feat(render): render Slack table blocks as GFM tables

src/slack/render.ts

@@ -109,11 +109,77 @@ function extractMrkdwnFromBlocks(blocks: unknown): string {
       }
       continue;
     }
+    if (type === "table" && Array.isArray(b.rows)) {
+      const table = renderTableBlock(b.rows);
+      if (table) {
+        out.push(table);
+      }
+      continue;
+    }
   }
 
   return out.join("\n\n");
 }
 
+/**
+ * Render a Slack `table` block (composer-pasted tables; also delivered inside
+ * attachment blocks with a "[no preview available]" fallback) as a GFM table.
+ * Rows are arrays of cells; each cell is a rich_text block or `{type: "raw_text", text}`.
+ */
+function renderTableBlock(rows: unknown[]): string {
+  const rendered: string[][] = [];
+  for (const row of rows) {
+    if (!Array.isArray(row)) {
+      continue;
+    }
+    const cells: string[] = [];
+    for (const cell of row) {
+      cells.push(renderTableCell(cell));
+    }
+    rendered.push(cells);
+  }
+  if (rendered.length === 0) {
+    return "";
+  }
+
+  let width = 0;
+  for (const cells of rendered) {
+    width = Math.max(width, cells.length);
+  }
+
+  const lines: string[] = [];
+  lines.push(formatTableRow(rendered[0]!, width));
+  lines.push(formatTableRow(Array(width).fill("---"), width));
+  for (const cells of rendered.slice(1)) {
+    lines.push(formatTableRow(cells, width));
+  }
+  return lines.join("\n");
+}
+
+function formatTableRow(cells: string[], width: number): string {
+  const padded = [...cells];
+  while (padded.length < width) {
+    padded.push("");
+  }
+  return `| ${padded.join(" | ")} |`;
+}
+
+function renderTableCell(cell: unknown): string {
+  if (!isRecord(cell)) {
+    return "";
+  }
+  const text =
+    getString(cell.type) === "rich_text"
+      ? extractMrkdwnFromRichTextBlock(cell)
+      : getString(cell.text);
+  // Flatten to one line and escape pipes, but keep <url|label> link tokens
+  // intact so slackMrkdwnToMarkdown can still convert them.
+  return text
+    .replace(/\s*\n\s*/g, " ")
+    .replace(/(<[^>]*>)|\|/g, (match, token) => (token ? match : "\\|"))
+    .trim();
+}
+
 function extractMrkdwnFromAttachments(attachments: unknown, state: RenderState): string {
   if (state.depth >= MAX_ATTACHMENT_DEPTH) {
     return "";

test/fixtures/render/attachment-fallback-only.json

@@ -0,0 +1,4 @@
+{
+  "text": "",
+  "attachments": [{ "id": 1, "fallback": "[no preview available]" }]
+}

test/fixtures/render/attachment-fallback-only.txt

@@ -0,0 +1 @@
+[no preview available]

test/fixtures/render/table-cell-edge-cases.json

@@ -0,0 +1,37 @@
+{
+  "blocks": [
+    {
+      "type": "table",
+      "block_id": "tbl-edge",
+      "rows": [
+        [
+          { "type": "raw_text", "text": "Item" },
+          { "type": "raw_text", "text": "Status" },
+          { "type": "raw_text", "text": "Notes" },
+          { "type": "raw_text", "text": "Link" }
+        ],
+        [
+          { "type": "raw_text", "text": "Widget A|B" },
+          { "type": "raw_text", "text": "ok" },
+          { "type": "raw_text", "text": "line one\nline two" },
+          {
+            "type": "rich_text",
+            "block_id": "cell-link",
+            "elements": [
+              {
+                "type": "rich_text_section",
+                "elements": [{ "type": "link", "url": "https://example.com/docs", "text": "Docs" }]
+              }
+            ]
+          }
+        ],
+        "bogus-row",
+        [
+          { "type": "raw_text", "text": "Widget C" },
+          { "type": "raw_text", "text": "pending" },
+          { "type": "raw_text", "text": "Q1 & Q2" }
+        ]
+      ]
+    }
+  ]
+}

test/fixtures/render/table-cell-edge-cases.txt

@@ -0,0 +1,4 @@
+| Item | Status | Notes | Link |
+| --- | --- | --- | --- |
+| Widget A\|B | ok | line one line two | [Docs](https://example.com/docs) |
+| Widget C | pending | Q1 & Q2 |  |

test/fixtures/render/table-empty-rows.json

@@ -0,0 +1,19 @@
+{
+  "blocks": [
+    {
+      "type": "rich_text",
+      "block_id": "prose",
+      "elements": [
+        {
+          "type": "rich_text_section",
+          "elements": [{ "type": "text", "text": "Quarterly roundup" }]
+        }
+      ]
+    },
+    {
+      "type": "table",
+      "block_id": "tbl-empty",
+      "rows": []
+    }
+  ]
+}

