context-config.yml",
             # Integration metadata
             ".specify/init-options.json",
             ".specify/integration.json",
diff --git a/tests/integrations/test_integration_generic.py b/tests/integrations/test_integration_generic.py
index 4f515a01d2..9175ff1303 100644
--- a/tests/integrations/test_integration_generic.py
+++ b/tests/integrations/test_integration_generic.py
@@ -211,8 +211,8 @@ def test_cli_generic_without_commands_dir_fails(self, tmp_path):
         assert result.exit_code != 0
 
     def test_init_options_includes_context_file(self, tmp_path):
-        """init-options.json must include context_file for the generic integration."""
-        import json
+        """agent-context extension config must include context_file for the generic integration."""
+        import yaml
         from typer.testing import CliRunner
         from specify_cli import app
 
@@ -229,8 +229,9 @@ def test_init_options_includes_context_file(self, tmp_path):
         finally:
             os.chdir(old_cwd)
         assert result.exit_code == 0
-        opts = json.loads((project / ".specify" / "init-options.json").read_text())
-        assert opts.get("context_file") == "AGENTS.md"
+        ext_cfg_path = project / ".specify" / "extensions" / "agent-context" / "agent-context-config.yml"
+        ext_cfg = yaml.safe_load(ext_cfg_path.read_text(encoding="utf-8")) if ext_cfg_path.exists() else {}
+        assert ext_cfg.get("context_file") == "AGENTS.md"
 
     def test_complete_file_inventory_sh(self, tmp_path):
         """Every file produced by specify init --integration generic --ai-commands-dir ... --script sh."""
@@ -265,6 +266,7 @@ def test_complete_file_inventory_sh(self, tmp_path):
             ".myagent/commands/speckit.specify.md",
             ".myagent/commands/speckit.tasks.md",
             ".myagent/commands/speckit.taskstoissues.md",
+            ".specify/extensions/agent-context/agent-context-config.yml",
             ".specify/init-options.json",
             ".specify/integration.json",
             ".specify/integrations/generic.manifest.json",
@@ -321,6 +323,7 @@ def test_complete_file_inventory_ps(self, tmp_path):
             ".myagent/commands/speckit.specify.md",
             ".myagent/commands/speckit.tasks.md",
             ".myagent/commands/speckit.taskstoissues.md",
+            ".specify/extensions/agent-context/agent-context-config.yml",
             ".specify/init-options.json",
             ".specify/integration.json",
             ".specify/integrations/generic.manifest.json",