Compare-to-commit: native multi-diff file experience + commit-graph menu fixes

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "basilisk.enabled": true,
+    "basilisk.uv.enabled": true,
+    "basilisk.aiTyping.enabled": false
+}

CLAUDE.md

@@ -4,20 +4,21 @@
 
 ⚠️ DO NOT KILL VSCODE PROCESSES ⚠️
 
+⚠️ ASKING THE USER QUESTIONS IS ⛔️ ILLEGAL. USE YOUR JUDGEMENT ⚠️
+
 ⚠️ **TOKEN DISCIPLINE.** Check file size first. `Grep` over `Read`. Use `offset`/`limit`.
 Smallest diff that solves the problem. Delete dead code, unused imports, stale comments.
 Call out irrelevant context before proceeding. Bloat degrades reasoning. ⚠️
 
 ⚠️ **CRITICAL: THIS CODEBASE RECEIVES A GRADE OF A+.** WE DON'T ALLOW BAD CODE. NOT EVEN FOR ONE LINE. CODE MUST PASS REVIEW AT Google / Meta / Microsoft. ANYTHING LESS IS ⛔️ ILLEGAL AND MUST BE FIXED IMMEDIATELY.⚠️
 
-⚠️ **NEW VIEWS, ACTIVITY-BAR ICONS, SIDEBARS, TREE PROVIDERS, OR WEBVIEWS ARE ⛔️ ILLEGAL.**
-Diffr is **context-menu only**. Every feature hangs off VSCode's existing SCM history, SCM resource state, editor title, and explorer menus — plus a small set of palette commands. If a feature needs a new panel to exist, the feature is wrong.⚠️
+⚠️ **KEEP THE UI MINIMAL.** Default to VSCode's existing surfaces — SCM history, SCM resource state, editor title, and explorer context menus, plus a small set of palette commands. Avoid building new views, sidebars, activity-bar icons, tree providers, or webviews **unless the UI is an integral part of the flow** and no built-in surface can carry it well. When custom UI does earn its place, it must be first-class — not a half-measure bolted onto a picker.⚠️
 
 Full design + execution plan: [spec.md](spec.md).
 
 ## Project Overview
 
-**Diffr** is a VSCode extension that does exactly one thing: **pick two things and diff them** against a git repository. Side A is a commit; Side B is another commit, the working copy, the index, or a branch/tag (resolved to a commit). It shells out to `git`, hands two URIs to VSCode's built-in `vscode.diff`, and uses a multi-step QuickPick for browsing many changed files. No custom renderer, no custom view.
+**Diffr** is a VSCode extension that does exactly one thing: **pick two things and diff them** against a git repository. Side A is a commit; Side B is another commit, the working copy, the index, or a branch/tag (resolved to a commit). It shells out to `git`, hands two URIs to VSCode's built-in `vscode.diff`, and browses many changed files through a focused selection UI. The UI stays minimal — built-in surfaces first, purpose-built UI only when it's integral to the flow.
 
 **Primary language:** TypeScript (pure — Rust LSP was considered and rejected; LSP is for _language_ semantics, not diffing)
 **Build command:** `make ci`
@@ -46,7 +47,7 @@ context-menu / palette command
 ## Hard Rules (no exceptions, NON-NEGOTIABLE)
 
 - **NO git commands from the agent.** No `git add`, `commit`, `push`, `checkout`, `merge`, `rebase`. CI and GitHub Actions handle git. (Diffr itself shells out to `git` at runtime — that's the product. The _agent_ doesn't drive git in the dev loop.)
-- **NO new views, sidebars, activity-bar icons, tree providers, or webviews.** Context menus + palette commands only. Browsing many files is a QuickPick, not a panel.
+- **Keep UI minimal.** Prefer context menus, palette commands, and other built-in surfaces. Add new views, sidebars, tree providers, or webviews only when the UI is integral to the flow and no built-in surface fits — and when you do, build it properly.
 - **NO THROWING EXCEPTIONS for control flow.** Return `Result<T,E>` via a discriminated union. Panics are bugs.
 - **NO REGEX on structured data.** Git porcelain output is parsed via NUL-delimited splits (`-z` flag everywhere). Never regex over JSON, YAML, source code, or git output.
 - **NO PLACEHOLDERS.** If something isn't implemented, leave a loud compilation error with TODO. Silent no-ops = ⛔️ ILLEGAL.

