Merge pull request #5 from mtsfoni/copilot/remove-watermark-from-commits

Remove "Generated by construct" watermark from git commits

Author: mtsfoni

CHANGELOG.md

@@ -75,9 +75,6 @@
   the committer falls back to the author (matching git's default behaviour). The
   synthetic fallback (`construct user <user@construct.local>`) is only used when
   no author identity at all is available on the host, and triggers a warning.
-- A `commit-msg` hook is injected into the container at startup via
-  `core.hooksPath`. It appends a `Generated by construct` git trailer to every
-  commit message (idempotent — safe with amend and rebase).
 
 ---
 

docs/spec/construct-agents-md.md

@@ -90,7 +90,7 @@ not override a project-level `AGENTS.md` or `CLAUDE.md` in the workspace.
 
 | File | Change |
 |---|---|
-| `internal/runner/runner.go` | `CONSTRUCT=1` always injected; `generatedEntrypoint()` always writes `~/.config/opencode/AGENTS.md`, appending port rules only when `CONSTRUCT_PORTS` is set; also writes git identity hook and sets `core.hooksPath` (see `docs/spec/git-identity.md`) |
+| `internal/runner/runner.go` | `CONSTRUCT=1` always injected; `generatedEntrypoint()` always writes `~/.config/opencode/AGENTS.md`, appending port rules only when `CONSTRUCT_PORTS` is set |
 | `internal/runner/runner_test.go` | Tests updated to reflect always-present `CONSTRUCT=1` and always-present `AGENTS.md` |
 | `docs/spec/construct-agents-md.md` | This document |
 

docs/spec/git-identity.md

@@ -10,9 +10,7 @@ attribution that comes from the developer's own git identity.
 ## Solution
 
 construct reads the host user's git identity at launch and injects it into the
-container. Every commit the agent makes is attributed to the real developer. A
-`commit-msg` hook appended to every commit message makes it clear the commit was
-generated by construct.
+container. Every commit the agent makes is attributed to the real developer.
 
 ## Behaviour
 
@@ -60,37 +58,7 @@ GIT_COMMITTER_EMAIL=<resolved>
 The previous hard-coded `construct agent / agent@construct.local` identity is
 removed entirely.
 
-### 3. Commit-msg hook
-
-`generatedEntrypoint()` writes a `commit-msg` hook into the container at
-startup:
-
-```
-/home/agent/.githooks/commit-msg
-```
-
-and configures git to use it globally:
-
-```sh
-git config --global core.hooksPath /home/agent/.githooks
-```
-
-The hook appends a `Generated by construct` trailer to every commit message,
-following the git trailer convention (a blank line separates the body from the
-trailer block). The hook is idempotent: it checks for the presence of the
-trailer before appending, so amend and rebase do not produce duplicates.
-
-Resulting commit message format:
-
-```
-feat: add user login
-
-Implement OAuth2 flow with token refresh.
-
-Generated by construct
-```
-
-### 4. Scope
+### 3. Scope
 
 This is a runner-level change. It applies to all tools.
 
@@ -104,7 +72,7 @@ No files are written to the host or to the workspace repo.
 
 | File | Change |
 |---|---|
-| `internal/runner/runner.go` | `hostGitIdentity()`: resolves author/committer separately, honouring host env vars with committer falling back to author; `buildRunArgs`: injects resolved values; `generatedEntrypoint()`: writes `/home/agent/.githooks/commit-msg` and sets `git config --global core.hooksPath` |
+| `internal/runner/runner.go` | `hostGitIdentity()`: resolves author/committer separately, honouring host env vars with committer falling back to author; `buildRunArgs`: injects resolved values |
 | `docs/spec/git-identity.md` | This document |
 | `CHANGELOG.md` | Entry under `## [Unreleased]` |
 

docs/spec/image-build-layers.md

@@ -82,10 +82,7 @@ off to the tool:
    `~/.config/opencode/opencode.json` with the playwright MCP server entry.
    Otherwise deletes the file, preventing stale config from persisting across
    runs on the same home volume.
-3. **Git identity** — sets `git config --global core.hooksPath
-   /home/agent/.githooks` and writes a `commit-msg` hook that appends a
-   `Generated by construct` trailer to every commit message (idempotent).
-   The host user's git identity is supplied via `GIT_AUTHOR_*` /
+3. **Git identity** — the host user's git identity is supplied via `GIT_AUTHOR_*` /
    `GIT_COMMITTER_*` env vars set in `buildRunArgs` (see
    `docs/spec/git-identity.md`).
 4. **Exec** — hands off to the tool command (`exec "$@"`).
@@ -109,7 +106,6 @@ Examples: `construct-ui-opencode`, `construct-go-opencode`.
 | AI tool binary (`npm install -g opencode-ai`) | Tool |
 | Entrypoint / secrets handling | Tool |
 | MCP config write/delete logic | Tool (entrypoint) |
-| Git identity hook (`commit-msg`, `core.hooksPath`) | Tool (entrypoint) |
 | `DOCKER_HOST` env var (runtime, not baked in) | Container run args |
 | Git author/committer identity (host-read at launch) | Container run args |
 | Workspace bind-mount | Container run args |

