feat: add issue view with body cleaning and truncation (task 0003)

Add `issue view <n>` as the first detail command, introducing the
content-cleaning and truncation machinery (src/body.ts) that later issue
and PR slices reuse.

- Default output: number, title, state, author, created, body (truncated
  at 500), plus comment_count; --comments expands every comment (bodies
  truncated at 800); --full suppresses all truncation.
- cleanBody runs only when a body exceeds its limit: normalizes Gitea
  issue/PR URLs on the detected host to Issue#N/PR#N, strips image embeds
  and long URLs, and collapses quoted blocks.
- Type guard: a PR number fails with VALIDATION_ERROR and a `pr view <n>`
  hint, detected via the fetched object's pull_request field.
- renderDetail joins the detail entity, optional sub-blocks, and help.

src/commands/issue.ts

@@ -1,19 +1,40 @@
-import type { Issue } from "gitea-js";
+import type { Comment, Issue } from "gitea-js";
+import {
+  BODY_TRUNCATE_LIMIT,
+  COMMENT_TRUNCATE_LIMIT,
+  truncateBody,
+} from "../body.js";
 import { createClient } from "../client.js";
 import { resolveRepoContext, type RepoContext } from "../context.js";
 import type { CliDeps } from "../deps.js";
 import { axiError, classifyHttpError } from "../errors.js";
 import { extractRow, lowercased, pluck, relativeTimeField, type FieldDef } from "../fields.js";
 import { parseFlags } from "../flags.js";
-import { formatCountLine, renderList } from "../render.js";
+import { formatCountLine, renderDetail, renderList, type DetailBlock } from "../render.js";
+import { relativeTime } from "../time.js";
 import { suggestCommand } from "../suggestions.js";
 
 export const ISSUE_HELP = `usage: gitea-axi issue <command> [flags]
 
 commands:
   list    List issues in the current repository
+  view    Show a single issue's details
 
-Run \`gitea-axi issue list --help\` for the flags of a command.
+Run \`gitea-axi issue <command> --help\` for the flags of a command.
+`;
+
+export const ISSUE_VIEW_HELP = `usage: gitea-axi issue view <number> [flags]
+
+Show a single issue. Pull request numbers are rejected — use \`pr view\` instead.
+
+flags:
+  --comments   Render every comment in full (bodies truncated at 800 chars)
+  --full       Suppress all truncation of the issue body and comment bodies
+  --help       Show this help
+
+global flags:
+  -R, --repo <OWNER/NAME>     Override the repository detected from the git origin remote
+  --login <name>              Select a tea login profile by name
 `;
 
 export const ISSUE_LIST_HELP = `usage: gitea-axi issue list [flags]
@@ -146,6 +167,152 @@ async function issueList(deps: CliDeps, args: string[]): Promise<string> {
   });
 }
 