coverage-thresholds.json

@@ -1,5 +1,5 @@
 {
   "_agent_pmo": "74cf183",
   "_doc": "Single source of truth for code coverage thresholds. See REPO-STANDARDS-SPEC [COVERAGE-THRESHOLDS-JSON]. NO GitHub repo variables. NO env vars. NO public `make coverage-check` target. This file is read by the internal `_coverage_check` recipe inside `make test`. `make test` exits non-zero if measured coverage < threshold. Thresholds are monotonically increasing — only ratchet UP, never down.",
-  "default_threshold": 95
+  "default_threshold": 95.3
 }

src/commands/compareWith.ts

@@ -1,14 +1,17 @@
 import * as vscode from "vscode";
 import { TITLE_PREFIX } from "../constants";
 import type { MementoStore } from "../state";
-import { extractHistoryItemSha } from "./historyItem";
+import { historyItemShaFromArgs } from "./historyItem";
 import { type CommandDeps, buildRepo, pickRepoFrom } from "./shared";
 import { drillIntoFiles, pickSideBAndResolve, sideAFromSha } from "./flow";
 
 const NOT_FROM_HISTORY = `${TITLE_PREFIX} this command must be invoked from the SCM history view.`;
 
-const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg: unknown): Promise<void> => {
-  const sha = extractHistoryItemSha(arg);
+const handler = async (
+  deps: CommandDeps & { readonly state: MementoStore },
+  args: readonly unknown[]
+): Promise<void> => {
+  const sha = historyItemShaFromArgs(args);
   if (sha === undefined) {
     void vscode.window.showWarningMessage(NOT_FROM_HISTORY);
     return;
@@ -34,6 +37,6 @@ const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg
 
 export const makeCompareWith =
   (deps: CommandDeps & { readonly state: MementoStore }) =>
-  async (arg: unknown): Promise<void> => {
-    await handler(deps, arg);
+  async (...args: unknown[]): Promise<void> => {
+    await handler(deps, args);
   };

src/commands/compareWithPrevious.ts

@@ -1,15 +1,18 @@
 import * as vscode from "vscode";
 import { REV_KINDS, TITLE_PREFIX } from "../constants";
 import type { MementoStore } from "../state";
-import { extractHistoryItemSha } from "./historyItem";
+import { historyItemShaFromArgs } from "./historyItem";
 import { type CommandDeps, buildRepo, pickRepoFrom } from "./shared";
 import { drillIntoFiles, reportGitError, sideAFromSha } from "./flow";
 
 const REV_PARSE_PARENT_OP = "rev-parse parent";
 const HISTORY_VIEW_WARNING = `${TITLE_PREFIX} this command must be invoked from the SCM history view.`;
 
-const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg: unknown): Promise<void> => {
-  const sha = extractHistoryItemSha(arg);
+const handler = async (
+  deps: CommandDeps & { readonly state: MementoStore },
+  args: readonly unknown[]
+): Promise<void> => {
+  const sha = historyItemShaFromArgs(args);
   if (sha === undefined) {
     void vscode.window.showWarningMessage(HISTORY_VIEW_WARNING);
     return;
@@ -40,6 +43,6 @@ const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg
 
 export const makeCompareWithPrevious =
   (deps: CommandDeps & { readonly state: MementoStore }) =>
-  async (arg: unknown): Promise<void> => {
-    await handler(deps, arg);
+  async (...args: unknown[]): Promise<void> => {
+    await handler(deps, args);
   };

src/commands/compareWithRef.ts

@@ -2,22 +2,22 @@ import * as vscode from "vscode";
 import { REV_KINDS, TITLE_PREFIX } from "../constants";
 import type { RefType } from "../git/types";
 import type { MementoStore } from "../state";
-import { extractHistoryItemSha } from "./historyItem";
+import { historyItemShaFromArgs } from "./historyItem";
 import { type CommandDeps, buildRepo, pickRepoFrom } from "./shared";
 import { drillIntoFiles, pickRefAsSha, sideAFromSha } from "./flow";
 
 const NOT_FROM_HISTORY = `${TITLE_PREFIX} this command must be invoked from the SCM history view.`;
 
 const handler = async ({
   deps,
-  arg,
+  args,
   filter,
 }: {
   deps: CommandDeps & { readonly state: MementoStore };
-  arg: unknown;
+  args: readonly unknown[];
   filter: RefType;
 }): Promise<void> => {
-  const sha = extractHistoryItemSha(arg);
+  const sha = historyItemShaFromArgs(args);
   if (sha === undefined) {
     void vscode.window.showWarningMessage(NOT_FROM_HISTORY);
     return;
@@ -43,6 +43,6 @@ const handler = async ({
 
 export const makeCompareWithRef =
   ({ deps, filter }: { deps: CommandDeps & { readonly state: MementoStore }; filter: RefType }) =>
-  async (arg: unknown): Promise<void> => {
-    await handler({ deps, arg, filter });
+  async (...args: unknown[]): Promise<void> => {
+    await handler({ deps, args, filter });
   };