docs/threat-model.md

@@ -179,7 +179,7 @@ The agent does **not** have access to:
 | **Mitigation** | No git credential helper is wired up by construct. The agent would have to discover the token from its environment and construct the remote URL manually (e.g. `https://x-access-token:$TOKEN@github.com/...`). This is non-trivial but not difficult for a capable model. SSH keys are **not** mounted into the container, so SSH-based remotes are unreachable. |
 | **Residual risk** | No token with git push scope is injected by default. If a user supplies a GitHub token via `config set`, the agent could use it for HTTPS git operations. |
 | **Recommendation** | Use a token scoped to the minimum required permissions. A GitHub fine-grained PAT with read-only or repo-specific access limits blast radius. Avoid using tokens that have push access to repositories beyond the one you are actively working on. Note: recommending SSH remotes is **not** a useful mitigation here — SSH keys are not mounted, so the attack surface is HTTPS+token only. |
-| **Attribution note** | construct injects the host user's real git identity (`user.name` / `user.email`) as `GIT_AUTHOR_*` and `GIT_COMMITTER_*`. Any commits the agent makes — including any it pushes — will carry the developer's real name and email, plus a `Generated by construct` trailer. Users should be aware that agent-authored commits are attributable to them in git history. |
+| **Attribution note** | construct injects the host user's real git identity (`user.name` / `user.email`) as `GIT_AUTHOR_*` and `GIT_COMMITTER_*`. Any commits the agent makes — including any it pushes — will carry the developer's real name and email. Users should be aware that agent-authored commits are attributable to them in git history. |
 | **vs. host baseline** | On the host, the agent has access to the user's full git credential store (`~/.gitconfig`, credential helper, SSH keys, `~/.netrc`), giving push access to every repository the user can reach. construct limits this to explicitly injected tokens only. |
 
 ---

internal/runner/runner.go

@@ -280,8 +280,7 @@ func buildRunArgs(cfg *Config, dindInst *dind.Instance, image, sessionID, homeVo
 		// Git identity — use the host user's real identity so commits are attributed
 		// to the person who ran construct. Author and committer are read separately
 		// so that a host with distinct GIT_AUTHOR_* / GIT_COMMITTER_* env vars is
-		// faithfully mirrored. The commit-msg hook (written by the entrypoint)
-		// appends a "Generated by construct" trailer to every message.
+		// faithfully mirrored.
 		"-e", "GIT_AUTHOR_NAME="+authorName,
 		"-e", "GIT_AUTHOR_EMAIL="+authorEmail,
 		"-e", "GIT_COMMITTER_NAME="+committerName,
@@ -936,19 +935,6 @@ func generatedEntrypoint() string {
 		"The host connects to it via http://localhost:${CONSTRUCT_SERVE_PORT}.\n" +
 		"AGENTSEOF\n" +
 		"fi\n" +
-		"# Set up a global commit-msg hook that appends a 'Generated by construct'\n" +
-		"# git trailer to every commit message. The hook is idempotent: it checks for\n" +
-		"# the trailer before appending so amend/rebase does not produce duplicates.\n" +
-		"mkdir -p \"${HOME}/.githooks\"\n" +
-		"cat > \"${HOME}/.githooks/commit-msg\" << 'HOOKEOF'\n" +
-		"#!/bin/sh\n" +
-		"trailer='Generated by construct'\n" +
-		"if ! grep -qF \"$trailer\" \"$1\"; then\n" +
-		"  printf '\\n%s\\n' \"$trailer\" >> \"$1\"\n" +
-		"fi\n" +
-		"HOOKEOF\n" +
-		"chmod +x \"${HOME}/.githooks/commit-msg\"\n" +
-		"git config --global core.hooksPath \"${HOME}/.githooks\"\n" +
 		"exec \"$@\"\n"
 }
 

internal/runner/runner_test.go

@@ -1609,42 +1609,12 @@ func TestHostGitIdentity_CommitterFallsBackToAuthor(t *testing.T) {
 	}
 }
 
-// TestGeneratedEntrypoint_ContainsCommitMsgHook verifies that the generated
-// entrypoint script sets up the commit-msg hook and configures core.hooksPath.
-func TestGeneratedEntrypoint_ContainsCommitMsgHook(t *testing.T) {
+// TestGeneratedEntrypoint_EndsWithExec verifies that the generated entrypoint
+// script ends with exec "$@".
+func TestGeneratedEntrypoint_EndsWithExec(t *testing.T) {
 	script := generatedEntrypoint()
-	checks := []struct {
-		desc    string
-		snippet string
-	}{
-		{"creates .githooks dir", ".githooks"},
-		{"writes commit-msg hook file", "commit-msg"},
-		{"hook appends Generated by construct trailer", "Generated by construct"},
-		{"hook is idempotent (grep check)", "grep -qF"},
-		{"sets core.hooksPath globally", "core.hooksPath"},
-		{"hook is executable", "chmod +x"},
-	}
-	for _, c := range checks {
-		if !strings.Contains(script, c.snippet) {
-			t.Errorf("entrypoint: expected %s (snippet %q not found)", c.desc, c.snippet)
-		}
-	}
-}
-
-// TestGeneratedEntrypoint_HookBeforeExec verifies the commit-msg hook setup
-// appears before the final exec line.
-func TestGeneratedEntrypoint_HookBeforeExec(t *testing.T) {
-	script := generatedEntrypoint()
-	hookIdx := strings.Index(script, "commit-msg")
-	execIdx := strings.LastIndex(script, `exec "$@"`)
-	if hookIdx == -1 {
-		t.Fatal("commit-msg hook block not found in entrypoint")
-	}
-	if execIdx == -1 {
-		t.Fatal(`exec "$@" not found in entrypoint`)
-	}
-	if hookIdx > execIdx {
-		t.Error("commit-msg hook block appears after exec line; it must come before")
+	if !strings.Contains(script, `exec "$@"`) {
+		t.Error(`entrypoint: expected exec "$@" line not found`)
 	}
 }