+const ISSUE_VIEW_HELP_SUGGESTION = [
+  "Run `gitea-axi issue view --help` to see available flags",
+];
+
+function parseIssueNumber(positionals: string[], command: string): number {
+  if (positionals.length === 0) {
+    throw axiError(`${command} requires an issue number`, "VALIDATION_ERROR", [
+      `Run \`gitea-axi ${command} <number>\``,
+    ]);
+  }
+  if (positionals.length > 1) {
+    throw axiError(
+      `Unexpected argument: ${positionals[1]}`,
+      "VALIDATION_ERROR",
+      ISSUE_VIEW_HELP_SUGGESTION,
+    );
+  }
+  const raw = positionals[0]!;
+  const number = Number(raw);
+  if (!Number.isInteger(number) || number < 1) {
+    throw axiError(
+      `Invalid issue number: ${raw} (expected a positive integer)`,
+      "VALIDATION_ERROR",
+      ISSUE_VIEW_HELP_SUGGESTION,
+    );
+  }
+  return number;
+}
+
+// The default detail fields reuse the same declarative extraction as the list
+// path; only `body` (truncation) and `comment_count` need bespoke handling.
+const ISSUE_VIEW_FIELDS: FieldDef<Issue>[] = [
+  pluck("number"),
+  pluck("title"),
+  lowercased("state"),
+  pluck("author", "user.login"),
+  relativeTimeField("created", "created_at"),
+];
+
+interface IssueDetailOptions {
+  host: string;
+  full: boolean;
+  withComments: boolean;
+  now: Date;
+}
+
+function buildIssueDetail(issue: Issue, options: IssueDetailOptions): Record<string, unknown> {
+  const row = extractRow(issue, ISSUE_VIEW_FIELDS, { now: options.now });
+  const body = issue.body ?? "";
+  row.body = options.full ? body : truncateBody(body, BODY_TRUNCATE_LIMIT, options.host);
+  if (!options.withComments) {
+    const count = issue.comments ?? 0;
+    row.comment_count = count > 0 ? `${count} — use --comments to see full comments` : 0;
+  }
+  return row;
+}
+
+function buildCommentRows(
+  comments: Comment[],
+  options: { host: string; full: boolean; now: Date },
+): Record<string, unknown>[] {
+  return comments.map((comment) => {
+    const body = comment.body ?? "";
+    return {
+      author: comment.user?.login ?? "",
+      created: relativeTime(comment.created_at, options.now),
+      body: options.full ? body : truncateBody(body, COMMENT_TRUNCATE_LIMIT, options.host),
+    };
+  });
+}
+
+function issueViewSuggestions(
+  context: RepoContext,
+  number: number,
+  options: { withComments: boolean; commentCount: number; bodyAbbreviated: boolean },
+): string[] {
+  const help: string[] = [];
+  if (!options.withComments && options.commentCount > 0) {
+    help.push(suggestCommand(context, `issue view ${number} --comments`, "to see full comments"));
+  }
+  if (options.bodyAbbreviated) {
+    help.push(suggestCommand(context, `issue view ${number} --full`, "to see the complete body"));
+  }
+  if (help.length === 0) {
+    help.push(suggestCommand(context, `issue view ${number} --help`, "to see all issue view flags"));
+  }
+  return help;
+}
+
+async function issueView(deps: CliDeps, args: string[]): Promise<string> {
+  if (args.includes("--help")) {
+    return ISSUE_VIEW_HELP;
+  }
+  const { flags, positionals } = parseFlags(
+    args,
+    { "--comments": { takesValue: false }, "--full": { takesValue: false } },
+    "issue view",
+  );
+  const number = parseIssueNumber(positionals, "issue view");
+  const full = flags["--full"] === true;
+  const withComments = flags["--comments"] === true;
+
+  const context = await resolveRepoContext(deps);
+  const api = createClient(context);
+  let issue: Issue;
+  try {
+    const response = await api.repos.issueGetIssue(context.owner, context.name, number);
+    issue = response.data;
+  } catch (error) {
+    throw classifyHttpError(error);
+  }
+
+  if (issue.pull_request) {
+    throw axiError(`issue #${number} is a pull request`, "VALIDATION_ERROR", [
+      suggestCommand(context, `pr view ${number}`, "to view this pull request"),
+    ]);
+  }
+
+  const now = new Date();
+  const item = buildIssueDetail(issue, { host: context.host, full, withComments, now });
+
+  const blocks: DetailBlock[] = [];
+  if (withComments) {
+    let comments: Comment[];
+    try {
+      const response = await api.repos.issueGetComments(context.owner, context.name, number);
+      comments = response.data ?? [];
+    } catch (error) {
+      throw classifyHttpError(error);
+    }
+    blocks.push({ noun: "comments", rows: buildCommentRows(comments, { host: context.host, full, now }) });
+  }
+
+  const commentCount = issue.comments ?? 0;
+  // Suggest --full whenever the rendered body differs from the raw one — cleaned
+  // or truncated alike — read straight off the rendered output so the two never
+  // drift from truncateBody's own limit decision.
+  const bodyAbbreviated = item.body !== (issue.body ?? "");
+  return renderDetail({
+    noun: "issue",
+    item,
+    blocks,
+    help: issueViewSuggestions(context, number, { withComments, commentCount, bodyAbbreviated }),
+  });
+}
+
 export function issueCommand(deps: CliDeps) {
   return async (args: string[]): Promise<string> => {
     const [subcommand, ...rest] = args;
@@ -155,6 +322,9 @@ export function issueCommand(deps: CliDeps) {
     if (subcommand === "list") {
       return issueList(deps, rest);
     }
+    if (subcommand === "view") {
+      return issueView(deps, rest);
+    }
     throw axiError(`Unknown issue command: ${subcommand}`, "VALIDATION_ERROR", [
       "Run `gitea-axi issue --help` to see available issue commands",
     ]);