src/commands/compareWithWorkingCopy.ts

@@ -1,14 +1,17 @@
 import * as vscode from "vscode";
 import { REV_KINDS, TITLE_PREFIX } from "../constants";
 import type { MementoStore } from "../state";
-import { extractHistoryItemSha } from "./historyItem";
+import { historyItemShaFromArgs } from "./historyItem";
 import { type CommandDeps, buildRepo, pickRepoFrom } from "./shared";
 import { drillIntoFiles, sideAFromSha } from "./flow";
 
 const NOT_FROM_HISTORY = `${TITLE_PREFIX} this command must be invoked from the SCM history view.`;
 
-const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg: unknown): Promise<void> => {
-  const sha = extractHistoryItemSha(arg);
+const handler = async (
+  deps: CommandDeps & { readonly state: MementoStore },
+  args: readonly unknown[]
+): Promise<void> => {
+  const sha = historyItemShaFromArgs(args);
   if (sha === undefined) {
     void vscode.window.showWarningMessage(NOT_FROM_HISTORY);
     return;
@@ -30,6 +33,6 @@ const handler = async (deps: CommandDeps & { readonly state: MementoStore }, arg
 
 export const makeCompareWithWorkingCopy =
   (deps: CommandDeps & { readonly state: MementoStore }) =>
-  async (arg: unknown): Promise<void> => {
-    await handler(deps, arg);
+  async (...args: unknown[]): Promise<void> => {
+    await handler(deps, args);
   };

src/commands/flow.ts

@@ -18,16 +18,14 @@ import { CANCELLED, type Cancelled } from "../ui/cancelled";
 import { pickCommit } from "../ui/CommitPicker";
 import { pickRef } from "../ui/RefPicker";
 import { pickSideBChoice, type SideBChoice } from "../ui/SideBPicker";
-import { mergeChangedFilesWithStats, pickFiles } from "../ui/FilePicker";
 import type { MementoStore } from "../state";
-import { buildRepo, openDiff, pickRepoFrom } from "./shared";
+import { buildRepo, openMultiFileDiff, pickRepoFrom } from "./shared";
 
 const GIT_OPS = {
   listRefs: "list refs",
   revParse: "rev-parse",
   log: "log",
   diffNameStatus: "diff --name-status",
-  diffNumstat: "diff --numstat",
   currentBranch: "current branch",
 } as const;
 
@@ -182,45 +180,17 @@ export const drillIntoFiles = async ({
   state: MementoStore;
   output: vscode.OutputChannel;
 }): Promise<void> => {
-  const entries = await collectChangedFiles({ repo, revA, revB, output });
-  if (entries === undefined) {
+  const ns = await repo.nameStatus({ from: revA, to: revB });
+  if (!ns.ok) {
+    reportGitError({ output, op: GIT_OPS.diffNameStatus, e: ns.error });
     return;
   }
-  if (entries.length === 0) {
+  if (ns.value.length === 0) {
     void vscode.window.showInformationMessage(UI_TEXT.noChanges);
     return;
   }
   await state.setLastComparison({ revA, revB, repoRoot });
-  await pickFiles({
-    entries,
-    onPick: async (entry) => {
-      await openDiff({ revA, revB, repoRoot, relPath: entry.file.path });
-    },
-  });
-};
-
-const collectChangedFiles = async ({
-  repo,
-  revA,
-  revB,
-  output,
-}: {
-  repo: GitRepo;
-  revA: CommitRev;
-  revB: RevSpec;
-  output: vscode.OutputChannel;
-}) => {
-  const ns = await repo.nameStatus({ from: revA, to: revB });
-  if (!ns.ok) {
-    reportGitError({ output, op: GIT_OPS.diffNameStatus, e: ns.error });
-    return undefined;
-  }
-  const num = await repo.numstat({ from: revA, to: revB });
-  if (!num.ok) {
-    reportGitError({ output, op: GIT_OPS.diffNumstat, e: num.error });
-    return undefined;
-  }
-  return mergeChangedFilesWithStats(ns.value, num.value);
+  await openMultiFileDiff({ revA, revB, repoRoot, relPaths: ns.value.map((f) => f.path) });
 };
 