test/fixtures/render/table-empty-rows.txt

@@ -0,0 +1 @@
+Quarterly roundup

test/fixtures/render/table-in-attachment.json

@@ -0,0 +1,88 @@
+{
+  "text": "Atlas Signups\n===\n\nMedian = +40% WoW\nDriver = beta invite rollout",
+  "blocks": [
+    {
+      "type": "rich_text",
+      "block_id": "prose",
+      "elements": [
+        {
+          "type": "rich_text_section",
+          "elements": [
+            {
+              "type": "text",
+              "text": "Atlas Signups\n===\n\nMedian = +40% WoW\nDriver = beta invite rollout"
+            }
+          ]
+        }
+      ]
+    }
+  ],
+  "attachments": [
+    {
+      "id": 1,
+      "fallback": "[no preview available]",
+      "blocks": [
+        {
+          "type": "table",
+          "block_id": "tbl1",
+          "rows": [
+            [
+              {
+                "type": "rich_text",
+                "block_id": "h1",
+                "elements": [
+                  {
+                    "type": "rich_text_section",
+                    "elements": [{ "type": "text", "text": "Metric", "style": { "bold": true } }]
+                  }
+                ]
+              },
+              {
+                "type": "rich_text",
+                "block_id": "h2",
+                "elements": [
+                  {
+                    "type": "rich_text_section",
+                    "elements": [{ "type": "text", "text": "Wk 1", "style": { "bold": true } }]
+                  }
+                ]
+              },
+              {
+                "type": "rich_text",
+                "block_id": "h3",
+                "elements": [
+                  {
+                    "type": "rich_text_section",
+                    "elements": [{ "type": "text", "text": "Wk 2", "style": { "bold": true } }]
+                  }
+                ]
+              },
+              {
+                "type": "rich_text",
+                "block_id": "h4",
+                "elements": [
+                  {
+                    "type": "rich_text_section",
+                    "elements": [{ "type": "text", "text": "Wk 3", "style": { "bold": true } }]
+                  }
+                ]
+              }
+            ],
+            [
+              { "type": "raw_text", "text": "Signups" },
+              { "type": "raw_text", "text": "120" },
+              { "type": "raw_text", "text": "240" },
+              { "type": "raw_text", "text": "480" }
+            ],
+            [
+              { "type": "raw_text", "text": "WoW" },
+              { "type": "raw_text", "text": "–" },
+              { "type": "raw_text", "text": "+100%" },
+              { "type": "raw_text", "text": "+100%" }
+            ]
+          ]
+        }
+      ]
+    }
+  ]
+}

test/fixtures/render/table-in-attachment.txt

@@ -0,0 +1,10 @@
+Atlas Signups
+===
+
+Median = +40% WoW
+Driver = beta invite rollout
+
+| *Metric* | *Wk 1* | *Wk 2* | *Wk 3* |
+| --- | --- | --- | --- |
+| Signups | 120 | 240 | 480 |
+| WoW | – | +100% | +100% |

test/render-fixtures.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, test } from "bun:test";
+import { readdirSync, readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { renderSlackMessageContent } from "../src/slack/render.ts";
+
+/**
+ * Fixture-pair harness: every `test/fixtures/render/<name>.json` (a raw message
+ * object as passed to renderSlackMessageContent) must render exactly to the
+ * markdown in the sibling `<name>.txt`. Add a new case by dropping in a pair.
+ * Expected outputs are .txt, not .md, so formatters (oxfmt pre-commit) never
+ * rewrite them — they are exact renderer output, not prose.
+ *
+ * Regenerate expected outputs after an intentional rendering change with:
+ *   UPDATE_RENDER_FIXTURES=1 bun test render-fixtures
+ */
+const FIXTURES_DIR = join(import.meta.dir, "fixtures", "render");
+const UPDATE = process.env.UPDATE_RENDER_FIXTURES === "1";
+
+const fixtureNames = readdirSync(FIXTURES_DIR)
+  .filter((f) => f.endsWith(".json"))
+  .map((f) => f.replace(/\.json$/, ""))
+  .sort();
+
+describe("render fixtures", () => {
+  test("fixture directory is not empty", () => {
+    expect(fixtureNames.length).toBeGreaterThan(0);
+  });
+
+  for (const name of fixtureNames) {
+    test(name, () => {
+      const input = JSON.parse(readFileSync(join(FIXTURES_DIR, `${name}.json`), "utf8"));
+      const rendered = renderSlackMessageContent(input);
+      const expectedPath = join(FIXTURES_DIR, `${name}.txt`);
+      if (UPDATE) {
+        writeFileSync(expectedPath, rendered ? `${rendered}\n` : "");
+        return;
+      }
+      const expected = readFileSync(expectedPath, "utf8").replace(/\n$/, "");
+      expect(rendered).toBe(expected);
+    });
+  }
+});