 export const sideAFromSha = (sha: Sha): CommitRev => ({

src/commands/historyItem.ts

@@ -27,3 +27,40 @@ export const extractHistoryItemSha = (arg: unknown): string | undefined => {
   }
   return stringIdOf(inner);
 };
+
+// A real SCM history item carries a `parentIds` array alongside its SHA `id`.
+// The git SourceControl provider also has an `id` ("git") but NO `parentIds`,
+// so `parentIds` is what tells the commit apart from the provider VSCode passes.
+const historyItemShaOf = (v: unknown): string | undefined => {
+  if (typeof v !== "object" || v === null) {
+    return undefined;
+  }
+  if ("parentIds" in v && Array.isArray(v.parentIds)) {
+    return stringIdOf(v);
+  }
+  if ("historyItem" in v) {
+    return historyItemShaOf(v.historyItem);
+  }
+  return undefined;
+};
+
+// VSCode invokes `scm/historyItem/context` commands with MULTIPLE arguments —
+// the SourceControl provider (id "git") FIRST, then the history item. Scan for
+// the real history item before anything else so the provider's "git" id is never
+// fed to git as a revision; fall back to the single-argument shapes used by the
+// command palette and older callers.
+export const historyItemShaFromArgs = (args: readonly unknown[]): string | undefined => {
+  for (const a of args) {
+    const sha = historyItemShaOf(a);
+    if (sha !== undefined) {
+      return sha;
+    }
+  }
+  for (const a of args) {
+    const sha = extractHistoryItemSha(a);
+    if (sha !== undefined) {
+      return sha;
+    }
+  }
+  return undefined;
+};

src/commands/shared.ts

@@ -29,6 +29,9 @@ const labelForRev = (rev: RevSpec): string => {
   return UI_TEXT.indexLabel;
 };
 
+export const formatComparisonTitle = ({ revA, revB }: { revA: CommitRev; revB: RevSpec }): string =>
+  `${labelForRev(revA)} ${UI_TEXT.pathArrow} ${labelForRev(revB)}`;
+
 export const formatDiffTitle = ({
   revA,
   revB,
@@ -37,7 +40,7 @@ export const formatDiffTitle = ({
   revA: CommitRev;
   revB: RevSpec;
   basename: string;
-}): string => `${labelForRev(revA)} ${UI_TEXT.pathArrow} ${labelForRev(revB)} ${UI_TEXT.pathDash} ${basename}`;
+}): string => `${formatComparisonTitle({ revA, revB })} ${UI_TEXT.pathDash} ${basename}`;
 
 export const uriForRev = ({
   rev,
@@ -78,6 +81,34 @@ export const openDiff = async ({
   await vscode.commands.executeCommand(BUILT_IN_COMMANDS.diff, left, right, title);
 };
 
+// One persistent multi-diff editor listing every changed file with its full
+// path and inline diff — click a row to jump to that file's diff. This is
+// VSCode's built-in `vscode.changes` editor, NOT a custom view: it takes a
+// title and a list of `[resource, original, modified]` URI triples. We key each
+// row by the on-disk file URI so the list shows clean workspace-relative paths,
+// while the actual diff sides come from `original` (revA, left) and `modified`
+// (revB, right).
+export const openMultiFileDiff = async ({
+  revA,
+  revB,
+  repoRoot,
+  relPaths,
+}: {
+  revA: CommitRev;
+  revB: RevSpec;
+  repoRoot: string;
+  relPaths: readonly string[];
+}): Promise<void> => {
+  const resourceList = relPaths.map((relPath): [vscode.Uri, vscode.Uri, vscode.Uri] => [
+    vscode.Uri.file(path.join(repoRoot, relPath)),
+    uriForRev({ rev: revA, repoRoot, relPath }),
+    uriForRev({ rev: revB, repoRoot, relPath }),
+  ]);
+  const title = formatComparisonTitle({ revA, revB });
+  logger.info({ shaA: shortSha(revA.sha), revBKind: revB.kind, files: relPaths.length }, LOG_EVENTS.diffOpen);
+  await vscode.commands.executeCommand(BUILT_IN_COMMANDS.changes, title, resourceList);
+};
+
 export const repoForUri = (api: GitApi, uri: vscode.Uri): GitVsRepository | undefined => findRepoForUri(api, uri);
 
 export const pickRepoFrom = async (api: GitApi): Promise<Result<GitVsRepository, Cancelled>> => {

src/constants.ts

@@ -33,6 +33,7 @@ export const COMMAND_IDS = {
 
 export const BUILT_IN_COMMANDS = {
   diff: "vscode.diff",
+  changes: "vscode.changes",
   setContext: "setContext",
 } as const;
 
@@ -56,7 +57,6 @@ export const SHORT_SHA_LEN = 7;
 export const GIT_BINARY = "git";
 
 export const NUL = "\x00";
-export const TAB = "\t";
 export const LF = "\n";
 
 export const GIT_LOG_FORMAT = "%H%x00%h%x00%an%x00%at%x00%s";